NAT'L INST. OF STAND & TECH

AlllDti MTS17E

NIST

PUBUCATIONS BEFEBEMCE

Nisr

National Institute of Standards and Technology

Technology Administration, U.S. Department of Commerce

NIST Technical Note 1541

Signals Before, During, and After the

Implosion of a Large Sports Stadium

(Veterans' Stadium in Philadelphia)

Christopher L. Holloway

Galen Koepke

Dennis Camell

Kate A. Remley

Dylan F. Williams

Susan A. Schima

Seturnino Canales

S-OOS

NIST Technical Note 1541

Propagation and Detection of Radio Signals

Before, During and After the Implosion of a Large

Sports Stadium (Veterans' Stadium in

Philadelphia)

Christopher L. Holloway

Galen Koepke

Dennis Camell

Kate A. Remley

Dylan F. Williams

Susan A. Schima

Seturnino Canales

Electromagnetics Division

National Institute of Standards and Technology

325 Broadway

Boulder, CO 80305

October 2005

.<°>^.

U.S. Department of Commerce

Carlos M. Gutierrez, Secretary

Technology Administration

Michelle O'Neill, Acting Under Secretary of Commerce for Technology

National Institute of Standards and Technology

William Jeffrey, Director
Certain commercial entities, equipment, or materials may be

identified in this document in order to describe an experimental

procedure or concept adequately. Such identification is not intended to imply recommendation or endorsement by the

National Institute of Standards and Technology, nor is it intended to imply that the entities, materials, or equipment

are necessarily the best available for the purpose.

National Institute of Standards and Technology Technical Note 1541

Natl. Inst. Stand. Technol. Tech. Note 1541, 122 pages (October 2005)

CODEN: NTNOEF

U.S. Government Printing Office

Washington: 2005

For sale by the Superintendent of Documents, U.S. Government Printing Office

Internet bookstore: gpo.gov Phone:202-512-1800 Fax:202-512-2250

Mail: Stop SSOP, Washington, DC 20402-0001
Contents

Executive Summary iv

Abstract 1

1. Introduction 1

2. Stadium Description 3

3. Frequency Bands 3

4. Transmitters 5

5. Receiving Antenna and Measurement System 6

6. Experimental Set-up 8

7. Experimental Results 10

7.1 Radio Mapping of Stadium: Measuring Signal Strengths 10

7.1.1 External Stadium Measurements 10

7.1.2 Internal Stadium Measurements 11

7.2 Radio Mapping of Stadium: Statistical Distributions of

Signal Strength 11

7.3 Pre-implosion Radio Signal Measurements with Transmitters

at Fixed Sites 13

7.3.1 Signal Strength Measurements for Fixed Sites 14

7.3.2 Statistical Distributions of Signal Strength for Fixed Sites 15

7.4 Implosion Radio Signal Measurements with Transmitters at Fixed Sites with Fixed and Mobile Receiving Sites 18

7.5 Field Tests of the Debris Radiator Concept 20

8. Recovery of Transmitters 23

9. Summary of Results and Conclusion 23

10. References 27

111
Executive Summary

This is the second in a series of NIST technical notes (TN) on propagation and detection of radio

signals in large buildings before, during, and after implosion. The first NIST TN (NIST TN

1540) described a similar experiment carried out on a 13-story apartment building in New

Orleans, LA. These data will give first responders a better understanding of what to expect from

the radio-propagation environment in disaster situations. The goals of this work are two-fold: (1) to create a large, public-domain data set describing the attenuation in various building types of

radio signals in public safety and cellular telephone bands and (2) to investigate various schemes

for detecting signals from first responders with radios or from civilians with cell phones who are trapped in voids in a collapsed or partially collapsed building.

With the above goals in mind, measurements were carried out on a large sports stadium (the

Veteran's Stadium) in Philadelphia, PA. Frequencies near public safety and cell phone bands

(approximately 50 MHz, 150 MHz, 225 MHz, 450 MHz, 900 MHz, and 1.8 GHz) were chosen

for these experiments. Radio transmitters similar to those used by first responders were used. An

automated system to measure signal strength was developed. Three different types of signalstrength experiments were performed.

First, we carried out a "radio-mapping" experiment that provided data on how well radio signals

at the different frequencies coupled into the stadium. From this we determined the field strength

variability throughout the stadium. This experiment involved carrying a set of transmitters tuned

to the various frequencies throughout the stadium, while recording the received signal at a fixed

receive site located outside the building. Transmitters were also carried around the perimeter of

the stadium with a fixed receiving site on the outside. These measurements were carried out a few days before the stadium was imploded. Results show that:

Maximum signal attenuation for the perimeter mapping of the stadium was on the order

of75dB.

The mean interior to exterior signal attenuation ranged from 25 to 50 dB.

The standard deviation for interior to exterior signal attenuation ranged from 6 to 14 dB, depending on frequency.

These results indicate the variability in signal level that a communication-system user might

expect throughout a structure of this type.

Second, radios in protective cases were placed in fixed sites throughout the stadium. Received

signals were collected external to the structure before, during, and after the implosion. Our

receiving sites in this case were both fixed and mobile. A mobile cart was pulled around the

perimeter of the stadium both before and after the implosion, enabling direct comparison of

signal strength as a function of azimuth angle through the standing stadium and the resulting pile

of rubble. Results show that:

Some transmitter signals experienced large amounts of attenuation (some greater than

100 dB, at the noise floor of our receivers), while other transmitter signals increased

during the implosion, depending on the receiving site and location of the transmitter

cache.

IV
Large amounts of building rubble caused at least 30 to 50 dB of signal attenuation. The

true attenuation was not established in several cases since we measured only noise.

Thus, if someone was trapped under such a rubble pile and tried to communicate with an emergency responder with a two-way radio or cell phone, their communication link would have

to overcome at least 30 to 50 dB of attenuation. It is interesting to note that the increase in signal

attenuation after the collapse of the stadium was not as large as we expected based on results

observed during the apartment building implosion (60 to 80 dB). We attribute this to massive

amounts of concrete and steel in the standing stadium that heavily attenuated signals propagating

through the interior of the stadium. While the implosion certainly moved and compacted these

massive beams, there were still large voids remaining in the rubble pile, leaving us with a propagation environment similar to that of the stadium's standing state. The apartment building,

however, went from a relatively open structure to a very dense pile of rubble that had a more

pronounced effect on the signals.

The third set of experiments used metallic "debris radiators" to attempt to detect signals from

transmitters buried underneath the rubble pile. The goal was to investigate whether radio signals

from transmitter(s) under rubble might couple onto metallic construction material such as pipes

or conduit, and radiate signals to the edges of the rubble pile. Results show that:

Signals could be received from all buried transmitters using either a direct connection to the metallic debris through a matching network or a directional receive antenna placed

in close proximity to the debris radiator.

Directional receive antennas in close proximity to a debris radiator generally had higher

received signal levels than did signals acquired using direct connection to the metallic

debris.

The results given in this NIST TN are the second in a series of reports detailing implosion

experiments performed by NIST in order to better understand the first responder' s radio

propagation environment and to investigate new methods for weak-signal detection. The first set of implosion experiments was performed in an apartment building in New Orleans. The results

of that experiment and implosion experiments performed in the Washington D.C. Convention

Center are the subject of separate NIST TNs. Besides implosion experiments, NIST has also

performed radio-mapping experiments in various other large structures, including apartment and

office buildings, sports stadiums, stores, malls, hotels, a convention center, and warehouses. The

results of the signal-strength measurements and statistical distribution for these radio-mapping

experiments will also be published separately.

Propagation and Detection of Radio Signals Before, During and After the

Implosion of a Large Sports Stadium (Veterans' Stadium in Philadelphia)

Christopher L. Holloway, Galen Koepke, Dennis Camell,

Kate A. Remley, Dylan F. Williams, Susan A. Schima, and Setumino Canales

Electromagnetics Division

National Institute of Standards and Technology

325 Broadway, Boulder, CO 80305

In this report, we investigate radio communications problems faced by emergency responders

(firefighters and police) in disaster situation such as collapsed buildings. A fundamental

challenge to communications into and out of large buildings is the strong attenuation of radio

signals caused by losses and scattering in the building materials and structure. We designed

experiments that take advantage of building demolitions in an effort to quantify radio-signal

attenuation through standing and collapsed structures. We also investigated various schemes

for detecting signals from firefighters and civilians with portable radios or cell phones who are trapped in voids in these collapsed building. We placed RF transmitters, similar to those used by

first responders, in various locations in these buildings and performed measurements before,

during, and after the building was imploded. The transmitters were tuned to frequencies near

public safety and cell phone bands. Once the building was down, we measured the signals from

the buried transmitters in the building to investigate weak-signal detection schemes that involved

searching with directional antennas and connecting instruments to some of the metal debris

located on the perimeter ofthe collapsed building. This report summarizes the second in a series

of such experiments, performed in Veterans' Stadium in Philadelphia, PA. In this report, we

describe the experiments, detail the measurement system, show primary results of the data we

collected, and discuss some ofthe interesting propagation effects we observed.

Key words: building implosion; building shielding and coupling; collapsed buildings; emergency

responders; radio communications; radio propagation experiments; weak-signal detection

1. Introduction

When emergency (or first) responders enter large structures (e.g., apartment and office buildings,

sports stadiums, stores, malls, hotels, convention centers, and warehouses) communication to individuals on the outside is often impaired. Cell phone and mobile-radio signal strength is reduced due to attenuation caused by propagation through the building materials and scattering

by the building geometry [1-5].

We report on a National Institute of Standards and Technology (NIST) project to investigate the

communications problems faced by first responders (firefighters and police) in disaster situations

such as collapsed buildings. As part of this effort, we are investigating the propagation and

coupling of radio-waves into large structures. We are also investigating various schemes for
detecting first responders and civilians with portable radios or cell phones who are trapped in

voids of a collapsed or partially collapsed building.

Buildings scheduled for implosion provide the ideal research environment for investigating

radio-wave propagation conditions in fully or partially collapsed structures. The rapid change in

the building structure during an implosion was also favorable to our experimental time frame.

We could perform one set of experiments within about a two-week period as opposed to several

months during a conventional demolition. Working in cooperation with demolition and

implosion contractors, we identified a high-rise apartment building in New Orleans as the site of

our first set of experiments. A summary of this work appears in References [5] and [6]. This

current report summarizes the second in a series of implosion experiments. The data discussed

here were collected during the implosion of the Veteran Stadium in Philadelphia, PA, in March

2004.

The experiments reported here were performed before, during, and after the implosion of the

building and are essentially measurements of the reduction in radio signal strength caused by

propagation through the structure. In order to study the radio characteristics of the building at the various frequencies of interest to first responders, frequencies near public safety and cell phone bands (approximately 50 MHz, 150 MHz, 225 MHz, 450 MHz, 900 MHz, and 1.8 GHz)

were chosen. A detailed description of the transmitters we used is given in Section 4.

Three types of data were collected in the experiment. The first set of data, which we refer to as a "radio mapping," was collected a few days before the building was imploded. This involved

carrying transmitters (or radios) tuned to various frequencies throughout the stadium while

recording the received signal at a site located outside the stadium. The reference for these data

was a direct, unobstructed line-of-sight signal-strength measurement with the transmitters

external to the stadium and in front of the receiving antennas. The purpose of the radio-mapping

measurements was to investigate how the signals at the different frequencies couple into the

stadium, and to determine the field strength variability throughout the stadium.

The second set of data was gathered from radios placed at fixed sites throughout the stadium.

Received signals were collected before, during, and after the implosion. The receiving systems in

this case were both at fixed sites and mobile. The mobile receiving system consisted of

measurement instruments and antennas mounted on a modified garden cart. A detailed

description of the measurement system and antennas is given in Section 5. The cart was pulled

around the perimeter of the stadium both before and after the implosion, enabling direct

comparison of signal strength as a function of (a) azimuth angle through the standing stadium

and (b) the resulting pile of rubble after the collapse.

The third set of data consisted of monitoring signals coupled to metallic debris located in the

proximity of transmitters buried in the collapsed stadium. These metallic "debris radiators" (a set of cables laid to investigate the concept) ran through the rubble and were exposed at the

perimeter of the collapsed stadium. The idea is that when a large structure collapses, metal

objects (electrical wires, metal piping, re-bar, venting pipe, etc.) protrude from the rubble. These

objects may improve radio reception by coupling radio signals to searchers on the outside. When

first responders approach a collapsed structure, one of their first priorities is to determine
whether survivors are present in the debris. Reception of signals from handheld radios or cell phones may let searchers know of survivors' presence and their condition. We measured the

signals from the buried transmitters using instruments physically connected to the metallic debris

through impedance tuners. Antennas were also used to investigate signal detection from these

metallic debris radiators.

This report summarizes a set of experiments in a large sports stadium in Philadelphia, PA,

formally known as Veterans' Stadium (see Figure 1). Details of the stadium layout are presented

in Section 2. Section 3 describes the frequencies used in these experiments. Section 4 discusses

the transmitters and Section 5 describes the automated measurement system used in the radiomapping and propagation measurements. In Section 6, our experimental procedures are discussed. In Section 7 we present the data collected at various stages of the experiment. Section

8 briefly discusses the recovery of the transmitters after the implosion. Finally, in Section 9, we

summarize the results of these experiments and discuss some of the interesting propagation

effects observed.

2. Stadium Description

The structure for the radio propagation experiments discussed in this report was Veterans'

Stadium, a large sports arena in Philadelphia, PA (see Figure 1). The nearly circular stadium

was constructed of reinforced concrete, steel, and standard interior finish materials. Figures 1-3

show details of the original stadium and some of the preparations and partial demolition of the

different sections of the stadium. As shown in these figures, the stadium had multiple levels with

large open areas. The exterior perimeter of the stadium was approximately 805 m (1/2 mile).

Significant demolition was already completed when we arrived two weeks before the implosion;

all plumbing fixtures, most glass windows and doors, and other contents had been removed.

Material had been judiciously removed from certain structural parts of the lower levels including

stairwells and elevator shafts to facilitate a proper collapse during the implosion. Figure 4 shows

a plan of the structure and approximate locations of the transmitter and receive instruments.

3. Frequency Bands

An overview of the frequencies used by the public safety community nationwide (federal, state, and local) is given in Table 1 . From this table, we see that there is a broad range of frequencies

ranging from 30 MHz to 4.9 GHz. The modulation scheme has historically been analog FM, but

this is slowly changing to digital as Project 25 radios come online [7]. The modulation

bandwidth in the VHF and UHF bands has been 25 kHz, but due to the need for additional

communications channels in already crowded spectrum, all new bandwidth allocations are 12.5

kHz. The older wide-bandwidth allocations will gradually be required to move to narrow

bandwidths to increase the user density even further. The crowded spectrum and limited

bandwidth are also pushing the move to higher frequency bands in order to use new dataintensive technologies. The cellular phone bands are summarized in Table 2.
As shown in Table 1, frequencies currently used by public safety and other emergency

responders and cellular telephones are typically below 2 GHz, for current technology. New

frequency allocations and systems including higher frequencies (e.g., around 4.9 GHz) will

become increasingly important in the future, but in these studies, we concentrated on the major

communications bands in use today. We chose six frequency bands below 2 GHz, from about

50 MHz to just above 1 800 MHz. These include four VHF bands typically used for analog FM

voice, one band used for multiple technologies (analog FM voice, digital trunked FM, and

cellular telephone), and one band near the digital cellular telephone band.

