NAT'L INST. OF STAND & TECH R.I.C. tll«l||l»tl|.Wi'i?M.jV^'(llll}«V)

AlllDS fiT17S7

NISI

PUBLiCATIONsI

Nisr United States Department of Commerce

Technology Administration

National Institute of Standards and Technology

NIST Technical Note 1517

RF Material Characterization

Using a Large-Diameter

(76-8 mm) Coaxial Air Line

Chriss A. Jones

John H. Grosvenor

Claude M. Weil

QC

100

U5755

N0.1517

2000

NIST Technical Note 1517

RF Material Characterization Using a

Large-Diameter (76.8 mm) Coaxial Air Line

Chriss A. Jones

John H. Grosvenor

Claude M. Weil

Radio-Frequency Technology Division

Electronics and Electrical Engineering Laboratory

National Institute of Standards and Technology

325 Broadway

Boulder, Colorado 80303-3328

February 2000

'"TES

U.S. DEPARTMENT OF COMMERCE, William M. Daley, Secretary

TECHNOLOGY ADMINISTRATION, Dr. Cheryl L. Shavers, Under Secretary of Commerce for Technology

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, Raymond G. Kammer, Director
National Institute of Standards and Technology Technical Note

Natl. Inst. Stand. Technol., Tech. Note 1517, 56 pages (Feb. 2000)

CODEN:NTNOEF

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 2000

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402-9325
TABLE OF CONTENTS

PAGE

1. INTRODUCTION 1

1 . 1 Methods of Reducing Air-Gap Errors 2

2. EXPERIMENTAL METHODOLOGY 5 2 .

1

Coaxial Air Line Hardware 5 2.2 Calibration Techniques 5

2.3 Material Characterization Measurements 10

3. EXPERIMENTAL RESULTS 11

3.1 Early Measurements 11

3.2 Improved Characterization Measurements 13

4. DISCUSSION AND CONCLUSIONS 22

REFERENCES 23

APPENDIX A. Machine Drawings of Coaxial Line System Hardware 25

APPENDIX B. Listing for External OSLT Calibration Program 33

111

RF Material Characterization Using a Large-Diameter

(76.8 mm) Coaxial Air Line

Chriss A. Jones, John H. Grosvenor, and Claude M. Weil

Radio-Frequency Technology Division

Electronics and Electrical Engineering Laboratory

National Institute of Standards and Technology

Boulder, Colorado 80303-3328

We report on the development of a 76.84 mm (3.025 in) diameter coaxial air line

system whose purpose is to measure the dielectric and magnetic properties of bulk

dielectric and ferrite materials over a frequency range of approximately 0.3 MHz to 2000 MHz. We summarize the relative advantages and disadvantages of using largediameter coaxial air lines for material characterization, and we discuss the particular

problems associated with calibrating vector network analyzers in this form of

transmission line. We also present broadband measurement data for low-loss polymer

and ceramic dielectrics as well as for lossy materials that included a ferrite-loaded

polymer and carbon-loaded concrete.

Keywords: coaxial air line; dielectrics; ferrites; loss tangent; materials; measurements;

permittivity; permeability; radio-frequency.

1. INTRODUCTION

The transmission/reflection (T/R) method in coaxial air lines is a widely used broadband technique

for measuring the dielectric and magnetic properties of certain bulk materials at radio/microwave

frequencies. It has recently been documented as a standardized measurement method by ASTM [1].

In this method, a toroidal sample of the material under test is precisely machined to the air-line

dimensions and positioned inside the line. Two-port scattering (S-)parameters, both reflected and

transmitted, are then measured over a broad frequency range, usually by means of an automatic

vector network analyzer (VNA). Data on the complex dielectric permittivity, e* = e/ -Je," and

complex magnetic permeability, ///= /j/ - jju/' are derived from the measured S-parameter data

using various available reduction algorithms [2-5]. Coaxial air lines of 7 mm outer diameter are

generally used for this purpose because they nominally cover a broad frequency range of GHz to 18 GHz, and because they are readily available from commercial sources.
The broadband transmission-line measurement techniques suffer from two principal disadvantages.

The first is that they cannot satisfactorily measure the dielectric or magnetic loss of low-loss materials

(i.e., e^ '\ jj.^ "< 0.05) due to the low-Q characteristics of transmission-line structures and resulting

insensitivity for loss measurements. Such methods work satisfactorily when measuring the complex

permittivity and permeability of medium- to high-loss materials. Transmission-line techniques

generally suffice for measuring the real part e^ 'and pi^ 'only of low-loss materials, in cases where loss

data are not needed.