Table 1. Public safety community frequencies.

Frequency band Description

30-50 MHz Used mainly by highway patrol for long-distance propagation. This

is currently being phased out of use. 150-174 MHz Local police and fire. Lower frequency again used because of its better long distance propagation quality.

406-470 MHz Used by federal officers and others.

700-800 MHz Used in urban areas. 800-869 MHz Primarily urban usage.

4.9 GHz A newly allocated band with 50 MHz bandwidth just coming on

line for sending images and data.

Table 2. Cellular phone frequencies.

Frequency band

(MHz)

Description

800 AMPS or analog systems

1900 PCS or digital system

In designing an experiment to investigate the propagation characteristics into large buildings at these different frequency bands, we chose frequencies very close, but not identical, to the above

bands. If frequencies were chosen in the public safety or commercial land-mobile bands,

interference to the public safety and cellular systems could possibly occur. Conversely, these

existing systems could interfere with our experimental setup. In addition, obtaining frequency

authorizations in these bands for our experiments would have been problematic due to the

intense crowding of the spectrum. To circumvent these issues we were able to receive temporary

authorization to use frequencies in the U.S. government frequency bands adjacent to these public

safety bands. Table 3 lists the frequency bands that were used in the experiments. The lower

four bands correspond to the frequencies used by the public-safety community; 902 MHz can be

associated with several services including public safety and cellular phone; and the highest

frequency is near the digital cellular phone band.
Table 3. Frequency bands used in the experiments.

Frequency band

(MHz)

Description

49 Simulate a public safety band

162 Simulate a public safety band

226 Simulate a public safety band

448 Simulate a public safety band

902 Simulate a public safety or cellular phone band

1830 Simulate a cellular phone band

Table 4. Frequency sets and grouping used in the experiments

Band

(MHz)

Location A

(MHz)

Location B

(MHz)

Location C

(MHz)

Location D

(MHz)

49 49.78 49.66 49.72 49.60

162 162.20 163.3 165.54 162.90

226 226.50 225.4 226.4 225.30

448 448.80 448.60 448.70 448.50

902 902.45 902.60 — ~

1830 1830.0 1831.00 ~ ~

For the fixed transmitter experiments, where signals were monitored before during and after the

implosion, twenty transmitters operating at different frequencies within the above six bands were

placed at four different locations in the stadium (refer to Fig. 4). The 20 different frequencies

used in this experiment are listed in Table 4. The first two locations had frequencies in all six

bands, while the last two locations had transmitters tuned to only four different frequency bands.

A detailed description of the transmitters is given in the next section.

4. Transmitters

The design requirements for the transmitters used in this experiment were to (1) transmit at the

frequencies listed in the tables above, (2) operate continuously for 12 h, (3) be sufficiently

robust to have a high probability of surviving the building collapse, and (4) be relatively

inexpensive in the event that they did not survive the building collapse.

To accomplish this, two different types of transmitters were chosen. For the four lower frequency

bands (the VHF/UHF public-safety bands), off-the-shelf amateur radios were modified. The

modifications included (a) reprogramming the frequency synthesizer to permit transmitting at government frequencies, (b) disabling the transmitter time-out-timer mode in order to allow for a continuous transmission, and (c) connecting a large external battery pack. The specifications of
these modified radios then had to be reported to the National Telecommunications and

Information Administration (NTIA) frequency coordinator in order to gain approval for use in

government frequency bands. With the larger battery packs, the modified radios could transmit

continuously for 12 to 18 h. The extended transmitting time required us to provide additional

cooling since the radios were designed for typical communications, that is, to transmit

intermittently with cooling time between transmissions.

The stability and radiated power from these inexpensive radios was measured over a 24-hour

period. This measurement was performed in the NIST reverberation chamber, and is discussed

below. The modified radios and battery packs were placed in durable orange plastic cases to provide some protection from debris during the implosion. These cases obviously could not

withstand a crushing load of debris, so careful placement in the building was key to survival.

Figure 5 shows the final arrangement of modified transmitters used for the lower four frequency

bands.

Commercial transmitters were available for the two higher frequency bands (900 and

1800 MHz). These off-the-shelf transmitters were already in plastic protective cases and could

transmit continuously for 12 h. Figure 6 shows these transmitters. Note that the higherfrequency transmitters were grey in color and not orange.

To ensure that the plastic protective cases did not affect the total radiated power and radiation

pattern of the transmitters, measurements of these two quantities were taken in the NIST

reverberation and fully anechoic chambers. Measurements of the total radiated power both with

and without the plastic cases indicated that the cases had minimal effect on the total radiated

power. Radiated power patterns of the transmitters in the protective cases were also measured to ensure that the cases did not have dramatic effects on the radiation patterns. The transmitters were placed in the NIST anechoic chamber (see Figure 7) for these pattern measurements.

Figures 8-10 illustrate the results for 164 MHz, 225 MHz, and 448 MHz. These figures show

that the radiation patterns of the transmitters in the protective cases were very similar to the

dipole type pattern that the radio would produce in free space.

5. Receiving Antenna and Measurement System

The receiving system is sketched in Figure 1 1 . We assembled four antennas on a 4-meter mast

as illustrated. The radio-frequency output from each antenna was fed through a 4:1 broadband

power combiner. This arrangement gave us a single input to the portable spectrum analyzer,

which could then scan over all the frequencies of interest without switching antennas. The four

antennas were chosen to be optimal (or at least practical) for each of the frequency bands we

were measuring. The selected antennas were an end-fed vertical omnidirectional antenna for

50 MHz, a log-periodic-dipole-array (LPDA) used for the 160, 225, and 450 MHz bands, and

Yagi-Uda arrays for 900 and 1830 MHz. This assembly could then be mounted on a fixed tripod

at one of the listening sites, or it could be inserted into the modified garden cart for portable

measurements. The receiving sites contained, in addition to the antenna system, a generator,

uninterruptible power supply (UPS), spectrum analyzer, global posidoning system (GPS)
receiver, computer, and associated cabling. Photos of the antenna assembly mounted on a tripod

and mounted on the mobile cart are shown in Figure 12.

As shown in Figure 11, the measurement system consists of a portable spectrum analyzer, GPS

receiver, and a laptop computer. The data collection process was automated using a graphical

programming language. This software was designed to control the analyzer, collect, process, and

save data at the maximum throughput of the equipment. The software controlled the spectrum

analyzer via an IEEE-488 interface bus and the GPS receiver via a serial interface. The GPS

information was recorded to track the position of the mobile cart during the perimeter

measurements around the building.

The software was written to maximize throughput of the data collection process and to run for an

undefined time interval. This was achieved by running parallel processes of collecting,

processing, and saving the data for post-collection processing. The data were continuously read

from the spectrum analyzer at its optimal settings and stored in data buffers. These buffers were

read and processed for each signal and displayed for operator viewing. The processed data were

then stored in additional buffers to be re-sorted and saved to a file on disk.

The initial setup of the parameters for the spectrum analyzer detemiined the quality of

optimization for this process. There were several instrument parameters that were critical during

the setup, including the analyzer sweep time, resolution bandwidth and frequency span of the

spectrum analyzer trace. The number and spread of the test frequencies in a particular band

influenced the allowed range of adjustment for these parameters. These two factors also

influenced the number of traces necessary to cover all the test frequencies. Interference from

signals in the adjacent spectrum influenced the instrument setup and data collection speed by

forcing smaller resolution bandwidths. The reference level for each trace was also checked and

adjusted during the measurement to improve the resolution and accuracy of the power level

reading. All of these factors had some effect on the sampling rate.

The sampling rate of a complete measurement sequence was the major factor in how much

spatial resolution we had during walk-through or field-mapping experiments (we also had some

flexibility in our walking speed) and the time resolution for recording the signals during the

implosion. The time resolution of the measured data determined how much detail we could

record for the rapid changes in signal strength as the building collapsed. Even though we were

concerned primarily with the before and after values, we hoped to record the signals with enough

detail to correlate the movement of the structure during the event to our received signals.

We used three different models of spectrum analyzers, each having a different sampling rate,

ranging from about 2 to 7 s, to measure all 20 frequencies in the six frequency bands. The

frequencies were spaced such that we could utilize one spectrum analyzer trace for each band.

These rates were achieved only after optimizing the instrument control and data transfer

processes mentioned above. The data from the spectrum analyzer trace were saved in binary

format to disk (to allow us to reprocess the raw data at a later time if needed); they were then

processed to extract the signals at each particular frequency. These results were then put into a spreadsheet file and saved with other measurement information. The sampling rates were
sufficient for the field-mapping experiments (if we did not walk too fast) but very few samples

could be recorded during the implosion.

6. Experimental Set-up

Three types of data were collected in the experiment. The first set of data, which is here referred

to as a "radio mapping," was collected a few days before the building was imploded. This

involved carrying transmitters (or radios) tuned to various frequencies through the interior and

exterior of the stadium while recording the received signal from a site located outside the

stadium. The purpose of these measurements was to investigate how signals at the different

frequencies couple into the stadium and to determine the variability in field strength throughout

the stadium. Also, by carrying the transmitters around the exterior perimeter of the stadium the

amount of signal blockage caused by the stadium from one side to the other could be

investigated. For the radio mapping experiments, one fixed receiving site (as described above)

was assembled on the southwest perimeter of the stadium (see Figure 13), approximately 53 m

from Column #10. During this experiment, the transmitters were carried (and at times, driven

aboard an all-terrain-vehicle or ATV) throughout the stadium (see Figure 14) and the received

signal levels were recorded. Measurements were performed with the receiving antennas

polarized in both the horizontal and vertical direction (with respect to the ground). As the

received signal was recorded, the location of the transmitters in the buildings was also recorded.

For the second data set, radios were placed at four different fixed locations in the stadium where

they would have a high likelihood of surviving the implosion. These four sites are labeled as "TX A", "TX B", "TX C", and "TX D" in Figure 4. Received signals were collected before,

during, and after the implosion. After a careful analysis of the building, the following four sites were chosen: (1) against a concrete wall on the west side of the stadium in a sublevel (Site TX A:

see Figure 15); (2) on the playing field against a concrete retaining wall (Site TX B, see Figure

16); (3) against a concrete wall on the south side of the stadium in a sublevel (Site TX C, see Figure 17); and (4) in a turnstile on the third level of the stadium (Site TX D, see Figure 18).

A few comments are in order about the transmitters against concrete walls on the west and south

side of the stadium. This building had no basement, however, these two walls were below ground

level and the walls were backed by dirt. These walls were part of a large open area that opened

onto the playing field (see Figures 15 and 17). During the implosion these walls would not

collapse, because the implosion was designed to have the upper levels roll over these walls.

However, these walls would be covered with a significant amount of debris. Placing the

transmitters against these concrete walls ensured that these two sets of transmitters would have

some protection from the impact of the collapse and the majority of the concrete rubble would be on top of the transmitters after the implosion. In a similar manner, the transmitters on the playing

field were first placed against a retaining wall and a large concrete column was then laid on top

of transmitters (see Figure 16). Because the stadium was designed to roll onto the playing field

during the implosion, this concrete column ensured that this set of transmitters would have some

protection from the impact of the collapse and the majority of the concrete rubble would be on

top of the transmitters after the implosion. Finally, the transmitters on the third level were tied to a metal turnstile to provide protection from the impact as the stadium levels collapsed and fell onto the playing field.
To protect all the transmitters from implosion dust, they were all wrapped in blast cloth, a fabric

used to contain shrapnel from the explosions (see Figure 19). Notice that plywood was placed

near the transmitters located at the south and west walls. This was done to give added protection

to the transmitters from flying shrapnel.

The receiving sites in this second mode of data collection were both fixed and mobile. Three

fixed receiving sites were used to collect data before, during, and after the implosion. These three

sites were placed around the perimeter of the stadium (see Figures 4 and 20). Receiving site RX

1 was placed approximate 53 m (173 ft) from the south west perimeter of the stadium. The

measurement equipment at this site was placed in a yellow metal construction container (see

Figure 20a) for protection during the implosion. Receiving site RX 2 was placed 37 m (120 ft) from the south east perimeter of the stadium. The measurement equipment at this site was placed

in a small guard building (see Figure 20b) for protection during the implosion. A piece of

plywood was placed over the front window of this building for additional protection (Figure

20b). This precaution was actually necessary because the plywood took direct hits from flying

concrete. Receiving site RX 3 was placed 53 m (173 ft) from the north west perimeter of the

stadium. The measurement equipment at this site was placed in the NIST van (see Figure 20b)

for protection during the implosion. Since these three sites were very close to the stadium, there were no personnel present in them during the implosion. During the implosion the receiving

antennas at receiving site RX 1 and RX 2 were polarized in the vertical direction, while the three

high-band antennas at receiving site RX 3 were polarized in the horizontal direction. These

different polarizations were chosen in order to investigate whether polarization effects would be

significant during the implosion. The idea was to see if the stadium rubble would have the effect

of depolarizing the transmitter signals.

The mobile receiving system consisted of measurement instruments placed on a cart (see Figure

21) as described above. The cart was pulled around the perimeter of the building both before and

after the implosion, enabling direct comparison of signal strength through the standing building

and later through the rubble.

We collected a third set of data to investigate the use of so-called "debris radiators." This set of

data was collected by first using antennas and then connecting instruments through tunable

impedance matching network to metal in the building rubble. This experiment was designed to investigate the possibility of detecting radio signals from a buried transmitter that might couple

onto metal objects such as electrical wires, metal pipes, re-bar, venting ducts, etc., and carry

signals to the edges of the rubble pile.

To simulate the best-case scenario, the experiment was designed to ensure that there was an unbroken metallic object placed near two of the transmitter sets. Steel cables were used as the

metal object and were placed near the transmitters at sites TX A and TX B (labeled as Cables 1 and 2 in Figure 4). The cables were then run 15 m from the stadium perimeter (see Figures 22

and 23). The 15 m distance was anticipated to be beyond the point where the building debris

would lie after the implosion so that we could connect instruments to the ends of the cable.
7. Experimental Results

In this section the measured data are presented. This section is divided into several subsections,

with each subsection covering the different types of experiments performed in the effort.

7.1 Radio Mapping of Stadium: Measured Signal Strengths

The six different frequencies hsted in Table 5 are the ones used in the radio mapping, or "walkthrough", experiments. The receiving site for this set of experiments was outside the stadium at a location approximately 53 m (173 ft) on the south side straight out from Column #10 (see

Figures 4). To calibrate the system, the transmitting units were turned on at a location outside the

stadium, which was at a line-of-sight (LOS) location between the receiving antennas and the

stadium. After all six transmitters were turned on, the units were carried either around the

perimeter or through the interior of the stadium. At various points both inside and outside the

stadium, the transmitter locations were noted in the data file.

Table 5. Frequencies used in the stadium walk-through experiments.