Any transmission-line or resonator technique, that involves placement of a material specimen under

test in very close proximity to metal conductors, is prone to serious air-gap errors caused by field

depolarization. Such errors constitute the technique's second major disadvantage. Air-gap effects occur whenever a normal component of the E- or H-field exists at the air-material interface. Since

the normal component of electric or magnetic flux density must be continuous at the air-material

interface, a discontinuity in the normal E- or H-fields results owing to the differences in e and yt* for

the material and air. The resulting depolarization error always causes measured permittivity or permeability data to be biased lower than actual values. For the coaxial air line operated in the

fundamental transverse electromagnetic (TEM) mode, normal electric field and tangential magnetic

components exist at the air-material interfaces. As a result, electric- but not magnetic-field

depolarization occurs at the interfaces. This means that the technique is very prone to air-gap errors when used to measure dielectric permittivity, but much less so for magnetic permeability. The 7 mm

coaxial air line method has been shown to be generally accurate to within better than ±2 % in //^ ' and

±0.01 in/^^ "when measuring the complex permeability of lossy polycrystalline ferrites at frequencies

below their gyromagnetic resonance [5,6].

1.1 Methods of Reducing Air-Gap Errors

There exist five principal methods for reducing and correcting air-gap errors when performing T/R

measurements of material permittivity. These can be used separately or in combination with each

other [5,7]:

1. Copper electroplating of the curved surfaces of the toroidal specimen.

2. Split "clam shell" coaxial air line holder to ensure improved contact with specimen

under test.

3. Application of conductive fillers such as pastes, solders, etc. in the air-gap region.

4. Correcfion using theoretical models, this requires an accurate knowledge of the air- gap dimension.

5. Use of coaxial air lines of larger diameter .
Each one of these approaches has its advantages and disadvantages. Not all materials can be

electroplated and good electrical contact between plated specimens and conductor walls is still essential. Excessive pressure applied to fragile specimens in the "clam shell" holder can easily fracture

them. Use of conductive fillers will bias loss-factor data upwards when measuring lower-loss

materials because the fillers are themselves very lossy. Error correction using theoretical models

works well provided that the inner and outer air-gap dimensions have been accurately estimated. Best

accuracy requires use of coordinate-measuring or air-gauge instrumentation. This is the approach

favored by NIST. The air-gap correction used by NIST is based on a simple concentric capacitor

model and is included in our iterative-based EPS_MU3 transmission-line software [5]. Because

uncertainties remain in the dimensional metrology process, NIST does not guarantee accuracies of

better than £/ = ±5 % for materials with £/ < 10 during T/R dielectric measurements performed in

7 mm coaxial air lines. These accuracies degrade rapidly for materials of e/ >10.

This publication deals with the fifth option listed above for reducing air-gap errors: use of largerdiameter coaxial airlines. Figure 1 shows a cross-sectional representation of the dielectric specimen

symmetrically mounted in a coaxial air line, plus uniform concentric air gaps between the specimen

and the inner and outer conductors.

Figure 1. Cross-sectional representation of coaxial air line containing dielectric specimen with uniform

and concentric air gaps.
Using a simple coaxial capacitor model [5, pp. 101-103] which employs three capacitors in series to represent the dielectric media and the two air gaps, we can readily derive values for observed or measured real permittivity e^ 'in terms of the actual or nominal 6 'of the material under test, given

the dimensions Dj , D2 , D^ , D^ . In Table 1, values of £„ 'have been derived for measurements of

materials with nominal 6 'values of 10, 100, and 1000 in different-sized 50 Q coaxial air lines with

D^/ Dj ^ 2.3 and a uniform air-gap width of 0.0254 mm (1 mil) throughout.

From the data of Table 1, we see that large differences exist between €^ 'and e'and that this error becomes significantly reduced as the diameter of the coaxial air line increases. For example, the error for a measurement performed on the £'= 100 material in the 7 mm diameter air line is -59 %,

whereas that for the 76.8 mm diameter line is only -11.2 %. Physically, this difference can be

explained by the reduced capacitance across the air gap existing in air lines of larger diameter caused

by the increase in surface area. The significant improvement in measurement accuracy realized

through use of larger diameter air lines is gained at the expense of reduced frequency coverage and

much-increased specimen volume needed for the material under test. However, machining tolerances

for the larger-sized specimens can be relaxed. The frequency coverage of the coaxial line is dictated

by the frequency where the first higher-order TEu mode will start to propagate within the dielectric

under test and depends on the line's diameter and the material's real permittivity. For example,

assuming a nominal e ' value of 4 for the material under test, the upper frequency limit for

measurements performed in a 7 mm line is approximately 19 GHz, that for the 14 mm line is approximately 9.5 GHz, and that for the 76.8 mm line is only about 1.73 GHz. However, for many

materials such as high-loss ferrites, only the low-frequency properties are of interest. Therefore, the

larger diameter coaxial air lines are well suited to cases where broadband measurements are needed

only for a frequency range below about 1000 MHz. Consequently, this report will emphasize

measurements at lower radio frequencies covering almost a four-decade range of 300 kHz to 2000