Frequency band

(MHz)

Description

49.60 Simulates a public safety band

162.09 Simulates a public safety band

225.30 Simulates a public safety band

448.50 Simulates a public safety band

902.45 Simulates a public safety or cellular phone band

1832.00 Simulates a cellular phone band

7.1.1 External Stadium Measurements

Figures 24 and 25 show the received signal strengths as the transmitters were carried around the

perimeter of the stadium. Each figure shows the six frequencies listed in Table 5 and the two

different figures correspond to the vertical or horizontal polarization of the receiving antenna

The results in these figures have been normalized to the peak received signal at their respective

frequencies. The peak values occurred at the line-of-sight reference location. From these graphs

we can see that as the transmitters are carried around the perimeter of the stadium the signal

strength steadily decreases, reaching a minimum of -70 to -75 dB on the backside, then steadily

increases again. Part of this decrease is due to the distance fall-off proportional to Mr, which for

the diameter of the stadium (-256 m) could be on the order of 20 dB. The data are not corrected

for this 1/r effect since we are interested in the net effect of the structure and its physical size on

communications. The net effect indicates that, since the stadium is such a large structure,

communication problems can occur when simply trying to communicate external to external

(i.e., from one side of the stadium to the other). This was also observed in our personal

communication equipment used during this test. Personnel at the receiving site were in

10
communication with the personnel carrying the transmitters via two-way 160 MHz radios. This

communication link allowed us to mark the location of the transmitter recorded on the dataset at the receiving site. When the transmitters were located on the back side of the stadium,

communication using our two-way radios was very difficult.

7.1.2 Internal Stadium Measurements

Figures 26-28 show the received signal strengths for the data collected during the building walkthroughs. Each figure shows the six frequencies used in this test. The results in these figures have

been normalized to the peak received signal at their respective frequencies. The peak values

occurred at the line-of-sight reference location. Figures 26 and 28 correspond to horizontally

polarized receiving antennas, while Figure 27 corresponds to vertically polarized antennas. The

stadium was actively being demolished with heavy machinery as these experiments were being

performed and our access to the stadium was limited. As a resuh, our time inside the structure was limited to safe periods when the equipment was idle, usually only during the operators'

lunch break or quiet periods when the machines required maintenance. Thus, the data in the

experiment were obtained in the following manner such that our time in the stadium was

minimized. First, an all-terrain-vehicle (ATV) was used to haul the transmitters through the

stadium. The receiving antennas were initially aligned in a horizontally polarized direction. The

transmitters were placed in the ATV and powered on at a light-of-sight reference location outside

the stadium. Once a baseline of data was recorded, the ATV was driven in and throughout the

upper levels of the stadium. Once the ATV was at the highest level in the stadium (called Level

700) we stopped the ATV at a location where the receiving antennas could be seen. At that point

the transmitters were powered off. The receiving antennas were then rotated to a vertically

polarized alignment. The transmitters were then energized and we drove the ATV back,

retracing its track to the exterior of the stadium. This sequence was repeated into the lower

levels of the stadium and onto the playing field. However, since there was no visible reference

to the receivers in the lower levels where we could flip polarizations, we chose to use one of the

sites that would be used to cache transmitters during the implosion (Site A) as our turn-around

location. As before, the transmitters were powered off, the receiving antennas rotated to a horizontally polarized alignment, and the ATV retraced its track to the exterior of the stadium.

From the graphs in Figures 26-28, we can see a large variability in the received signal as the

transmitters were moved throughout the building. These results show that the building induced

about 50 to 60 dB of shielding of the signals. This 50 to 60 dB indicates the additional design

margins that would be required in a link budget analysis of a communication system in order to achieve communication into a large building of this type.

7.2 Radio Mapping of Stadium: Statistical Distributions of Signal Strength

The results in the previous section illustrate that the field strengths varied by as much as 60 dB

throughout the stadium and 75 dB around the outside of the stadium. In communication systems

design, the variability of the field strength is as important as the field strength itself Knowing the

variability allows the system designer to develop devices for first responders that must be

capable of operating in an environment with large dynamic range in signal strength. In this

11
section, some statistics of the field strength variability inside and outside the stadium are

investigated. The first set of data analyzed was collected when we carried the transmitters

around the perimeter of the stadium (data in Figures 24 and 25). The histograms (2 dB bin size)

for this dataset are shown in Figure 29 and 30, for vertically and horizontally polarized receiving

antennas, respectively. Tables 6 and 7 summarize the mean received signal strength and the

standard deviation for each frequency.

The next set of data was collected when the transmitters were driven through the upper levels of

the stadium for horizontally polarized receiving antennas (data in Figure 26). The histograms for

this dataset are shown in Figure 3 1 . Table 8 summarizes the mean received signal strength and

the standard deviation for each frequency.

The next set of data was collected when the transmitters were driven through the upper levels of

the stadium to the playing field for vertically polarized receiving antennas (data in Figure 27).

The histograms for this dataset are shown in Figure 32. Table 9 summarizes the mean received

signal strength and the standard deviation for each frequency.

The final set of data was obtained from driving through the lower levels and playing field for

horizontally polarized receiving antennas (data in Figure 28). The histograms for this dataset are shown in Figure 33. Table 10 summarizes the mean received signal strength and the standard

deviation for each frequency.

Table 6. Mean and standard deviation of the received signal strengths for the exterior

perimeter measurements for vertically polarized receiving antennas.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 -37.3 18.1

162.09 -50.0 19.9

225.30 -50.9 20.3

448.50 ^5.5 21.1

902.45 -47.9 22.2

1830.00 ^2.3 19.7

Table 7. Mean and standard deviation of the received signal strengths for the exterior

perimeter measurements for horizontally polarized receiving antennas.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 -28.0 15.5

162.09 -29.2 15.1

225.30 -34.2 18.3

448.50 -32.8 16.1

902.45 -36.9 17.3

1830.00 -39.0 17.4

12
Table 8. Mean and standard deviation of the received signal strengths for the upper level

measurements for horizontally polarized receiving antennas.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 -30.6 15.0

162.09 -34.4 15.2

225.30 -30.0 13.9

448.50 -33.5 14.4

902.45 -37.2 13.8

1830.00 ^3.6 12.0

Table 9. Mean and standard deviation of the received signal strengths throughout the

upper levels of the stadium to the playing field for vertically polarized receiving antenna.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 -32.9 14.1

162.09 -39.4 15.7

225.30 -34.4 13.5

448.50 -28.7 11.2

902.45 -27.3 11.3

1830.00 -26.6 9.5

Table 10. Mean and standard deviation of the received signal strengths for the lower levels

and the playing field for horizontally polarized receiving antenna.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 -43.4 8.5

162.09 -36.1 10.6

225.30 -39.7 9.7

448.50 -36.6 8.6

902.45 -52.7 12.8

1830.00 -31.3 7.4

7.3 Pre-implosion Radio Signal Measurements with Transmitters at Fixed Sites

Before the implosion, sets of transmitters were placed at three fixed sites and secured (see

Section 6 for details). In order to get an indication of the relative difference in signal strengths

for the transmitters at the four different fixed transmit sites, a set of baseline data was collected.

The data were collected by placing the transmitters at each of the four fixed transmitter sites and

measuring the received signals with the equipment on the mobile cart. The cart was pulled

around the perimeter of the stadium.

13
7.3.1 Signal-Strength Measurements for Fixed Sites

Figures 34 and 35 show the variabihty in the signal strength around the perimeter of the stadium

for all six frequencies for transmitters located at fixed Site A. These two figures are for vertically

and horizontally polarized receiving antennas, respectively. It should be noted that as the cart was pulled around the building, the antennas on the cart were always pointed toward the center

of the stadium. Figures 36 and 37 show the data in Figure 34 and 35 normalized with respect to the overall (either horizontal or vertical polarization) maximum received signal. That is, each

frequency is normalized to its maximum level for all data recorded during both perimeter travels

of the receiving cart. We should note that this normalization reference includes a certain

unknown amount of attenuation, caused by the structure between the transmit site and the

location of best coupling on the exterior perimeter, which we cannot remove. These two plots

show the relative variability in the signal strength as the cart is moved around the stadium. From

these plots, we see that the presence of the stadium causes the signal to vary by as much as 55 dB

around the stadium perimeter.

Figures 38 and 39 show the variability in the signal strength around the perimeter of the stadium

for all six frequencies for transmitters located at fixed Site B. These two figures are for vertically

and horizontally polarized receiving antennas, respectively. Again, as the cart was pulled around

the building, the antennas on the cart were always pointed toward the center of the stadium.

Figures 40 and 41 show the data in Figure 38 and 39 normalized with respect to the maximum

received signal. That is, each frequency is normalized to its maximum level as described above.

Figures 40 and 4 1 show the relative variability in the signal strength as the cart is moved around

the stadium. In these plots, we see that the presence of the stadium construction causes the signal

to vary by as much as 40 dB around the stadium perimeter.

Figures 42 and 43 show the variability in the signal strength around the perimeter of the stadium

for all six frequencies for transmitters located at fixed Site C. These two figures are for vertical

and horizontal polarized receiving antennas, respectively. As above, the antennas on the cart were always pointed toward the center of the stadium. Figures 44 and 45 show the data in Figure

42 and 43 normalized with respect to the maximum received signal. From these plots, we see that

the stadium causes the signal to vary by as much as 50 dB around the stadium perimeter.

Figures 46 and 47 show the variability in the signal strength around the perimeter of the stadium

for all six frequencies for transmitters located at fixed Site D. These two figures are for vertical

and horizontal polarized receiving antennas, respectively. Figures 48 and 49 show the data in

Figures 46 and 47 normalized with respect to the maximum received signal. These two plots

show the relative variability in the signal strength as the cart is moved around the stadium. We

see that the stadium causes the signal to vary by as much as 60 dB around the stadium perimeter.

14
7.3.2 Statistical Distributions of Signal Strength for Fixed Sites

The results in the previous section illustrate that the field strengths varied by as much as 60 dB

around the perimeter of the stadium. In this section, some statistics of the field strength

variability around the perimeter are investigated. The first set of data analyzed is for fixed

transmitter site A (data in Figures 34 and 35). The histograms (2 dB bin size) for this dataset are shown in Figures 50 and 51, for vertically and horizontally polarized receiving antennas,

respectively. Note the histograms were generated from the normalized data. This presents the

typical variability that would be seen for a communication system carried around the perimeter.

Tables 1 1 and 1 2 summarize the mean received signal strength and the standard deviation for

each frequency. Once again, this is not the attenuation resulting from coupling into the stadium,

but is the variability a communication system would experience.

The next set of data analyzed is for fixed transmitter site B (data in Figures 38 and 39). The

histograms (2 dB bin size) for this dataset are shown in Figures 52 and 53, for vertically and

horizontally polarized receiving antennas, respectively. Note the histograms were generated from

the normalized data. This would be the actual variability that would be seen for a communication

systems carried around the perimeter. Tables 13 and 14 summarize the mean received signal

strength and the standard deviation for each frequency.

The next set of data analyzed is for fixed transmitter site C (data in Figures 42 and 43). The

histograms (2 dB bin size) for this dataset are shown in Figures 54 and 55, for vertically and

horizontally receiving antennas, respectively. Note the histograms were generated from the

normalized data. Tables 1 5 and 1 6 summarize the mean received signal strength and the standard

deviation for each frequency.

The next set of data analyzed is for fixed transmitter site D (data in Figures 46 and 47). The

histograms (2 dB bin size) for this dataset are shown in Figures 56 and 57, for vertically and

horizontally polarized receiving antennas, respectively. Note the histograms were generated from

the normalized data. Tables 17 and 18 summarize the mean received signal strength and the

standard deviation for each frequency.

Table 11. Mean and standard deviation of the received signal strengths for Fixed

Transmitter Site A for vertically polarized receiving antennas.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 -31.7 8.0

162.09 ^4.4 12.2

225.30 ^4.3 13.1

448.50 -37.4 11.1

902.45 -27.4 8.9

1830.00 -25.5 6.7

15
Table 12. Mean and standard deviation of the received signal strengths for Fixed

Transmitter Site A for horizontally polarized receiving antennas.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 -32.3 8.4

162.09 -All 14.3

225.30 -'ill 12.8

448.50 -37.1 11.1

902.45 -29.0 10.0

1830.00 -27.0 8.2

Table 13. Mean and standard deviation of the received signal strengths for Fixed

Transmitter Site B for vertically polarized receiving antennas.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 -18.9 5.7

162.09 -17.3 7.8

225.30 -16.9 7.1 448.50 -14.3 6.7

902.45 -28.0 8.8

1830.00 -25.0 8.3

Table 14. Mean and standard deviation of the received signal strengths for Fixed

Transmitter Site B for horizontally polarized receiving antennas.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 -26.7 6.5

162.09 -24.9 7.5

225.30 -24.9 8.5

448.50 -15.1 5.5

902.45 -17.2 6.4

1830.00 -23.5 6.9

16
Table 15. Mean and standard deviation of the received signal strengths for Fixed

Transmitter Site C for vertically polarized receiving antennas.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 -30.4 8.2

162.09 -34.2 9.8

225.30 ^2.5 10.8

448.50 -38.1 8.6

902.45 -38.1 8.4

1830.00 -20.8 8.4

Table 16. Mean and standard deviation of the received signal strengths for Fixed

Transmitter Site C for horizontally polarized receiving antennas.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 -32.1 9.4

162.09 -36.8 11.1

225.30 -36.3 10.8

448.50 -29.7 7.6

902.45 -32.4 8.6

1830.00 -27.3 6.8

Table 17. Mean and standard deviation of the received signal strengths for Fixed

Transmitter Site D for vertically polarized receiving antennas.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 ^3.1 12.4

162.09 -49.3 13.2

225.30 ^4.1 13.6

448.50 -34.4 10.5

902.45 -32.6 9.5

1830.00 -31.3 8.8

17
Table 18. Mean and standard deviation of the received signal strengths for Fixed

Transmitter Site D for horizontally polarized receiving antennas.

Frequency (MHz) Mean (dB) Standard deviation (dB)

49.60 ^5.0 11.0

162.09 ^9.6 12.0

225.30 -50.9 10.8

448.50 ^2.2 9.2

902.45 -37.7 8.9

1830.00 -^2.1 7.7

7.4 Implosion Radio-Signal Measurements with Transmitters at Fixed Sites with

Fixed and Mobile Receiving Sites

On the day of the implosion, the fixed receiver sites discussed in Section 6 were assembled and

the data collection programs were turned on two hours before the implosion. The transmitters at the four fixed locations in the stadium (see discussion in Section 6) were also turned on two

hours before the implosion. Figures 58-61 show the pre- and post implosion data for the fixed

receiver located at Receiving Site 1 . Each of these four figures corresponds to one of the four

fixed transmitter sites. The implosion occurred at around 7 a.m., and this is indicated in the

figures by the abrupt change in the signal levels. This receiving site was closest to transmitting

Site A. This is seen in the figures by the fact the signal strengths in Figure 58 are higher than

those in Figures 59-61. Notice that the signal strengths for the 49.78 MHz transmitter in Figure

58 were very weak even before the implosion.

From Figure 59, it is seen that the 49.66 MHz transmitter was also very weak before the

implosion. Also, notice the impulsive nature of the 448.60 MHz transmitter in Figure 59. In this

experiment the transmitter was modulated using a Morse code generator as part of the debris

radiator tests. This modulated signal showed large variability in measured power on the

spectrum analyzer as evidenced by the spikes in Figure 59. The useful part for this experiment is the unmodulated lower baseline which corresponds well to the other frequencies. In Figure 60,

we see that the signal strength of all four transmitters from Site C change from the transmitters at Site A by nearly the same amount. The changes in the signals from Site D (Figure 61) are not

quite as dramatic as Site C but the event is clearly discemable.