MHz

TABLE 1: Values of measured real permittivity ej iox materials of three different nominal

permittivities, as measured in 50 Q coaxial air lines of varying outer diameter; air gap = 0.025 mm.

A (mm) fj/

£'=10 6'= 100 £'=1000

41.2 67.1

58.4 122

71.5 199

80.5 291

88.8 441

7 8.85

14 9.39

25.4(1 in) 9.65

41.3 (l%in) 9.78

76.8 (3 in) 9.88
The authors are aware that large-diameter coaxial air line systems are being routinely used for

characterizing materials in industrial and academic measurement laboratories. However, few details

ofthese systems appear to have been published, other than a report on the broadband characterization

of Portland cement concrete, using a 150 mm diameter coaxial air line [8].

2. EXPERIMENTAL METHODOLOGY

2.1 Coaxial Air Line Hardware

We elected to construct our system using 76.8 mm (3.025 in) diameter coaxial components because

some ofthese are commercially available for high-power applications [9] and because NIST had on

hand two double-sectioned 50 Q tapered reducers of total length 435 mm, which transition from the

76.8 mm diameter coaxial air line down to a 14 mm coaxial connector. However, many additional

components were needed, which were designed and fabricated in our in-house machine-shop facilities. These included two 150 mm long coaxial extenders (mode filters) which are permanently attached

to the adapters (the reason why the extenders are needed is discussed in Section 3) plus a 102 mm

(4 in) long coaxial air line section in which the specimens under test are mounted (see Figure Al).

The air line and extender sections were fabricated using 76.8 mm ID and 33.4 mm CD copper tubing

of 1 mm wall thickness. Copper flanges, 133 mm in diameter and 6.3 mm thick, were soldered onto

the outer conductor tube at both ends ofthe air line section (Figure A2). Figure 2 shows the tapered

transition assembly with extender section attached. The center conductor is held in place using three

polytetrafluoroethylene (PTFE) posts spaced 120° apart and the center conductors of the transition

and extender sections are permanently connected using a connection bullet and small machine screws. To connect sections of the outer conductor together, the flanges are aligned with each other using

two 6.3 mm pins and fastened together using six nominally 1.5 in long %-20 machine screws and

nuts. Center conductors were connected using a unique stainless steel male bullet containing slotted

flowers at both ends, which is partially inserted inside the center conductor tubing (see Figure A3).

In the photograph of Figure 3, the 102 mm coaxial air-line section is shown on the right with a

material specimen partially inserted inside it and a connection bullet mounted in the center conductor.

Additional components were needed to calibrate the VNA in this transmission line system (see

Section 2.1 below), including 175 and 203 mm long air-line sections, two shorting plates with half- bullets attached (see Figure A4), plus two 50 Q loads with transitions, which were procured from

a commercial source [9]. Figure 4 illustrates the calibration components together with some of the

connection bullets. The fiilly assembled transmission line system is illustrated in figure 5.

2.2 Calibration Techniques

Use of a VNA to perform two-port S-parameter measurements, requires that the instrument be first calibrated in the transmission-line system being used; i.e., in our case, in the 76.8 mm coaxial air line system. This process is required in order to correct for the imperfections and systematic errors

inherent in the VNA system including impedance mismatches, RF leakage, and the finite directivity

and bandwidth of the instrument's reflectometer couplers, etc. Calibration is achieved by measuring
14 mm

connector

3 dielectric post

supports)^

50 Q

tapered

reducers

3 dielectric post \

supports

I

15 cm

airline (mode filter)

Figure 2. Tapered reducer assembly with 150 mm extender section.