Figures 62-65 show the pre- and post implosion data for the fixed receiver located at Receiving

Site 2. Each of these four figures corresponds to one of the four fixed transmitter sites. The

implosion occurred at around 7 a.m., and this is indicated in the figures by the dramatic change

in the signal levels. This receiving site was farthest from transmitting sites A, B, and C. There is a large portion of the stadium between transmitter sites A, B, and C and the receiver and we see

in Figures 62, 63, and 64 that signals from these transmitters are very weak. The spectrum

analyzer at this receiving site was a similar model to the one at site 1 and we see a similar

response to the modulated Morse code signal in Figure 63. Interesting results are observed in

Figure 65. These data are from the transmitters ui the upper level and closest to Receiving Site 2.

18
First, notice that the 49.60 MHz transmitter signal increases for a few moments during the

implosion then decreases to a value of -90 dBm. This can be explained by the fact that once part

of the stadium fell away the propagation path changed briefly before reaching a final condition.

Similar dynamics are seen for the 448.50 MHz transmitter.

Figures 66-69 show the pre- and post implosion data for the fixed receiver located at Receiving

Site 3. Each of these four figures con-esponds to one of the four fixed transmitter sites. Once

again, after the implosion occurred we see a dramatic change in the signal levels. The data in

these figures exhibited some interesting variations during the implosion. The implosion was

designed to have the stadium collapse in a circular manner, as seen in Figure 70. The implosion

lasted over 60 s. During the collapse, half the stadium fell away from the perspective of this

receiving site, and as a result this receiving site could see inside the stadium before it totally

collapsed. This is illustrated nicely in Figures 66, 67, and 69. This effect is not seen in Figure

68. This is a result of the positioning of the transmitters at Site C. At this transmitdng site, the

transmitters were below ground level and against a concrete wall backed by soil. This wall was

in the general direction of receiving site 3 and did not move during the implosion.

This implosion was designed to obtain a total collapse of the stadium, representing a worst-case

scenario for simulating first responder communications, as shown in the photographs in Figures

70-73. Figure 70 shows the stadium collapsing, Figures 71 and 72 show the stadium after the

implosion. And Figure 73 shows the change in the landscape as seen from each of the receiving

sites before and after the implosion.

After the implosion, the cart was used to move a receiving system around the perimeter of the

building to record the transmitted signals. Figure 74 shows the mobile cart being used for the

post-implosion measurements. The path used was generally the same path as that used in the cart measurements before the implosion. We collected three sets of measurement data. The first measurements were performed with the receiving antenna for the five higher frequency bands

horizontally polarized. Figures 75-78 show the receiver signal strengths for the transmitters at the four different transmitting sites, respectively. By comparing these figures to the results in

Figures 35, 39, 43, and 47 (the pre-implosion measurements), the effects of the stadium collapse on the signal strength can be investigated. In order to better compare the pre- and post-implosion

measurements, the two datasets are overlaid with respect to the GPS cart location. Figures 79-98

show the comparison of these datasets. In these comparisons, we see an additional 20 to 50 dB of

attenuation after the collapse.

The next two sets of measurements were performed with the receiving antenna for the five

higher frequency bands vertically polarized. Figures 99-102 show the receiver signal strengths

for the transmitters at the four different transmitting sites for the first set of vertical perimeter

measurements. While Figures 103-106 show the receiver signal strengths for the transmitters at the four different transmitting sites for the second set of vertical perimeter measurements; the

results for the two different vertically polarized measurements are basically the same. By

comparing these figures to the results in Figures 34, 38, 42, and 46 (the pre-implosion

measurements), the effect of the stadium collapse on the signal strength can be investigated.

Once again, in order to better compare the pre- and post-implosion measurements, the two

datasets are overlaid with respect to the GPS cart location. Figures 107-126 show the comparison

19
of these datasets. In these comparisons, we see additional 20 to 40 dB of an attenuation after the

collapse.

Thus, if someone were trapped under such a rubble pile and were trying to communicate with an emergency responder with a two-way radio or cell phone, their communication link would have

to overcome an additional 20 to 50 dB of attenuation .

7.5 Field Tests of the Debris Radiator Concept

As noted in Reference [5], electric field strength drops off rapidly as one moves away from a

transmitter. When line-of-sight conditions exist between transmitter and receiver, use of a standard single-element antenna on a handheld radio or cell phone poses no problem even at distances on the order of miles. However, inside buildings, signal attenuation (loss) and

multipath (reflected signals that interfere with the primary received signal) can reduce the usable

operating range of these radios to much shorter distances. For collapsed building scenarios, a dense pile of debris can reduce the electric field strength at a receiver by 50 dB or more [5],

making standard point-to-point communications difficult.

Our goal in testing the debris radiator concept is to investigate whether the use of metallic debris

found at the site of a building collapse or partial collapse can more efficiently guide a radiofrequency signal through the debris pile than a radio or cell phone's built-in antenna. In collapsed

building scenarios, a great deal of metallic debris is often present, including long metallic objects

such as conduit, wiring, and pipes. The goal of this study was to see whether received signal

levels could be improved by placing the existing transmit antenna within the proximity of the

metallic object.

Since the opportunity to select a suitable metallic object in an emergency scenario is an uncertain

condition, use of debris radiators is envisioned as a tool of last resort for someone trapped in the

debris pile. Optimally, one would choose as a debris radiator an object that runs unbroken from

the inside to the outside of a building and has suitable transmission properties, including its proximity to earth ground. Close proximity to earth ground can reduce the efficiency of the

radiator. Since the choice of debris radiator is quite open-ended and the propagation environment

is complicated, use of simulation studies to verify even simple problems would be

computationally exhaustive. We have opted for laboratory and field tests to investigate the debris

radiator concept. Our studies show that improvement in received signal level can range from

zero to several orders of magnitude when debris radiators are used.

To maximize our chances of a useful outcome at the Philadelphia stadium implosion, we

simulated the best-case scenario of a metallic object running continuously from a radio to a receive site by laying stranded steel cables from two of the transmit sites (in close proximity to the radios) to the edge of what would be the debris pile after implosion. Use of the pre-placed

cables meant that even if post-blast safety considerations kept us from getting close to the

collapsed building, we could still acquire useful data. Two cables were run, one from transmit

Site A and one from transmit Site B, as shown in Figure 4. Photos of the Cable 1 and Cable 2

receive sites are shown in Figures 22 and 23.

20
We measured the received signals both before and after the building implosion using a spectrum

analyzer. We compared reception using two receiving antenna scenarios. The first consisted of a

directional, log-periodic antenna with a gain of approximately ten (that is, the received signal in

the direction of the array was ten times stronger than with an omni-directional antenna). For the

second scenario, we attached the spectrum analyzer directly to the steel cables through an impedance tuner. These types of impedance tuners are available commercially for use in the

amateur radio bands. Connecting our spectrum analyzer to the cable through the tuner

maximized the coupling of the signal between the cable and the spectrum analyzer.

We measured signals at receive sites Cable 1 and Cable 2 (see Figure 4) in the 160 MHz,

220 MHz, and 450 MHz frequency bands from all four transmit sites. Figure 127 shows the postimplosion measurements being made at the Cable 1 and Cable 2 receive sites. We were able to receive signals from all four transmit sites at each of the two receive sites, indicating that the

attenuation caused by the stadium's debris pile was not as severe as we encountered in the New

Orleans implosion [5].

Table 19 shows the results of our measurements. Post-implosion measurements at locations close

to the debris pile show signal levels ranging from -55 to -129 dBm (approximately the noise

floor of our spectrum analyzer).

Just as we found in the New Orleans implosion experiment [5], Table 19 shows that use of the

directional receiving antenna in close proximity to the debris radiator generally resulted in a higher received signal level than that obtained in a direct connection. Cable reception ranged

from 9 to 27 dB lower than reception with the antenna. Use of a more highly directional antenna

could improve reception even further, but at the expense of having to aim the antenna more

precisely, a factor which should be considered during search and rescue operations.

The experiments discussed here demonstrate that the debris radiator concept may provide a "last resort" method for improving wireless communications for someone trapped in a void in a collapsed building. Experiments such as these give us an understanding of what conditions will

make debris radiators most effective. Further tests in the field and in the laboratory have been

carried out and will be discussed in subsequent publications.

21
Table 19. Summary of data collected from debris radiator experiments: Cable (C) is the

case where the receiver is connected directly to the metallic debris through an impedance

tuner, and Antenna (A) is the case where a directional antenna is connected to the receiver.

Cable 1 Cable 2

Frequency TX Cable (C) Antenna (A) Diff.(C-A) Cable (C) Antenna (A) Diff.(C-A)

(MHz) Site (dBm) (dBm) (dB) (dBm) (dBm) (dB)

A -101 -72 29 -129 -120 9

B -109 -102 7 -123 -103 20

162

C -119 -102 17 - ~ ~ D -94 -104 10 -110 -100 10 A -102 -80 22 ~ -126 ~

B -114 -91 23 -127 -100 27

225

C -122 -106 26 ~ ~ ~ D -102 -88 14 -108 -81 27

A -85 -55 30 -122 -108 14

450

B ~ — — — ~ ~

C -114 -93 21 - ~ -- D -112 -96 16 -113 -99 14

22
8. Recovery of Transmitters

After the implosion, the demolition contractor of the building recovered the transmitters so that

we could examine them to determine whether the implosion destroyed them. This was needed to ensure that in the case that a signal for one particular transmitter was not detected after the

implosion, non-detection of signals was a result of the signal attenuation through the rubble, not

a result of the transmitter being destroyed. All the transmitters that were recovered from the

stadium were in operational condition.

9. Summary of Results and Conclusion

This report summarized radio propagation measurements performed before, during, and after the

implosion of the Veterans' Stadium in Philadelphia, PA. Three different types of experiments were performed during this effort. The first set of data, radio mapping, was collected a few days

before the stadium was imploded. This involved carrying transmitters tuned to various

frequencies through the stadium while recording the received signal at a site located outside the

stadium as mentioned above. The purpose of these measurements was to investigate how the

signals at the different frequencies couple into the stadium and to determine the field strength

variability throughout the building. The results in this report indicate that the stadium caused

about 50 to 60 dB of attenuation of the signals. These attenuation numbers were obtained by

normalizing the signal to outside LOS values. Measurements around the outside perimeter of the

stadium were also performed, and the results indicate that a walk around the exterior of the

stadium would result in 70 to 75 dB of attenuation of the signals. Therefore, this 50 to 75 dB

indicates the additional design margins that may be required in a link budget analysis of a communication system in order to achieve communication into a large structure of this type.

The results in Section 7.1 illustrated that the field strengths varied significantly throughout the

stadium. In designing communication systems, the variability of the field strength is as important as the field strength itself. Some statistics of the field strength variability in the

stadium were also investigated. The results in Section 7.2 show how the mean and standard

deviation of the signals varied with both frequency and location in the building. These results

show that the mean attenuation due to the building ranged from 25 to 50 dB and the standard

deviation ranged from 7 to 16 dB, depending on frequency. These results indicate the variability

in signal level that a communication system might experience throughout a building of this type.

These numbers can be compared to the implosion experiment performed in a 13-floor apartment

building near New Orleans [5]. The results in the stadium are similar to those obtained in the

apartment building. However, the stadium offers about 20 dB more shielding (or large

attenuation) of the radio signals than that of the apartment biulding.

There are a number of other interesting studies and measurements published in the literature

related to the attenuation of radio-frequency signals into buildings and through building materials

[5, 8-17]. Many, if not most, of these studies concentrated on frequencies allocated to cellular

and personal communications systems near 850 and 1900 MHz and the higher gigahertz bands

using measurement scenarios that model some part of the commercial cellular network including

23
building interiors. While direct comparison of these results to our measurements is not possible,

since each building and experimental setup is different, we can comment generally on how our

data compare with the results in the literature.

A comprehensive review of earlier (pre- 1991) building attenuation studies is given by Molkdar

[10]. The author notes that the statistics of the received signal strengths depend strongly on the

structural design, building materials, and contents of the building. The surrounding environment

(i.e., adjacent structures) also had an effect. Results for building attenuation or penetration loss were tabulated for several distinct categories, including residential (-2 to 24 dB), office building

in suburban areas (1.5 to 36 dB), and office building in urban areas (2 to 38 dB). Again, these

results were for the higher cellular frequencies. Devasirvatham et al. [9] claimed that the

statistics of signal attenuation within the interior of a large commercial stone and masonry

building for four different frequencies (850 MHz, 1.9 GHz, 4.9 GHz, and 5.8 GHz) were nearly

the same. They reported path losses ranging from 20 dB to near 70 dB and standard deviations

from 3 to 9 dB. In more recent experiments, Ju et al. [11] show attenuation (path loss) between

locations within an office building ranging from 20 to 80 dB at 1 800 MHz with 15 to 35 dB from

floor to floor. Tamg et al. [12] measured attenuation between floors in another office structure ranging from 20 to 47 dB at 900 MHz. The attenuation values of Ju et al. and Tamg et al. are similar to our measurements, but again, the measurement setups are quite different.

Walker [13] measured attenuation into several different buildings at 850 MHz and showed

average attenuation that ranged from 15 to 20 dB with standard deviations ranging from 5 to

11 dB. These buildings were illuminated by multiple cellular transmitters at distant locations,

and the exterior and interior signal strength measurements were extensively averaged. Davidson

et al. [15] also measured building penetration loss using cellular base transmitters some distance

from the buildings (similar to Walker [13]). These measurements favored the side of the

building facing the transmitter. The mean attenuation of all the buildings measured was 10.8 dB

at 900 MHz and 10.2 dB at 1500 MHz, while standard deviations of 5.8 dB and 5.6 dB,

respectively. In similar measurements, Tanis et al. [15] reported attenuation ranging from 16 to 19 dB for 880 MHz and 1922 MHz. The measurements of Loew et al. [16] are more similar to our configuration. They measured the path loss from a street level transmitter near the building

(both line-of-sight and shadowed by another structure) to various points within multistory

commercial structures. These measurements showed mean attenuation of as much as 22 dB to 33 dB for 912 MHz and 1920 MHz for specific buildings. Standard deviations varied from 8.8

to 14.5 dB. In one of the few studies at the lower VHF frequencies, Rice [17] measured several

structures and reported a mean penetration loss of 24.8 dB at 35 MHz with a standard deviation

of 14 dB and 23 dB loss at 150 MHz with a standard deviation of 12 dB.

We see there is huge variability in the experimental setup and objectives, the definition of the

reference measurement, the building properties, and the surrounding environment in the various

studies of building penetration loss. However, there is a consistent message in the data, namely

that there is always some attenuating effect on the radio-frequency energy caused by the

building. This attenuation is usually on the order of 10 to 30 dB but in certain situations it can climb as high as 80 dB or more.