Figure 3. 102 mm long specimen holder section, showing alumina specimen partially inserted (on

right). A standard 7 mm diameter coaxial air line, with specimen, is shown on left.
Figure 4. Calibration and other components; the 200 mm line is shown at top, the specimen holder

at top right, the tapered load at right center and a shorting plate at bottom left The long line diagonally positioned in the center was later cut in two and used for the mode-filter extenders.
Figure 5. Fully assembled transmission-line system

the S-parameters of a set of known impedance standards, such as a "Short" (or "Reflect"), an "Open", a matched "Load", a "Thru" or a known length of transmission "Line". A set of 12 error correction coefficients are then derived in the VNA's internal firmware by solving a set of 12

simultaneous equations that describe the reflectometer system using a flow-diagram representation

[10]. The performance of the standards is typically described by a lumped-element equivalent circuit,

termed the "Calibration Kit Parameters" by the instrument manufacturer. The correction coefficients are subsequently applied to the S-parameter measurements, thereby yielding fully corrected data.

Over the years, many different types of calibration techniques have been developed. One of the most

widely used and accurate techniques is the "Thru-Reflect-Line" (TRL) method [10]. A capability for

processing the TRL calibration data is usually provided in the VNA instrument's firmware. A TRL

calibration involves three different connection configurations, which are illustrated in figure 6 for our

large-diameter coaxial system. In the first "Thru" configuration, the two reference planes at the ends

of the extender sections are fastened together to form a through connection. In the second "Reflect"

configuration, both reference planes are terminated by shorting plates, while in the third "Line"

configuration, another section of transmission line of the same characteristic impedance is connected

between the reference planes. The length of transmission line / required for the "Line" configuration

is computed using the following relationship:
^jedmen inside

Thru

Reflect

Siort

vdrcLMt standards

Line

Figure 6. Connection configurations for TRL calibration (reproduced from Reference [8], with

permission from Elsevier Science).

2n

(1)

where 4> is the desired phase delay of the line and A^ is the guide wavelength for the transmission line

used (identical to the free-space wavelength A^ in a lossless coaxial line). The value of / is normally

chosen to give a minimum phase delay of 20° at the lowest measurement frequency and a phase delay

of 160° or more at the highest frequency of interest [11]. We used the 203 mm long line section for

performing TRL calibrations in this transmission line system. Using eq (1), the minimal 20° phase

shift is obtained at approximately 82 MHz for this line length, which gives an approximate lowerfrequency limit for which a TRL calibration is valid. Hence, measurements based on TRL calibrations are generally limited to a frequency range of 45 MHz to approximately 1500 MHz, depending on the

dielectric material under test.

Because we were particularly interested in obtaining material characterization data at frequencies
below 45 MHz, we needed to use another form of calibration that is valid at these lower frequencies.

The "Open-Short-Load-Thru" (OSLT) technique is capable, in theory, of providing accurate

calibrations at frequencies down to the kilohertz range, because it does not involve trying to measure

small phase delays for a "Line" measurement. In the OSLT method, each end of the extender section

is initially terminated in a shielded open, where the line's outer conductor continues beyond the end

of the center conductor. In our system, a shielded open was realized by connecting only the outer

shield of an air-line section to the extender section. In the second step, the extender sections are terminated by shorting plates at the reference planes. In the third step, the tapered loads are connected

at the reference planes. The final step involves a "thru" measurement in which the reference planes

are connected together.

The OSLT technique is also supported by internal firmware in the VNA instrument and is usually

referred to as a "full two-port calibration" by instrument manufacturers [10]. The physical

characteristics of the three standards used in the OSLT method, based on approximate equivalent

circuit parameters, are stored in this firmware. The effective capacitance C^^ of the shielded open is generally described by a polynomial fianction in frequency/:

Ceff-C, ^CJ-C,f ^C,f , (2)

where Cq , C, , C2 , Cj are capacitive fitting coefficients derived from a full-field solution of the

shielded open problem [12]. Similarly, the effective inductance Z^^ of the coaxial short is described

by an identical polynomial containing inductive fitting coefficients Lq , Lj , L2 , L^ . For the 0.3 MHz

to 6000 MHz VNA instrument used for these measurements, estimates are provided in the internal

firmware of the effective capacitance for the open standard used during OSLT calibration in both 7

mm and 14 mm diameter coaxial air lines. However, there are no provisions in the firmware for

caHbrating the instrument in coaxial air-line systems of larger diameter. Because of this, we had to develop our own external calibration program in order to perform OSLT calibrations in the 76.8 mm

diameter coaxial air-line system. This included an estimate we derived for the effective capacitance

of the shielded open standard, using some theory and software developed earlier on another project

involving permittivity measurements of solids and fluids in a coaxial shielded open-circuit

configuration [13]. The external calibration program was written in HP BASIC and is listed in

Appendix B.