24
In the second type of data collection, radio transmitters were placed in four fixed sites throughout

the stadium interior. Signals received at listening stations exterior to the stadium were collected

before, during, and after the implosion. Our receiving sites in this case were both fixed and

mobile. A receiving system mounted on a modified garden cart was pulled around the perimeter

of the stadium both before and after the implosion, enabling direct comparison of signal strength

as a function of azimuth angle through the standing stadium and the resulting pile of rubble. The

implosion is indicated in the results by the dramatic change in the signal levels. In fact, the

results show that some signals experienced large amounts of attenuation, while other signals

increased during the implosion but then decreased to a final level. This is explained by the fact

that the stadium collapsed around the perimeter in a 60 second sequence. Hence, portions of the

structure had fallen out of the signal path for some period of time before the section directly

above the transmitter cache came down and effectively blocked the signals. Measurements for

the transmitters in the different sites were made before the implosion such that a pre- and postsignal strength comparison could be made. These results show that large amounts of stadium

rubble caused at least 30 to 50 dB of attenuation of the signal. Thus, if someone is trapped under

such a rubble pile and is trying to communicate with an emergency responder with a two-way

radio or cell phone, their communication link would have to overcome 30 to 50 dB of

attenuation.

It is interesting to note that the increases in signal attenuation after the collapse of the stadium were not as large as observed during the apartment building implosion (60 to 70 dB, see [5]).

This can be explained by the fact the stadium had such massive amounts of concrete and steel throughout the stadium that the signal propagating through the interior of the stadium behaved

similarly to the signal propagating through collapsed rubble piles.

The third set of data, referred to as "debris radiators," was collected by connecting instruments to the stadium rubble and by using a directional antenna connected to our instruments placed in

proximity of metallic debris. The purpose of this experiment was to investigate the probability of

detecting radio signals from transmitter(s) under the rubble that might couple onto these metal

objects and radiate signals to the edges of the rubble pile. Use of debris radiators may improve

reception of signals emitted from deep within a stadium in collapsed building or other weaksignal scenarios. The results show that use of the directional receive antenna in close proximity

to the debris radiator generally resulted in a higher received signal level than did use of direct

connection. However, at some frequencies and at some locations, direct connection to the

metallic debris yielded results comparable to that of the antenna. Through experiments such as

these, we are beginning to gain an understanding of what conditions make debris radiators more

effective. Further tests in the field and in the laboratory have been carried out and will be

discussed in subsequent publications.

The results in this report are the second in a series of reports detailing implosion experiments

performed by NIST in order to better understand the first responder' s radio propagation

environment and to investigate new methods for weak-signal detection. The first set of implosion

experiments was performed in an apartment building in New Orleans. The results of similar

implosion experiments performed at the Washington D.C. Convention Center are the subject of a separate report. Besides implosion experiments, NIST has also performed radio-mapping

experiments in various other large structures, including apartment and office buildings, sports

25
stadiums, stores, malls, hotels, a convention center, and warehouses. The results of the signalstrength measurements and statistical distribution for these radio-mapping experiments will also

be published separately.

This work was sponsored by the U.S. Department of Justice and the U.S. Department of

Homeland Security through the Office of Law Enforcement Standards of NIST. We thank

William Moore, Mike Casbon, Jim Santora, and Jim Morgan of Brandenburg and Steven R.

Pettigrew and Jeffrey S. Sizemore of Demolition Dynamics for their assistance during this

experiment. Without their help, this experiment would not have been possible. We also thank

members of the technical staff of the Electromagnetics Division 818, who pulled together the

equipment in a short time, including Dennis Friday, Perry Wilson, and Robert Judish for

managerial support.

26
10. References

[I] Statement of Requirements: Background on Public Safety Wireless Communications, The

SAFECOM Program, Department of Homeland Security, Vol. 1.0, March 10, 2004.

[2] M. Worrell and A. MacFarlane, Phoenix Fire Department Radio System Safety Project,

Phoenix Fire Dept. Final Report, Oct. 8, 2004,

http://www.ci.phoenix.az.us/FIRE/radioreport.pdf.

[3] 9/1 1 Commission Report, National Commission on Terrorist Attacks Upon the United

States, 2004.

[4] Final Report for September 11, 2001 New York World Trade Center terrorist attack.

Wireless Emergency Response Team (WERT), Oct. 2001.

[5] C.L. HoUoway, G. Koepke, D. Camell, K.A. Remley, D.F. Williams, S. Schima, S. Canales, and D.T. Tamura, "Propagation and Detection of Radio Signals Before, During

and After the Implosion of a Thirteen Story Apartment Building," NIST Technical Note

1540, Boulder, CO, May 2005.

[6] C.L. Holloway, G. Koepke, D. Camell, K.A. Remley, and D.F. Williams, "Radio

Propagation Measurements During a Building Collapse: Applications for First

Responders," Proc. Intl. Svmp. Advanced Radio Tech., Boulder, CO, March 2005, pp. 61-

63.

[7] APCO International, APCO Project 25 Standards for Public Safety Digital Radio, Aug.

1995, http://www.apcointl.Org/frequencv/proiect25/information.html#documents .

[8] Rubinstein, T.N., "Clutter losses and environmental noise characteristics associated with

various LULC categories," /£"££ Trans. Broadcasting, 44(3): 286-293; Sept. 1998.

[9] D.M.J. Devasirvatham, C. Banerjee, R.R. Murray, and D.A. Rappaport, "Four-frequency

radiowave propagation measurements of the indoor environment in a large metropolitan

commercial building," Proc. GLOBECOM 1991, Phoenix, AZ, 2-5 Dec. 1991, pp. 1282-

1286.

[10] D. Molkdar, "Review on radio propagation into and within building," lEE Proceeding-H,

38(1): 61-73; Feb. 1991.

[II] K.M. Ju, C.C. Chiang, H.S. Liaw, S.L. Her, "Radio propagation in office building at 1.8 GHz," Proc. 7" IEEE Intl. Symp. on Personal, Indoor and Mobile Radio

Communications, Taipei, 15-18 Oct., 1996, pp. 766-770.

27
[12] J.H. Tamg and D.W. Pemg, "Modeling and measurement of UHF radio propagating

through floors in a multifloored building," Proc. lEE, Microwave Antennas Propagat.,

144(5): 359-363; Oct. 1997.

[13] E. Walker, "Penetration of radio signals into building in the cellular radio environment,"

BellSyst. Tech. J., 62(9), Nov. 1983.

[14] A. Davidson and C. Hill, "Measurement of building penetration into medium buildings at 900 and XSOQ MRzr IEEE Trans. Veh. TechnoL, 46(1): 161-168; Feb. 1997.

[15] W.J. Tanis and G.J. Pilato, "Building penetration characteristics of 880 MHz and 1922

MHz radio waves," Proc. 43th IEEE Veh. Technol Conf., Secaucus, NJ, 18-20 May

1993, pp. 206-209.

[16] L.H. Loew, Y. Lo, M.G. Lafin, and E.E. Pol, "Building penetration measurements from

low-height base stations at 912, 1920, and 5990 MHz," NTIA Report 95-325, National

Telecommunications and Information Administration, Sept. 1995.

[17] L.P. Rice, "Radio transmission into buildings at 35 and 150 mc," Bell Syst. Tech. J., pp.

197-210, Jan. 1959.

28
^1

Figure 1. Veterans' Stadium.

29
Figure 2. Pre-implosion deconstruction of the stadium.

30
J

1

m

II ^^P

II

^

?1

1

1 W

1

|H

it 1 E^arj- ILjyti

pR^Q

] c

*^

Figure 3. Pre-implosion preparation inside the stadium.

31
Cable 2 TXB

TXD

RX2

PATTISON AVENUE

T ^^Tl

Figure 4. Stadium overview. TX refers to the transmitter locations and RX refers to the receiver

locations during the implosion. The cable locations for the debris radiator tests are also noted on

the drawing.

32
Figure 5. Typical transmitters used for the lower four frequency bands.

» ^ • • c

Hi H Wi M tt tl

Figure 6. Transmitters used for the two higher frequency bands.

33
Figure 7. Transmitter in the NIST Boulder anechoic chamber.

34
( ^ -16 — Plane 1 Plane 2 ^ Front or Top of Box

-17 —

-18 —

-19 —

-20 —

-21 —

^ )

/ ^—^^

'"'^\/~--^^_

N^^

V

2,

-22 —

J

ty. -23 —

-24 —

-25 —

-26 —

-27 —

-28 —

-29 —

on

1

1

1 11

I

1

'

1 '

1

1

1

1 1

I

>

1

1

1

1

30 60 90 120 150 180 210 240 270 300 330 360 Angle (degrees)

Figure 8. Radiation pattern of a 164 MHz transmitter in a protective case.

Front or Top of Box

30 60 90 120 150 180 210 240 270 300 330 360 Angle (degrees)

Figure 9. Radiation pattern of a 225 MHz transmitter in a protective case.

35
- lo —

-20 — /'^ ^-^ ^ Front or Top of Box

-22 — \ ^^ ,^ ^s

-24 — /

-26 — ,-^- i \ •^ "^. / -28 —

-30 —

\

\

-32 —

-34 —

A- ^^ m-** , -36 —

"^^--vT

^

PT ^^^^ J*-" -38 — TT'"*^^^-*-*^^ *v r CD2, -40 — / \ \

y-'^~^^ f — / M -42 — / \ • / jK.

LLI_ -44 —

-46 —

' v

-48 —

\ l\ /\ r N \\ / \J

-50 — r->i A / -52 — Plane 2 u / -54 —

1 / -56 — ^

\ 1 -58 — 1 1 -60 — W

-62 — 1/

C/1 1 -D4 —

'

1

>

1

1

{

1

1

1

1

' 1 11

1

1

1

1

1

1

1

1

30 60 90 120 150 180 210 240 270 300 330 360 Angle (degrees)

Figure 10. Radiation pattern of a 448 MHz transmitter in a protective case.

36
900 MHz

Yagi Antenna

Antenna Mast installed in TRIPOD or CART

Portable Spectrum Analyzer

Figure 1 1 . Schematic of the receiving system for the building penetration and field-mapping

experiments.

37
Figure 12. Photos of the weather-resistant antenna system mounted on a tripod and mounted to the mobile cart. The receiving instruments are protected inside the container in the tripod system

and under the plastic in the cart system.

38
^^>^^^JHHHhH^^H

- Ji =^i

^k. —

Figure 13. Receiving site on the south perimeter of the stadium.

39
Figure 14. Carrying and driving transmitters through the stadium.

40
Figure 15. Fixed transmitter location TX A on south-side of sub-level.

41
Figure 16. Fixed transmitter location TX B on the playing field.

42
Figure 17. Fixed transmitter location TX C on west side of sub-level.

43
i

1 inin1 1^ 1

B9EI&

11

'm 1

1

f^l^^HB^P^^

^^^r^^T^ySf^

'

Figure 18. Fixed transmitter location TX D on the third level.

44
(a) (b)

(c) (d)

Figure 19. Final installation of transmitters with protective blast cloth; (a) south wall: TX A

location, (b) playing field: TX B location, (c) west wall: TX C location, and (d) third level in

tumstyle: TX D location.

45
(a)

Figure 20(a). Fixed receiving site RX 1 : south-west site (unstaffed site, 53 m away).

46
(b)

Figure 20(b). Fixed receiving site RX 2: south-east site (unstaffed, 37 m away).

47
(c)

Figure 20(c). Fixed receiving site RX 3: north-west site (unstaffed, 53 m away).

48
Figure 2 1 . Mobile measurement cart.

49
Cable near transmitters

/. I

Figure 22. Cable on north side of stadium. This cable was run from the transmitter site on the

playing field (TX B).

50
Cable near transmitters

-•XV.

Figure 23. Cable on south side of stadium. This cable was run from the transmitter site at the

south wall (TX A).

51
80 100 120 140 Data file location 160 180

Figure 24. Stadium perimeter walk around for vertically polarized receiving antennas.

20 40 60 80 100 120 140 160 Data file location

Figure 25. Stadium perimeter walk around for horizontally polarized receiving antennas.

52
-10 —

-20 —

-30 _ -40 na

fe -50 H

o^ -60 H

-70 —

-80

-90 —I

-100

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

20 40 60 80 100 120 140 160 180 200 Data file location

Figure 26. Stadium walk-through for horizontally polarized receiving antennas.

CD^

^_

s:o

CL

-80

-90 —

-100

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

I

I

I

I

I II

I II

I I

20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 Data file location

Figure 27. Stadium walk-through for vertically polarized receiving antennas.

53
-70

-80

-90

-100

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

40 80 120 160 200 240 280 320 360 400 440 480 Data file location

Figure 28. Stadium walk-through for horizontally polarized receiving antennas (playing field).

54
Frequency: 49.6 MHZ

Mean: -37.3 StdDev: 18.1

(a)

Frequency: 225.3 MHz

Mean: -50.9 Std Dev: 20.3

-90 -80 -70 -60 -50 -10 -30 -20 -10 Power (dB)

(c)

Frequency: 162.09 MHz

Mean: -50.0 StdDev: 19.9

-90 -80 -70 -60 -50 -40 -30 -20 -10 Power (dB) (b)

Frequency: 448.5 MHz

Mean: -45.5 Std Dev: 21.1

(d)

Frequency: 902.45 MHz

Mean: -47.9 Std Dev: 22.2

Frequency: 1830 MHz

Mean: -42.3 StdDev: 19.7

-70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 Power (dB)

(e) (f)

Figure 29. Histograms for the perimeter measurements for vertically polarized receiving

antennas.

55
Frequency: 49.6 MHz

Mean: -28.0 Std Dev: 15.5

-48 -M -40 -36 -32 -28 -24 -20 -16 -12 Power (dB)

(a)

Frequency: 162.09 MHz

Mean: -29.2 Std Dev: 15.1

-65 -60 -55 -50 ^5 -40 -35 -30 -25 -20 -15 -10 -5 Power (dB) (b)

Frequency: 225.3 MHz

Mean: -34.2 Std Dev: 18.3

I

Frequency: 448.5 MHz

Mean: -32.8 Std Dev: 16.1

-56 -52 -48 -44 -40 -36 -32 -28 -24 -20 -16 -12 -8-4

Power (dB)

-60 -56 -52 -48 ^14 ^0 -36 -32 -28 -24 -20 -16 -12 -8-4

Power (dB)

(c) (d)

Frequency: 902.45 MHz

Mean: -36.9 Std Dev: 17.3

•56 -52 -48 -44 -40 -36 -32 -28 -24 -20-16-12-8 -4 Power (dB)

-60 -56 -52 -48 -44 ^0 -36 -32 -28 -24 -20 -16 -12 -8-10

Power (dB)

(e) (f)

Figure 30. Histograms for the perimeter measurements for horizontally polarized receiving

antennas.