2.3 Material Characterization Measurements

2.3.1 Materials Tested

In order to validate our measurement system and determine its accuracy, we prepared specimens of

four different materials, whose dielectric/magnetic properties had been measured at NIST by other

techniques of equal or better accuracy. The specimens were prepared according to the specifications

given in Figure A5 to fit precisely inside the sample holder. The specimen thickness, / was arbitrary

and varied over a range of approximately 13 mm to 20 mm. These materials are listed below, together

10
with their nominal dielectric and magnetic properties at 100 MHz.

1. Cross-linked polystyrene (CLP), e'=2.55

2. Debased alumina ceramic,* e'=8.85

3. Calcium-strontium-titanate (C ST) ceramic, 6'= 275

4. Ferrite-loaded polymer (FLP), 6'= 16.1, /^'=4.5

* 88 % alumina with additions of SiOj , MgO, CrOzand CaO; porosity 2 % to 3 %

In June 1997, we were approached by a NIST customer with a request to characterize some samples

of carbon-loaded concrete at low frequencies (0.3 MHz to 50 MHz). This is a commercially made

material used to attenuate ground currents in power line and broadcast installations. Since this

material is known to be very lossy, it is well suited to T/R measurements in a transmission line. However, concrete often contains aggregate components of significant size ( > 1 mm). Consequently,

it is difficult to accurately machine small samples of this material that can be inserted into, for

example, a 7 mm coaxial air line. Because the customer was primarily interested in measurements at low frequencies and not in the microwave region, our 76.8 mm diameter coaxial air-line system

represented an ideal match to this requirement. The customer provided us with four samples, that had

been machined according to Figure A5, and we labeled them CLCl, CLC2, CLC3, and CLC4.

2.3.2 Measurement Methodology

Material characterization measurements were performed in the manner usually followed for T/R

transmission-line measurements. Two-port S-parameter data were measured by a VNA, following

system calibration, and the data subsequently processed using our EPS_MU_3 data reduction

algorithm [5]. This algorithm originally contained provisions for correcting the measured data for the

inevitable presence of air gaps in 7- and 14-mm diameter coaxial sample holders and was later modified to perform the same correction in our 76.8-mm diameter geometry. Most of the

measurements performed during the three-year time period during which this development effort took

place (1991-1994), were restricted to the frequency range of approximately 45 MHz to 2000 MHz,

because only a higher-frequency VNA was available to us. Regrettably, the Project's only lowfi"equency VNA was fully dedicated to other higher-priority tasks, so that we were unable to perform

measurements at frequencies below 45 MHz at this time.

Three years later, the Project had acquired a second low-fi^equency VNA, so that we were able to characterize the carbon-loaded concrete samples over a fiiU 0.3 MHz to 2000 MHz frequency range.

We used both the internal TRL and the external OSLT calibration program for these measurements.

The customer also asked us to repeat our measurement of specimen CLC3 one week after the original

, measurement.

11
3. EXPERIMENTAL RESULTS

3.1 Early Measurements

Following initial fabrication of the various hardware components and calibration standards, we sought

to verify the performance of the standards over the frequency range 45 MHz to 1000 MHz by

measuring the magnitude of S^ and S22 for the short, load and the 102 mm line standards. These data

were all within acceptable limits; |Sii| and IS22I for the load standards were about -30 dB.

However, when we measured the phase of S12 and Sji for the line standard, we noted a serious

anomaly. Figure 7 shows that the phase of S21, which should not normally change by more than a few

millidegrees with frequency, varied by +0.7° to - 1.5° relative to the 0° reference at frequencies above

about 585 MHz.

We subsequently attempted to measure the dielectric properties ofthe CLP sample over the frequency

range 45 MHz to 2000 MHz, following a TRL calibration of the system. The measured e'data for

CLP, which are shown in Figure 8, should be compared with a well-established reference value of e

= 2.55 ± 0.013 over this frequency range [14]. We see that good agreement is evident at frequencies

below about 500 MHz, but that significant deviations occur above this frequency. It is apparent that

the TRL calibration was unsatisfactory above 600 MHz owing to the significant phase deviations

shown in Figure 7, and that this leads, in turn, to the poor data of Figure 8. Upon further

investigation, we concluded that this problem was caused by the presence of higher-order

transmission-line modes that are incident on the specimen. Such modes are generated in the tapered

'21

1 P

h

a

se

1 (Deg.)

hp S21

REF 0.e "

/l PQR T 1

38.

EXTI

705

:nsi

ps

ON 1V

50G

-12.3

.0 m"

6 m"

/

101. 54 mm

^^^ y \

\

\ r

\^ 1

0.5 Frequency, GHz

Figure 7: Plot of S21 phase versus frequency for the 102 mm line standard.