56
Frequency: 49.6 MHz

Mean: -30.6 Std Dev: 15.0

I '

I

'

I 'I 100 -90 -80 -70 -60 5u Power (dB)

(a)

Frequency: 162.09 MHz

Mean: -34.4 Std Dev: 15.2

(b)

I 'I 100 -90 -80 -70 -60 -50 -40 -30 -20 -10 Power (dB)

Frequency: 225.3 MHz

Mean: -30.0 Std Dev: 13.9

I

'

I

'

i

'

I 100 -90 -80 -70 -60 -50 -40 -30 -20 -10 Power (dB)

Frequency; 448.5 MHz

Mean: -33,5 Std Dev: 14.4

I

' I'

i -100 -90 -80 -70 -60 -50 ^0 -30 -20 -10 Power (dB)

(c) (d)

Frequency: 902.45 MHz

Mean: -37.2 Std Dev: 13.8

I 'I

'

I ' 100 -90 -80 -70 -60 -50 -10 -30 -20 -10 Power (dB)

Frequency: 1830 MHz

Mean: -43.6 Std Dev: 12.0

-100 -90 -80 -70 -60 -50 -10 -30 -20 -10 Power (dB)

(e) (f)

Figure 3 1 . Histograms for the upper level measurements for horizontally polarized receiving

antennas.

57
-60 -55 -50 ^5 -40 -35 -30 -25 -20 -15 -10 -5 Power (dB)

Frequency: 162.09 MHz

Mean: -39.4 StdDev:15.7

Power (dB) (b)

Frequency: 448.5 MHz

Mean: -28.7 StdDev: 11.2

-56 -52 -48 -44 -40 -36 -32 -28 -24 -20 -16 -12-8-4

Power (dB)

(c) (d)

Frequency: 902.45 MHz

Mean: -27.3 StdDev: 11.3

-56 -52 -48 -44 -40 -36 -32 -28 -24 -20 -16 -12 Power (dB)

-8 -4

(e)

I

Frequency: 1830 MHz

Mean: -26.6 Std Dev: 9.5 <

p-

! i

1

I M M I

'

I

'

I

' i'

I

'

I

'

I

'

-40 -36 -32 -28 -24 -20 -16 -12 -8 -4 Power (dB)

(f)

Figure 32. Histograms for data collected throughout the upper levels of the stadium to the play

field for vertically polarized receiving antennas.

58
Frequency: 49.6 MHz

Mean: -43.4 Std Dev: 8.5

Frequency: 162.09 MHz

Mean: -36.1 Std Dev: 10.6

-60 -56 -52 -48 -44 -40 -36 -32 -28 -24 -20 -16 -12 -8-4

Power (dB) (b)

Frequency: 225.3 MHz

Mean: -39.7 Std Dev: 9.4

Frequency: 448.5 MHz

Mean: -36.6 Std Dev: 8.6

-55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 Power (dB)

(c) (d)

Frequency: 902.45 MHz

Mean: -52.7 Std Dev: 12.8

I

' M I M

-75 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 Power (dB) (e)

Frequency: 1830 MHz

Mean: -21.3 Std Dev: 7.4

I

'

I M ' I

'

I

'

-65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 Power (dB) (f)

Figure 33. Histograms for data collected for the lower levels and the play field for horizontally

polarized receiving antennas.

59
-40

-50

-60 —

m -70 —

CD £ -80

-90 —

-100 —

-110

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

40 80 120 160 200 240 280 320 360 400 Data file location

Figure 34. Signal strength measurements around the perimeter of the stadium for the transmitters

located at fixed Site A and vertically polarized receiving antennas.

-40

00

o

a.

-50 —

-60

-70 —

-80 —

-90

-100

-110

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

40 80 120 160 200 240 280 Data file location 320

Figure 35. Signal strength measurements around the perimeter of the stadium for the transmitters

located at fixed Site A and horizontally polarized receiving antennas.

60
D

O

a.

-10

-20

-30 —

-40

-50 —

-60

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

'

I 'I

'

I

'

I

'

I

'

I

'

i

'

I

'

I

' 40 80 120 160 200 240 280 320 360 400 Data file location

Figure 36. Normalized signal strength for the perimeter measurements of the stadium for the

transmitters located at fixed Site A and vertically polarized receiving antennas.

-10

-20

CD

fe -30 o

D.

-40

-50

-60

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 ^l^^

40 80 120 160 200 240 280 320 Data file location

Figure 37. Normalized signal strength for the perimeter measurements of the stadium for the

transmitters located at fixed Site A and horizontally polarized receiving antennas.

61
-30

-40

COo

o

CL

-50 —

-60

-70 —

-80

-90 —

-100

-110

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

40 80 120 160 200 Data file location 240 280

Figure 38. Signal strength measurements around the perimeter of the stadium for the transmitters

located at fixed Site B and vertically polarized receiving antennas.

-30

-40

-50

-60 —

m

-70 o

CL -80

-90 —

-100

-110

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

40 80 120 160 Data file location 200 240

Figure 39. Signal strength measurements around the perimeter of the stadium for the transmitters

located at fixed Site B and horizontally polarized receiving antennas.

62
120 160 Data file location 280

Figure 40. Normalized signal strength for the perimeter measurements of the stadium for the

transmitters located at fixed Site B and vertically polarized receiving antennas.

-10

-20 —

COo

fc -30 o

-40

-50

-60

^^\.^fc-K^f^

40 80

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

120 160 Data file location 200 240

Figure 41. Normalized signal strength for the perimeter measurements of the stadium for the

transmitters located at fixed Site B and horizontally polarized receiving antennas.

63
-40

-50

-60

00 -70

TJ

i-o

5o

Q. -80

-90

-100

-110

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

40 80 120 160 Data file location 200 240

Figure 42. Signal strength measurements around the perimeter of the stadium for the transmitters

located at fixed Site C and vertically polarized receiving antennas.

-60

-70

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

ca

I—

CDO

Q.

-100 —

-110

80 100 120 140 160 180 200 220 240 260 Data file location

Figure 43. Signal strength measurements around the perimeter of the stadium for the transmitters

located at fixed Site C and horizontally polarized receiving antennas.

64
-60

-70

-80

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

T" 40 80 120 160 Data file location 200 240

Figure 44. Normalized signal strength for the perimeter measurements of the stadium for the

transmitters located at fixed Site C and vertically polarized receiving antennas.

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

80 100 120 140 160 180 200 220 240 260 Data file location

Figure 45. Normalized signal strength for the perimeter measurements of the stadium for the

transmitters located at fixed Site C and horizontally polarized receiving antennas.

65
-20

-30 —

-40

-50

^ -60

O -70

-80

-90

-100

-110

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

20 40 60 80 100 120 140 160 180 Data file location

Figure 46. Signal strength measurements around the perimeter of the stadium for the transmitters

located at fixed Site D and vertically polarized receiving antennas.

-20

-30

-40

-50

0)o -70 —\

a.

-80

-90

-100

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

'^^°

i

' I'

I

'

I

' I'

I

'

I

' I

'

I 'I ' 20 40 60 80 100 120 140 160 180 200 Data file location

Figure 47. Signal strength measurements around the perimeter of the stadium for the transmitters

located at fixed Site D and horizontally polarized receiving antennas.

66
60 80 100 120 140 160 180 Data file location

Figure 48. Normalized signal strength for the perimeter measurements of the stadium for the

transmitters located at fixed Site D and vertically polarized receiving antennas.

-10

-20

-30

T3 -40 o

Q. -50

-60

-70

-80

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

902.45 MHz

1830.0 MHz

20 40 60 80 100 120 140 160 180 200 Data file location Figure 49. Normalized signal strength for the perimeter measurements of the stadium for the

transmitters located at fixed Site D and horizontally polarized receiving antennas.

67
Frequency: 49.6 MHz

Mean: -31.7 Std Dev: 8.0

(a)

Frequency: 162.09 MHz

Mean: -44.4 Std Dev: 12.2

H'^ P'l ^ M

•56 -52 -18 -M -40 -36 -32 -28 -24 -20 -16 -12-8-4

Power (dB)

(b)

Frequency: 225.3 MHz

Mean: -44.3 Std Dev: 13.1

-56 -52 -48

Ilii

-44 ^0 -36 -32 4-28 -24 -20 -16 -12 -8-4

Power (dB)

(c)

Frequency: 448.5 MHz

Mean: -37.4 Std Dev: 11.1

n I '! I

I n

-52 -18 -M -40 -36 -32 -28 -24 -20 -16 -12 -8-10

Power (dB) (d)

Frequency: 162.09 MHz

Mean: -41.7 Std Dev: 14.3

-60 -56 -52 -18 -14 -10 -36 -32 -28 -24 -20 -16 -12 -8-4

Power (dB)

Frequency: 49.6 MHz

Mean: -32.3 Std Dev: 8.4

(e) (f)

Figure 50. Histograms for the perimeter measurements for Site A fixed transmitters and

vertically polarized receiving antennas.

68
Frequency: 49.6 MHz

Mean: -32.3 Std Dev: 8.4

44 -40 -36 -32 -28 -24 -20 -16 -12 Power (dB)

Frequency: 162.09 MHz

Mean: -41.7 Std Dev: 14.3

-60 -56 -52 -48 -44 -10 -36 -32 -28 -24 -20 -16 -12 -8-4

Power (dB)

(a) (b)

Frequency: 225.3 MHz

Mean: -37.2 Std Dev: 12.8

(C)

Frequency: 448.5 MHz

Mean: -37.1 Std Dev: 11.1

-56 -52 -48 -40 -36 -32 -28 -24 -20 -16 -12 -8-4

Power (dB)

(d)

(e) (f) Figure 5 1 . Histograms for the perimeter measurements for Site A fixed transmitters and

horizontally polarized receiving antennas.

69
Frequency: 448.5 MHz

Mean: -15.1 Std Dev: 5.5 I

1^""^

-24 -20 -16 -12 Power (dB)

(a)

Frequency: 162.09 MHz

Mean: -17.3 Std Dev: 7.8

h I ^H

- 1^^^

Power (dB) (b)

-48 -44 -40 -36 -32 -28 -24 -20 -16 -12 -8-4

Frequency: 225.3 MHz_

Mean: -16.9 I

Std Dev: 7.1

40 ^-36 -32 -28 -24 -20 -16 -12 Power (dB)

(c)

Frequency: 448.5 MHz

Mean: -14.3 Std Dev: 6.7 I

-pais|s^s^

-40 -36 -32 -28 -24 -20 -16 -12 Power (dB)

(d)

I

Frequency: 49.6 MHz

Mean: -26.7 Std Dev: 6.5

-32 -28 -24 -20 -16 Power (dB)

-Z4 -20 -16 -12 Power (dB)

(e) (f) Figure 52. Histograms for the perimeter measurements for Site B fixed transmitters and

vertically polarized receiving antennas.

70
(a)

Frequency: 225.3 MHz

Mean: -24.9 Std Dev: 8.5

(C)

Frequency: 902.45 MHz

Mean: -17.2 Std Dev: 6.4

BBS

-44 -40 -36 -32 -28 -24 -20 -16 -12 -8^0

Power (dB) (b)

Frequency: 448.5 MHz

Mean: -15.1 Std Dev: 5.5 I

-32 -28 -24 -20 -16 -12 Power (dB)

(d)

Frequency: 1830 MHz

Mean: -23.5 Std Dev: 6.9

(e) (f) Figure 53. Histograms for the perimeter measurements for Site B fixed transmitters and

horizontally polarized receiving antennas.

71
Frequency: 162.09 MHz

Mean: -34.2 Std Dev: 9.8

-18 -44 -40 -36 -32 -28 -24 20 -16 -12 -8-4

Power (dB) (a) (b)

-52 ^8 -44 -40 -36 -32 -28 -24 -20 -16 -12 -8 -4 Power (dB) ^ -36 -32 -28 -24 -20 -16 -12 -8^0 Power (dB)

(c) (d)

Frequency: 162.09MHz Frequency: 49.6 MHz

Mean: -36.8 60 — 1 Mean: -32.1 Std Dev: 11.1

40 — L

z 1i

^^^^^^^^^^Pt"^ n nn ^

20 —

-52 -48 -M -40 -36 -32Power-28 (dB)-24 -20 -16 -12 -8 -4 ( —

^L-. -36 -32 -28 -24 -20 -16 -12 -8-4

Power (dB)

(e) (f)

Figure 54. Histograms for the perimeter measurements for Site C fixed transmitters and

vertically polarized receiving antennas.

72
-40 -36 -32 -24 -20 -16 -12 Power (dB)

(a)

Frequency: 162.09MHz

Mean: -36.8 StdDev: 11.1

(b)

Frequency: 225.3 MHz

Mean: -36.3 StdDev: 10.8

(C)

Frequency: 448.5 MHz

Mean: -29.7 Std Dev: 7.6

I

'

i -40 -36 -32 -28 -24 -20 -16 -12 Power (dB)

(d)

Frequency: 49.6 MHz

Mean: -43.1 Std Dev: 12.4

I '

I

'

I

'

I

'

I

'

I

' I'

I

'

I

'

I

'

I

'

1

'

I 70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 Power (dB)

Frequency: 162.09 MHz

Mean: -49.3

StdDev: 13.2

I

' I' r I '

I 'I

'

I

' I'

I

'

I

'

I

'

I

'

I -75 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 Power (dB)

(e) (f)

Figure 55. Histograms for the perimeter measurements for Site C fixed transmitters and

horizontally polarized receiving antennas.

73
Frequency: 49.6 MHz

Mean: -43.1 StdDev: 12.4

-70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 Power (dB)

-75 -70 -65 -60 -55 -50 -45 -40 -35 -30 25 -20 -15 -10 -5 Power (dB) (a) (b)

Frequency: 225.3 MHz

Mean: -44.1 Std Dev: 13.6

(C)

Frequency: 902.45 MHz

Mean: -32.6 Std Dev: 9.5

•56 -52 -48 -40 -36 -32 -28 -24 -20 -16 -12-8-4

Power (dB)

(d)

-60 -56 -52 -46 -44 ^0 -36 -32 -28 -24 -20 -16 -12 -8-4

Power (dB)

(e) (f) Figure 56. Histograms for the perimeter measurements for Site D fixed transmitters and

vertically polarized receiving antennas.

74
Frequency: 49.6 MHz

Mean: -45.0 Std Dev: 11.0

liiiKJiliiti__

-70 -65 -60 -55 -50 -45 JlO -35 -30 -25 -20 -15 -10 -5 Power (dB)

(a)

30 -^

Frequency: 162.09 MHz

Mean: -49.6 Std Dev: 12.0

1

2 20 —

1

'

1

10 —

—

,:' M,

1

-70 -65 -60 -55 -50 -45 JlO -35 -30 -25 -20 -15 -10 -5 Power (dB)

(b)

Frequency: 225.3 MHz

Mean: -50.9

Std Dev: 10.8

"PT

-70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 Power (dB)

(c)

Frequency: 448.5 MHz

Mean: -42.2 Std Dev: 9.2

ii rTHM^" -60 -56 -52 -48 ^14 ^0 -36 -32 -28 -24 -20 -16 -12 -8^0

Power (dB)

(d)

Frequency: 902.45 MHz

Mean: -37.7 Std Dev: 8.9

h

-60 -56 -52 -48 -44 ^0 -36 -32 -28 -24 -20 -16 -12 -8 -4 Power (dB)

-60 -56 -52 -48 -44 -40 -36 -32 -28 -24 -20 -16-12 -8 -4 Power (dB)

(e) (f)

Figure 57. Histograms for the perimeter measurements for Site D fixed transmitters and

horizontally polarized receiving antennas.