12
a

LU

2.8

2.6 -

2.4

2.2 -

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Frequency, GHz

Figure 8. Early Measured Real Permittivity Data for Cross-Linked Polystyrene, following TRL

Calibration

adapter sections and are not sufficiently attenuated in the relatively short length (102 mm) of air line

used to hold the specimen. The solution for this problem was to design and fabricate the two 150 mm

long extenders which are permanently attached to the adapters. These sections ensure that any higherorder modes are completely attenuated before reaching the specimen under test.

3.2 Improved Characterization Measurements

3.2.1 Higher-Frequency Measurements Using Internal TRL Calibration

We repeated characterization measurements for the CLP sample, after installation of the extender

sections. The repeat data (see Figure 9) now exhibit a constant value e' = 2.55 at frequencies up to 1400 MHz. The instability evident at about 1475 MHz represents a measurement artifact

caused by an unwanted half-wavelength resonance within the 102 mm long specimen holder section

ofthe transmission-line system. Figure 10 shows similar data for the debased alumina sample. The

measured value of 6'= 9. 1 is constant up to about 800 MHz. Compare this with a reference value

of 6^= 8.85 ± 0.3 as measured by both NIST in a 14 mm diameter air line and by the University of

Nottingham, UK [15]. The somewhat higher value measured here is likely due to over-correction for

the air gap error, but is still within the uncertainty bounds of the reference data. The instability seen

13
i

-

-

,„ ^

"V^ ..--^ r^

' "A

• V

-

-

-

1

1 1 1 J 1 i 1 1 1 1 1 1 1 J r 1 1 1 1 1 1 1 1 1

1

2.8

2.7

2.6

"vu 2.5

2.4

2.3

2.2

2.1

2

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Frequency (GHz) no gap correction

Figure 9: Measured Real Permittivity Data for Cross-Linked Polystyrene, following TRL Calibration,

and using extender sections.

12

11.5

11

CO 10.5

10

> 9.5

u

Ph 8.5

P^

7.5

6.5

: With Gap Correction

1 1

]

•

\

;^ , 4—^-^4 > -^ ^J .. w^^^

: f

^

-^ ^Sr^

:

\

\

0.2 0.4 0.6 0.8 1 1.2 1.4 Frequency (GHz)1.6 1.8

Figure 10: Measured Real Permittivity Data for Debased Alumina, following TRL Calibration.

14
in the data ofFigure 10 at 1 150 MHz is probably due to propagation of the first higher-order mode

in the sample. This is a common problem that frequently occurs when performing T/R measurements

of low-loss dielectrics with £' values of 10 or more. The system artifact at 1475 MHz is again

evident in Figure 10.

Past attempts to characterize very high-permittivity and low-loss ceramics in 7 and 14 mm diameter

coaxial air lines had been unsuccessful owing to a number of problems. These included an inability

of the EPS_MU_3 algorithm to converge on the correct solution, as well as the very large air-gap

error that resulted. Consequently, we sought to determine whether a meaningful measurement of this

type of material could be realized using this system. Figure 1 1 shows measured e'data for a sample

ofcalcium-strontium-titanate (CST), both without and with air-gap correction. The corrected values

at fi^equencies below about 250 MHz are seen to compare well with the nominal value of £'= 275,

provided by the manufacturer. At higher frequencies, the data are clearly not reliable due to the

presence of many higher-order modes within the specimen, which occur at much lower frequencies

than usual owing to the very high permittivity of this material.

500

450

400

350

"vu 300

250

200

150

100

measurement using gap correction

measurement witliout gap correction

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Frequency (GHz)

Figure 11. Measured real permittivity data for calcium-strontium-titanate, following TRL Calibration.

15
We also measured the dielectric loss £"for the CLP, alumina and CST samples, but these data are not included here because they are not meaningful. As discussed earlier, the sensitivity limit for

measuring loss factor in any transmission line system is approximately tan 5= e'l€'= 0.01 and all three materials exhibit loss factor values that are at least ten times less. A final measurement in this series involved a ferrite-loaded polymer with medium dielectric and

magnetic loss. Figures 12 and 13 show the measured dielectric and magnetic properties, respectively.

The solid line represents data measured in this system, while the dotted lines represent reference data

obtained in a 7 mm coaxial air line measurement of this material [6]. Uncertainty bounds of ±2.5 %

for the 6

reference data and ±1.5% for the // ' reference data are included in Figures 1 2 and 1 3 . The

uncertainty bounds for the e "and }x "reference data are ±0.01. In Figure 12a, note that the measured

data for e"'lie within the uncertainty limits of the reference data, whereas the agreement for e "(see

Figure 12b) is clearly not good, particularly at frequencies above 900 MHz. In Figure 13, the

agreement with reference data is seen to be excellent for both real and imaginary parts.