75
-50

-60 /TM^r%Vv%A tr -80

' 49.78 MHz

162.20 MHz

226.50 MHz

448.80 MHz

902.45 MHz

1830.00 MHz

-110

6:50:08 AM 6:52:53 AM 6:55:38 AM 6:58:23 AM 7:01:07 AM 7:03:52 AM 7:06:37 AM 7:09:22 AM

Time

Figure 58. Pre- and post-implosion data collected from Receiver Site 1 for the transmitters

located at Site A.

-30

-40

-50

-60

-90

-100

-110

— 49.66 MHz — 163.30 MHz

225.40 MHz

448.60 MHz

902.60 MHz

1831.00 MHz

, / r 1

i

1

miM

)$ naRMm/ *, ^

M\^^

4

t^QsfSJwv^

I

)ff--J ^

v^^ wry

6:50:08 AM 6:52:53 AM 6:55:38 AM 6:58:23 AM 7:01:07 AM 7:03:52 AM 7:06:37 AM 7:09:22 AM

Time

Figure 59. Pre- and post-implosion data collected from Receiver Site 1 for the transmitters

located at Site B.

76
-50

-60

-70

-80

-90

-100

49.72 MHz

165.54 MHz

226.40 MHz

448.70 MHz iMffltstor^ viWn W*BMvV"' ^M

r-WM

1

I

1 WWI^^ra \l ''VW V

' ' ' 'V 1 v

' w • \ym - ~^

6:50:08 AM 6:52:53 AM 6:55:38 AM 6:58:23 AM 7:01:07 AM 7:03:52 AM 7:06:37 AM 7:09:22 AM

Time

Figure 60. Pre- and post-implosion data collected from Receiver Site 1 for the transmitters

located at Site C.

-50

-60

-70

-90

-100

49.60 MHz

162.90 MHz

225.30 MHz

448.50 MHz

f^ Y'M^'i'vVY^* rt "IfP^TY^:p^^Ya)^pi^^^^

^'AV^YwvWMW mdm^

-110

6:50:08 AM 6:52:53 AM 6:55:38 AM 6:58:23 AM 7:01:07 AM 7:03:52 AM 7:06:37 AM 7:09:22 AM

Time

Figure 61. Pre- and post-implosion data collected from Receiver Site 1 for the transmitters

located at Site D.

77
-75

-100

49.78 MHz

162.20 MHz

226.50 MHz

448.80 MHz

902.45 MHz

1830.00 MHz

^ft-i^^^/y^^

6:50:02 AM 6:52:38 AM 6:55:14 AM 6:57:50 AM 7:00:28 AM 7:03:05 AM 7:05:41AM 7:08:18 AM

Time

Figure 62. Pre- and post-implosion data collected from Receiver Site 2 for the transmitters

located at Site A.

6:52:38 AM 6:55:14 AM 6:57:50 AM 7:00:28 AM

Time

7:03:05 AM 7:05:41AM 7:08:18 AM

Figure 63. Pre- and post-implosion data collected from Receiver Site 2 for the transmitters

located at Site B.

78
6:50:02 AM 6:52:38 AM 6:55:14 AM 6:57:50 AM 7:00:28 AM 7:03:05 AM 7:05:41AM 7:08:18 AM

Time

Figure 64. Pre- and post-implosion data collected from Receiver Site 2 for the transmitters

located at Site C.

-110

6:50:02 AM 6:52:38 AM 6:55:14 AM 6:57:50 AM 7:00:28 AM 7:03:05 AM 7:05:41AM 7:08:18 AM

Time

Figure 65. Pre- and post-implosion data collected from Receiver Site 2 for the transmitters

located at Site D.

79
6:50:02 AM 6:52:10 AM 6:54:17 AM 6:56:24 AM 6:58:31AM 7:00:38 AM 7:02:45 AM 7:04:52 AM 7:06:59 AM 7:09:06 AM

Time

Figure 66. Pre- and post-implosion data collected from Receiver Site 3 for the transmitters

located at Site A.

• 49.66 MHz

• 163.30 MHz

• 225.40 MHz

448.60 MHz

902.60 MHz

1831.00 MHz

6:50:02 AM 6:52:10 AM 6:54:17 AM 6:56:24 AM 6:58:31AM 7:00:38 AM 7:02:45 AM 7:04:52 AM 7:06:59 AM 7:09:06 AM

Time

Figure 67. Pre- and post-implosion data collected from Receiver Site 3 for the transmitters

located at Site B.

80
49.72 MHz

165.54 MHz

226.40 MHz

' 448.70 MHz

6:50:02 AM 6:52:10 AM 6:54:17 AM 6:56:24 AM 6:58:31AM 7:00:38 AM 7:02:45 AM 7:04:52 AM 7:06:59 AM 7:09:06 AM

Time

Figure 68. Pre- and post-implosion data collected from Receiver Site 3 for the transmitters

located at Site C.

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

6:50:02 AM 6:52:10 AM 6:54:17 AM 6:56:24 AM 6:58:31AM 7:00:38 AM 7:02:45 AM 7:04:52 AM 7:06:59 AM 7:09:06 AM

Figure 69. Pre- and post-implosion data collected from Receiver Site 3 for the transmitters

located at Site D.
Figure 70. The stadium collapses during the implosion sequence.

82
-^'"

Jjgl-t"'; ;^-^

Figure 7 1 . Photos of stadium after the implosion.

83
Figure 72. Photos of stadium after the implosion.

84
(a)

(M| fl

{ I 1^ W> >"_ jj. T--gf I' r

(b)

^ !/"

(c)

Figure 73. Receiving sites before and after implosion (a) Site 1, (b) Site 2, and (c) Site 3.

85
Figure 74. Illustration of measurements with mobile cart.

86
-40

-50 —

49.78 MHz

162.20 MHz

226.50 MHz

448.80 MHz

902.45 MHz

1830.0 MHz

50 100 150 200 250 300 350 400 450 500 550 600 Data file location

Figure 75. Post-implosion mobile cart perimeter measurements for the transmitters at transmitter

Site A for horizontally polarized receiving antennas.

-

/ 49.66 MHz

-40 — 163.30 MHz

225.40 MHz

-50 —

1 . . 1

1

448.60 MHz

902.60 MHz

1831.00 MHz

\ J -60 —

E

CQo

r -70 —

O

a. -80 —

^

-

1 1 J iJ i

. U, 1

1 "1 iJilill tiiil Ikvuhi !

-100 —1

«

' 1' 1

'

1

' 1' 1

'

1

'

1

' 1'

1

'

1

' 1

'

1 50 100 150 200 250 300 350 400 450 500 550 600 Data file location

Figure 76. Post-implosion mobile cart perimeter measurements for the transmitters at transmitter

Site B for horizontally polarized receiving antennas.

87
49.72 MHz

165.54 MHz

226.40 MHz

448.70 MHz

50 100 150 200 250 300 350 400 450 500 550 600 Data file location

Figure 77. Post-implosion mobile cart perimeter measurements for the transmitters at transmitter

Site C for horizontally polarized receiving antennas.

-40

-50

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

50 100 150 200 250 300 350 400 450 500 550 600 Data file location

Figure 78. Post-implosion mobile cart perimeter measurements for the transmitters at transmitter

Site D for horizontally polarized receiving antennas.

88

1
-60

-70

->-49.60 MHz Site A PreBlast -^49.78 MHz Post - H 1 - Site A -»-49.78 MHz Post - H 2 - Site A ]

IV

i\ 1

l\

I 1

t

J h.sk ^\

Mmmtokk ' 1

"i^*! ** 1* L •- -XV wiWte i 1 1^ - s^

-90

-100 •^^*i45 90 135 180 225 Azimuth from Stadium Center (deg)

Figure 79. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 49 MHz band.

-50

-70

o -80

-90

-110

1 , ; 1 i 1-^49.60 MHz Site B PreBlast -»- 49.66 MHz Post - H 1 - Site B -*- 49.66 MHz Post - H 2 - Site B

I

t f

A,

\ I K Ui\ L

\ ^

W!umm4im( K \ JB.\

Kj

^ il y 1'

u 1 ^w*\5PK*^

^'kk>

1

45 135 180 225 Azimuth from Stadium Center (deg)

270 315 360

Figure 80. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site B for horizontally polarized receiving antennas: 49 MHz band.

89
135 180 225 Azimuth from Stadium Center (deg)

360

Figure 81 . Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site C for horizontally polarized receiving antennas: 49 MHz band.

-10 -^49.60 IVIHz Site D PreBlast -h^-49.6 MHz Post - H 1 - Site D -^49.6 IVIHz Post - H 2 - Site D | -20

-30

-40

m -50

-60 o

>

S -70

Of

-80

Qn

i

n Jh. i r^ \

y \

nlK^n \ /I

^ ^

V 1/

^'V

w f^.J\^

A * rt^ \a l\f,Y

-100

-110

.c#waIWM^(^^ ^U^S^kAXlAi^Wvi ' * w

135 180 225 Azimuth from Stadium Center (deg)270

Figure 82. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site D for horizontally polarized receiving antennas: 49 MHz band.

90
E -60

3o -70

1 1 1 1 !_•- 162.09 MHz Site A PreBlast -•-162.2 MHz Post -HI- Site A -*- 162.2 MHz Post - H 2 - Site A A

l\f\

1 K\\

m^\

A H 1 .At t \fA 1«A ,/j\ lb

|h w^fMWJ#f^^kfW IB^ iWfi

135 180 225 Azimuth from Stadium Center (deg)

Figure 83. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 160 MHz band.

135 180 225 Azimuth from Stadium Center (deg)

Figure 84. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site B for horizontally polarized receiving antennas: 160 MHz band.

91
-40

-50

-60

> -80

-90

-100

-110

-«-162.09 MHz Site C PreBlast -^165.54 MHz Post - H 1 - Site C -•-165.54 MHz Post - H 2 - Site C

rO

A \ n

1li k

l\J

m

f\i At

u

f

k \\

pm7V«\wp/jhfflpm^mn1^

45 90 135 180 225 Azimuth from Stadium Center (deg)

270 315 360

Figure 85. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site C for horizontally polarized receiving antennas: 160 MHz band.

-10

1 1 1 1 1 \ -•- 162.09 MHz Site D PreBlast -^162.09 MHzPost- H 1 -Site D -1-162.09 MHzPost- H 2-Site D

-20

-30

-40

m -50 n

/ N

1 . J o

S -70

0) rJi t

A \ y\

A

K, 1

K ^NM I

-90-

-100

-110

\m\} Af

V

* u

^4^^\ wvllLjftwwa b/ \ (1/ ^4^• A/^uiMNAl^

90 135 180 225 Azimuth from Stadium Center (deg)

270

Figure 86. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site D for horizontally polarized receiving antennas: 160 MHz band.

92
-30

-40

-50

F -60

ton

toS

„" -/O

-90 ,

1 1 1 1 i 1 -^225.30 MHz Site A PreBlast -^226.5 MHz Post - H 1 - Site A -*- 226.5 MHz Post - H 2 - Site A

_.L

J

4i)f^

/I

V yii|^

Am

liW^n^hIjf -%mv^ IP^-TT"

45 90 135 180 225 Azimuth from Stadium Center (deg)

270 315 360

Figure 87. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 225 MHz band.

45 90 135 180 225 Azimuth from Stadium Center (deg)

315 360

Figure 88. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site B for horizontally polarized receiving antennas: 225 MHz band.

93
-100

-110 135 180 225 Azimuth from Stadium Center (deg)

Figure 89. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site C for horizontally polarized receiving antennas: 225 MHz band.

-50

-60

S -70

-80

-100

-^225.30 MHz Site III D PreBlast -^225.3 MHz Post -HI- Site D -*- 225.3 MHz Post - H 2 - Site D |

1

1,

h

J

r \

lite( 'lA

A A w

i w\/ \/\ r .i \ ^. K , mMPi

V[Ma/Uj

V YlJl 'f^\ W\kiu

wvYH Wl^V

i

90 135 180 225 Azimuth from Stadium Center (deg)270 315

Figure 90. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site D for horizontally polarized receiving antennas: 225 MHz band.

94
-30

448.50 MHz Site A PreBlast -li- 448.8 MHz Post - H 1 - Site A -^448.8 MHz Post - H 2 - Site A

135 180 225 Azimuth from Stadium Center (deg)

Figure 91. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 450 MHz band.

90 135 180 225 Azimuth from Stadium Center (deg)

360

Figure 92. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site B for horizontally polarized receiving antennas: 450 MHz band.

95
1

:

i

! [--»- 448.50 MHz Site C PreBlasf -^448.7 MHz Post - H 1 - Site C ---448.7 MHz Post - H 2 - Site C

Hfv 1

fv

1

\ u A

\fi I-

» U/ ili % #3v,

VMWW^

i\ \

V»W' tilL i' [/^ 7 - LWJ|y^

45 90 135 180 225 Azimuth from Stadium Center (deg)270 315 360

Figure 93. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site C for horizontally polarized receiving antennas: 450 MHz band.

-30

-40

-50

E -60

„° -70

ff -80 -

-100

-^448.50 MHz Site D PreBlast -^448.5 MHz Post -HI- Site D ^>- 448.5 MHz Post - H 2

- Site D

(]

.A

1 :a /. 1

\

Fit

ilm^ M j\ \ t Att

/ Pvk '

\ 1t^lt \J Aft V Iai

fW^VTWXr

f

Shifi mfc\Ai^ ' i

45 135 180 225 Azimuth from Stadium Center (deg)

270 315

Figure 94. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site D for horizontally polarized receiving antennas: 450 MHz band.

96

I
> -80

-110 135 180 225 Azimuth from Stadium Center (deg)

360

Figure 95. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 900 MHz band.

45 90 135 180 225 Azimuth from Stadium Center (deg)

Figure 96. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site B for horizontally polarized receiving antennas: 900 MHz band.

97
135 180 225 Azimuth from Stadium Center (deg)

270 315 360

Figure 97. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 1800 MHz band.

-50

-60

-70

3

n° -80

-90

-100

-110

1830.0 MHz Site B PreBlast -^1831 MHz Post - H 1 - Site B -^1831 MHz Post - H 2 - Site B

135 180 225 Azimuth from Stadium Center (deg)360

Figure 98. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 1800 MHz band.

98
-40

-50 —

-60

0)o -80

Dl

-90

-100 —

-110

49.78 MHz

162.20 MHz

226.50 MHz

448.80 MHz

902.45 MHz

1830.0 MHz

vx^iffwrnw

'

I

'

I

'

I

'

I

'

I 'I

'

I 'I

'

!

' 20 40 60 80 100 120 140 160 180 200 Data file location

Figure 99. Post-implosion mobile cart perimeter measurements for the transmitters at transmitter

Site A for vertical polarized receiving antennas: perimeter walk 1.

-30

-40

-50 —

-60 Em

o

o

Q.

-70

-80

-90

-100

-110

49.66 MHz

163.30 MHz

225.40 MHz

448.60 MHz

902.60 MHz

^^ViM^^H'^i'i^^^

I

I

'

I

'

I

' I'

I

'

I

'

I

'

I

'

I

'

20 40 60 80 100 120 140 160 180 200 Data file location

Figure 100. Post-implosion mobile cart perimeter measurements for the transmitters at transmitter Site B for vertical polarized receiving antennas: perimeter walk 1.

99
-70

-80

E

CO

T3tr -90 o

-100

-110

49.72 MHz

165.54 MHz

226.40 MHz

448.70 MHz

'

I 'I '

I

' I

'

I 'I 'I

'

1

'

I

' 20 40 60 80 100 120 140 160 180 200 Data file location

Figure 101. Post-implosion mobile cart perimeter measurements for the transmitters at transmitter Site C for vertical polarized receiving antennas: perimeter walk 1.

-40

-50

-60

o -80

Q.

-90

-100

-110

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

'

I

'

I

'

I

'

I

'

I

'

I 'I

'

I ' I

' 20 40 60 80 100 120 140 160 180 200 Data file location

Figure 102. Post-implosion mobile cart perimeter measurements for the transmitters at transmitter Site D for vertical polarized receiving antennas: perimeter walk 1.

100
-40

-50

-60

o -80

Q.

-90

-100

-110

49.78 MHz

162.20 MHz

226.50 MHz

448.80 MHz

902.45 MHz

•jif'i^ rmj;^\P''fy>''^f\;:f:^,iV:\

1 I I

I

I II II

I

I

I r

20 40 60 80 100 120 140 160 180 200 220 240 Data file location

Figure 103. Post-implosion mobile cart perimeter measurements for the transmitters at transmitter Site A for vertical polarized receiving antennas: perimeter walk 2.

-30

-40 —

-50 —

-60 —

E

COD

tr -70

o

-80 —

-90

-100 —

-110

49.66 MHz

163.30 MHz

225.40 MHz

448.60 MHz

902.60 MHz

1831.00 MHz

i'i t"f'\i/|['''»^

n—I\—I—I—i\—\ \ \ r

"1

\—I—I

I

\

^

\ r

20 40 60 80 100 120 140 160 180 200 220 240 Data file location

Figure 104. Post-implosion mobile cart perimeter measurements for the transmitters at transmitter Site B for vertical polarized receiving antennas: perimeter walk 2.

101
-70

-80

E

COtr -90

CDo

Q.

-100 —

-110

49.72 MHz

165.54 MHz

226.40 MHz

448.70 MHz

"1

I

I

I r "1

I iI

I

I

I I r

20 40 60 80 100 120 140 160 180 200 220 240 Data file location

Figure 105. Post-implosion mobile cart perimeter measurements for the transmitters at transmitter Site C for vertical polarized receiving antennas: perimeter walk 2.

-40

-50

-60 —

o -80

CL

-90

-100

-110

49.60 MHz

162.09 MHz

225.30 MHz

448.50 MHz

'

I

'

I

'

I

'

I

'

I

'

I 'I

'

I 'I

'

I

' I

' 20 40 60 80 100 120 140 160 180 200 220 240 Data file location

Figure 106. Post-implosion mobile cart perimeter measurements for the transmitters at transmitter Site D for vertical polarized receiving antennas: perimeter walk 2.

102
-50

|-^49.60 MHz Site A PreBlast -^49.78 IVIHz Post - Vert 1 - Site A -*-49.78 MHz Post - Vert 2 - Site A |

Received

Power

(dBm)

D

CO

-^

CD

D

O

O

O n

I\

L

1 A

1m_ \l . 4 J

\ t \ j^ I .*

-100

-110

j/i%\Aiiwlm^1^

^w

H i(TM ••i» « ? ^ -i \[ V

45 90 135 180 225 Azimuth from Stadium Center (deg)

Figure 107. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 49 MHz band.

-50

-60

-70

«° -80

-100

'

i -^49.60 MHz Site B PreBlast -^49.66 MHz Post- Vert 1 - Site B -*- 49.66 MHz Post- Vert 2 -Site B

i

1

1

1

L. A

f MJ\ 1\ ,r^ ^ K .Vhl • '"i

fi iwf

i

Ty 1 "

' !

It - r

:

- lim 'J- -- ii

:

—- - Ml-*if -1 * m

45 90 135 180 225 Azimuth from Stadium Center (deg)

360

Figure 108. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site B for horizontally polarized receiving antennas: 49 MHz band.

103
-70

„° -80

-110

1 1 1 1 -49.60 MHz Site C PreBlast —-49.72 MHz Post -Vert1 -SiteC -^49.72 MHz Post -Vert 2 - SiteC

-

I J)1 A

! n ,-

1 .

t Li u 4 ,- «1 t ;\ ^

^

U 111 t i M JL V

4 K* * t n . i VV J h h A If\^

f?lw mmw

—

4mn

yi

*N r fypi

-90 r ^, -H-— ^

45 90 135 180 225 Azimuth from Stadium Center (deg)

270 315 360

Figure 109. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site C for horizontally polarized receiving antennas: 49 MHz band.

49.60 MHz Site D PreBlast -•-49.6 MHz Post - Vert 1 - Site D -*-49.6 MHz Post - Vert 2 - Site D

g -65

90 135 180 225 Azimuth from Center (deg)

360

Figure 1 10. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site D for horizontally polarized receiving antennas: 49 MHz band.

104
-30

-40

-50

I

-60

„° -70

-80

-90

-100

-^162.09 ['til MHz Site A PreBlast -^162.2 MHz Post - Vert 1 - Site A -*- 162.2 MHz Post - Vert 2 - Site A

' lA, l ._.._ ^ASVi h

' 7

1

Tn ' \

\ ^

f

' k

\ f ^^a^4^*^tvAf^m^ ' ihf^fj^^^^

!

1 i

1£ Azimuth from Center (deg)315 360

Figure 111. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 160 MHz band.

-25 1

162.09 MHz Site B PreBlast -*- 163.3 MHz Post - Vert 1 - Site B -*- 163.3 MHz Post - Vert 2 - Site B

-105 90 135 180 Azimuth from Center (deg)

225 360

Figure 1 12. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site B for horizontally polarized receiving antennas: 160 MHz band.

105
-45

5

„° -75

1 -^162.09 MHz Site CPreBlast -i^ 165.54 MHz Post- Vert 1 -SiteC ^^165.54 MHz Post -Vert 2 -Site C | |

n

I \f\

r

\

rJt -- K K i

\

ifi

^

r !

mAv!dij

\

Wv

i

f^iwi«ii>^ WC^/l- Y*^

^P^-rMMri

V ^[Wf- -^^y'T'r«^X^

-85

-95 ^?^7J135 180 225 Azimuth from Center (deg)

Figure 113. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site C for horizontally polarized receiving antennas: 160 MHz band.

-15

-105

162.09 MHz Site DPreBlast -^162.09 MHz Post -Vert 1 -SiteD -*- 162.09 MHz Post -Vert 2 -Site D

45 135 180 225 Azimuth from Center (deg)

360

Figure 114. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site D for horizontally polarized receiving antennas: 160 MHz band.

106
-25 1

-35

-45

I -55

CO

3

o -65

-85

-95

; !

; 1 i-^225.30MH2SiteAPreBlast -^226.5 MHz Post -Vert 1 -SiteA -•- 226.5 MHz Post - Vert 2 - Site A

\, jAil

/

i

ihy

/

ll\

I

.

/

r

\ . (44^1 r^l*^'^^**^•^ifUi^^ Y/T^vg^y "Wiw" V 1

-4LftJ K?^^^ Am* fsji 'jMfTOr"* CM^^w^

135 180 225 Azimuth from Center (deg)270 315 360

Figure 115. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 225 MHz band.

-25

225.30 MHz Site B PreBlast -ii- 225.4 MHz Post - Vert 1 - Site B -^225.4 MHz Post - Vert 2 - Site B

135 180 225 Azimuth from Center (deg)

Figure 116. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site B for horizontally polarized receiving antennas: 225 MHz band.

107
-25

-35

I -55

CQ

„° -65

-85

-105

1 [

i |-»-225.30 MHz Site CPreBlast —^226.4 MHz Post- Vert 1 - Site C -<- 226.4 MHz Post- Vert 2- Site C

1 i

Itlk

.

y

,

aLtojak^h^i^bk |sc^^A;/^/\i1U--^ i^Vi. m^V^l^if*^^ *r -* T i^ViP*V'->r'

45 90 135 180 225 Azimuth from Center (deg)

315 360

Figure 117. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site C for horizontally polarized receiving antennas: 225 MHz band.

-25

1 ! 1 1

1 i

1 -*- 225.30 MHz Site D PreBlast —-225.3 MHz Post - Vert 1 - Site D —^225.3 MHz Post - Vert 2 - Site D

-35

-45

1 -55

GO2,

° -65- a

>s

a>o yi75 -

ji

i

\ HIII

n khU/

r

• r\A

K

ffi

f N\N

-85 - M

m

fl 1 nI, A;n> '

I f^

ff %1W

-105

1

90 135 180 225 Azimuth from Center (deg)270 315

Figure 118. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site D for horizontally polarized receiving antennas: 225 MHz band.

I

108
-25

448.50 MHz Site A PreBlast -^448.8 MHz Post - Vert 1 - Site A -^448.8 MHz Post - Vert 2 - Site A

135 180 225 Azimuth from Center (deg)270 315 360

Figure 119. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 450 MHz band.

-35

E -55

5P -65

-95

-105

-^448.50 MHz Site'III B PreBlast -^448.6 MHz Post -Vert 1 - Site B -*-448.6 MHz Post -Vert 2 - Site B j

. \)\L AiHr^,

1'i f, f]f\Ml\\L

J A r^li

h

rfr

7 "1 V

\k i V I

' \A

k^W^"k^iCJSf^^

4/fl LI" :V,A/r^BLJlAUyT\ .j(/i ^ iMii^ V£>^^j*?^A;AUs^

Jr**v«*^^-r» » > •% - • • v^

90 135 180 225 Azimuth from Center (deg)

315 360

Figure 120. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site B for horizontally polarized receiving antennas: 450 MHz band.

109
-25

4£8.50 MHz Site C PreBlast -*- 448.7 MHz Post - Vert1 -SiteC-»- 448.7 MHz Post - Vert 2 - Site C |

90 135 180 225 Azimuth from Center (deg)270 315 360

Figure 121. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site C for horizontally polarized receiving antennas: 450 MHz band.

-25

-448.50 MHz Site D PreBlast -^448.5 MHz Post- Vert 1 -SiteD -*- 448.5 MHz Post- Vert 2 -Site D

90 135 180 225 Azimuth from Center (deg)

360

Figure 122. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site D for horizontally polarized receiving antennas: 450 MHz band.

110

J
135 180 225 Azimuth from Center (deg)

360

Figure 123. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 900 MHz band.

-25

-105

902.45 MHz Site B PreBlast -<- 902.6 MHz Post - Vert 1 - Site B -*- 902.6 MHz Post - Vert 2 - Site B

A^*^^^dK«HM^^|l4^^

45 90 135 180 225 Azimuth from Center (deg)

270 315 360

Figure 124. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site B for horizontally polarized receiving antennas: 900 MHz band.

Ill
-25 n

1

1 1

1 1i M

-^ 1 830.0 MHz Site A PreBlast -— 1 830 MHz Post - Vert 1 - Site A -*- 1 830 IVIHz Post - Vert 2 - Site A |

"^R -

e e:c . CQ2, A

1

u

S.5 7*^ - \A- -4- .\ \ \If '^ % ^kM A\

I mI^V/

iAj^u r MkA% ^y^jU/^8w^W"

-105 -

'

i? \ ~x\ ^

45 90 135 180 225 Azimuth from Center (deg)270 315 360

Figure 125. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site A for horizontally polarized receiving antennas: 1800 MHz band.

-25

1830.0 IVlHz Site B PreBlast -«- 1831 MHz Post - Vert 1 - Site B -*- 1831 MHz Post - Vert 2 - Site B

90 135 180 225 Azimuth from Center (deg)

360

Figure 126. Comparison of pre- and post-implosion mobile cart perimeter measurements for the

transmitters at transmitter Site B for horizontally polarized receiving antennas: 1800 MHz band.

112
(b)

Figure 127. Illustration of debris radiator measurements: (a) on Cable 1 on south side of stadium,

(b) on Cable 2 on north side of stadium.

113

NIST Technical Publications

Periodical

Journal of Research of the National Institute of Standards and Technology—Reports NIST research and

development in metrology and related fields of physical science, engineering, applied mathematics, statistics, biotechnology, and information technology. Papers cover a broad range of subjects, with major emphasis on

measurement methodology and the basic teclmology underlying standardization. Also included from time to time are survey articles on topics closely related to the Institute's technical and scientific programs. Issued six times a year.

Nonperiodicals

Monographs—Major contributions to the technical literature on various subjects related to the Institute's scientific and technical activities. Handbooks—Recommended codes of engineering and industrial practice (including safety codes) developed in cooperation with interested industries, professional organizations, and regulatory bodies. Special Publications^Include proceedings of conferences sponsored by NIST, NIST aimual reports, and other

special publications appropriate to this grouping such as wall charts, pocket cards, and bibliographies.

National Standard Reference Data Series—Provides quantitative data on the physical and chemical properties of

materials, compiled from the world's literature and critically evaluated. Developed under a worldwide program

coordinated by NIST under the authority of the National Standard Data Act (Public Law 90-396). NOTE: The

Journal of Physical and Chemical Reference Data (JPCRD) is published bimonthly for NIST by the American

Institute of Physics (ALP). Subscription orders and renewals are available from AIP, P.O. Box 503284, St. Louis,

MO 63150-3284.

Building Science Series—Disseminates technical information developed at the Institute on building materials,

components, systems, and whole structures. The series presents research results, test methods, and performance

criteria related to the structural and environmental functions and the durability and safety characteristics of building

elements and systems.

Technical Notes—Studies or reports which are complete in themselves but restrictive in their treatment of a subject.

Analogous to monographs but not so comprehensive in scope or definitive in treatment of the subject area. Often

serve as a vehicle for final reports of work performed at NIST under the sponsorship of other government agencies.

Voluntary Product Standards—Developed under procedures published by the Department of Commerce in Part

10, Title 15, of the Code of Federal Regulations. The standards establish nationally recognized requirements for products, and provide all concerned interests with a basis for common understanding of the characteristics of the products. NIST administers this program in support of the efforts of private-sector standardizing organizations.

Order the following NISTpublications—FIPS and NISTIRs—from the National Technical Information Service,

Springfield VA 22161.

Federal Information Processing Standards Publications (FIPS PUB)—Publications in this series collectively

constitute the Federal Information Processing Standards Register. The Register serves as the official source of

information in the Federal Government regarding standards issued by NIST pursuant to the Federal Property and

Administrative Services Act of 1949 as amended. Public Law 89-306 (79 Stat. 1 127), and as implemented by

Executive Order 11717 (38 FR 123 15, dated May 1 1,1973) and Part 6 of Title 15 CFR (Code of Federal

Regulations).

NIST Interagency or Internal Reports (NISTIR)—The series includes interim or final reports on work performed

by NIST for outside sponsors (both govermnent and nongovernment). In general, initial distribution is handled by

the sponsor; public distribution is handled by sales through the National Technical Information Service, Springfield,

VA 22161, in hard copy, electronic media, or microfiche form. NISTIRs may also report results of NIST projects of

transitory or limited interest, including those that will be published subsequently in more comprehensive form.
U.S. Department of Commerce

National Bureau of Standards and Technology

325 Broadway

Boulder, CO 80305-3328

Official Business

Penalty for Private Use $300