3.2.2 Verification of External OSLT Calibration Program

After completing the external OSLT calibration program, we needed to verify that it was providing

satisfactory measurement data. We compared dielectric characterization data of air, CLP, and fusedsilica glass as measured in a 7 mm diameter coaxial air line system that had been calibrated using

either the VNA's internal full two-port calibration program or the external OSLT calibration

program; the effective capacitance of the 7 mm shielded open standard was separately estimated by

the external program. Data taken for the flised-silica glass are shown in Figure 14. These data were

not corrected for air-gap errors and are therefore somewhat lower than the accepted reference value

of 6'= 3.85 ± 0.02 at 5 GHz [14]. We see that there is very close agreement between the 6'data

obtained following the two different methods of calibration up to about 1 GHz. At frequencies above

this, the data obtained using the external calibration program appear increasingly unstable, and the

agreement deteriorates to a maximum of about 2.4 % near 2 GHz. The good agreement seen at lower

frequencies gave us confidence in the validity of the external calibration routine at frequencies below

45 MHz, but we were unable to actually verify this due to the instrumentation availability problems

discussed in Section 2.3. We subsequently performed a 45 MHz to 1000 MHz measurement on CLP

in our 76.8 mm coaxial air line system, following external OSLT calibration. We compared these data

with similar data obtained earlier in this system, following internal TRL calibration (see Figure 15).

As was seen in Figure 9, the data obtained following internal TRL calibration are flat with frequency

and compare well with a reference value of e'= 2.54. In contrast, the data obtained following

external OSLT calibration are seen to be unstable and vary by approximately ±3 %, relative to the

TRL data.

16
u

16.6

16.4

16.2

16

S 15.8 ^ 15.6

Q.

15 15.4

"^15.2

15

14.8

: Measured Data „

Reference

Ref. Uncertainty _

:

.,

\

\

'•..^

S >

^ **-

'*'*..,

: \ *- -**-^ * • ^

:

*'••..

: -—.. X

200 400 600 800 1000

Frequency, MHz

1200 1400

Figure 12a. Comparison of measured real permittivity data with reference data for the ferrite loaded

polymer.

0.6

0.55

0.5

CO-0.45

(0w

5 0.4

o

•£ 0.35

o

o

o 0.3

Q

0.25

0.2

0.15

"

/-—V Measured

: Reference

/

-AV/A

' /

; \/ — . --...

.„

: '••

*^

; *^

1 1 1 1 200 400 600 800 1000

Frequency, MHz

1200 1400

Figure 12b. Comparison of measured dielectric loss data with reference data for the ferrite loaded

polymer.

17
5

4.5

*i 4E

(0 3

Q)

t- 2.5

0)

o

g.1.5

o

O 1

0.5

:

h—1_- -"*-••-

^ i-i' t---^""-—^^-- S3^

'_

': Measured

Reference

Data

Ref. Uncertainty

\

': —

': til-

^

--''''^

—^^^^^^^^ 200 400 600 800 1000

Frequency, MHz

1200 1400

Figure 13. Comparison of measured complex permeability data with reference data for the ferrite- loaded polymer.

ohpcal-glass

-a- external cal-glass

<u

3.84

3.82

3.8

3.78

3.76

3.74

3.72

O "7 I I I I I • I I I I I ' ' ' ' I ' ' ' I I I ' '

' I ' I ' I I I ' 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Frequency (GHz)

Figure 14. Comparison of 6 'data for fused silica glass measured in a 7 mm coaxial air line following

internal and external OSLT calibration.

18
0.1 0.2 0.3 0.4 0.5 0.6 0.7

Frequency, GHz

Figure 15. Comparison of £ 'data for CLP measured in the 76.8 mm coaxial air line following internal

TRL and external OSLT calibration.

3.2.3 Low-Frequency Measurements of Carbon-Loaded Concrete.

Permittivity data, including loss factor, for the four carbon-loaded samples CLCl, CLC2, CLC3, and

CLC4 are given in Figure 16 over the frequency range 0.3 MHz to 50 MHz. Wide variations in dielectric properties are evident between the four samples. The differences between specimens were

not disclosed to us but are likely due to differences in carbon content as well as differences in curing

time for each specimen. Measured data were not included in Figure 16 for samples CLC2 and CLC3

below 5 MHz, nor for CLC4 below 20 MHz, because these data became increasingly unreliable at low frequencies. Similarly, the measured 6 'data for specimen CLC4 appeared to be inconsistent with

the other data and have not been included in Figure 16a. Most of the measured data at higher

frequencies above 100 MHz were very unstable and have generally not been included. However, the

higher-frequency data for Specimen CLCl are shown in Figure 16d which shows £ 'data as a function

of frequency over parts of four decades, 0.3-500 MHz. The unstable nature of the measurement at frequencies above 100 MHz is clearly evident in Figure 16d.

Figure 16e compares the loss factor data for Specimen CLC3 at the time of initial measurement and

after a fijrther week of curing time. The decrease seen in loss factor with increased curing time agrees

closely with the results of Al-Qadi et al. [8].

19
10

180

160

140

> 120

'BE1- 100

0) Q.

0)> 80

*j

ra

0) 60

a: 40

20

10 15 20 25 30 35 40 45 50

Frequency, MHz

Figure 16a; Relative Permittivity Data for the Carbon-Loaded Concrete.

1000

5 10 15 20 25 30 35 40 45 50

Frequency, MHz

Figure 16b: Dielectric Loss Data for the Carbon-Loaded Concrete.

20
to

(0

o

U.

W

0)O

Frequency, MHz

Figure 16c: Loss Factor Data for the Carbon-Loaded Concrete

80

75

70

'co 65

3?

>

60

ti 55

E

50

Q.

o 45

>

4-> (0 40

(D a: 35

30

25

\V

\

; \ CLC1

':

': ^ ': \ ':

\

; \^

^^'^wyw.

.

0.1 1 10 100 1000

Frequency, MHz

Figure 16d: Relative Permittivity Data for Specimen CLCl over an Extended Frequency Range

21
10

to

c

^-i 1 o

n

u.o

:

\

CLC:\

\ Initia 1 Meas urement

-

---. —..

^^ --

One Weel ( later

1 1 1 J 0.1

10 20 30 40 50 60 70 80 90 100

Frequency, MHz

Figure 16e. Change of loss factor with curing time for specimen CLC3.

No comparison data for this material were available to us so that we cannot draw any conclusions

regarding the validity or accuracy of these data. However, they are consistent with measurements

performed at NIST on other carbon-loaded materials such as the carbon-loaded urethane foam used

in anechoic chambers.

4. DISCUSSION AND CONCLUSIONS

We conclude that the measurements performed above 50 MHz following TRL calibration were

generally satisfactory, provided that the extender sections were used. In particular, measured 6 'data

for high- and very high-permittivity ceramics appeared to be more stable and accurate than

corresponding data obtained in a 7 mm or 14 mm coaxial air line measurement. Air-gap errors still needed to be corrected for, but the relative correction was much smaller, compared to that for the

smaller diameter air lines. The complex permeability data measured on the ferrite-loaded polymer

agreed very closely indeed with reference data, further demonstrating that the coaxial air line method

is one of the most accurate available for measuring the magnetic properties of demagnetized ferrites

at RF frequencies below gyromagnetic resonance.

Although the performance of the external OSLT program was never verified at frequencies below 50

MHz, the measurements performed on the carbon-loaded concrete appear to demonstrate that it generated satisfactory data for frequencies in the range 5 MHz to 100 MHz, depending on how lossy

22
the material is. Below about 5 MHz, the measured data often became unstable. This problem is consistent with all T/R measurements performed in transmission lines and is caused by difficulty in resolving small phase differences at these low frequencies. When this program was used at frequencies above about 100 MHz, the results were also unstable. We believe that this problem was

caused by inaccurate estimates of the open standard capacitance Q^ at these frequencies, due to including insufficient higher-order TM^n modes in the full-field analysis. At 1000 MHz, the 76.8 mm

open standard has a diameter d = 0.26/?. Contrast this with the 7 mm open standard, where d =

0.023 A Because the diameter of the open standard represents a significant fraction of the wavelength

at these frequencies, accurate computation of the fringing capacitance using a full-field solution

requires that many modes be included in the field analysis. For our estimate, we included only four

modes and it is apparent that this was insufficient. Because of this problem, the NIST measurement

software that utilizes the coaxial shielded-open technique has since been modified to incorporate

additional modes up to a total of eight, yielding more stable and reliable data [13].

The authors gratefully acknowledge the contributions of James Baker-Jarvis and Michael Janezic,

who provided software and technical guidance for estimating the fringing capacitance of the open

standard used during OSLT calibrations. We also acknowledge the assistance of Douglas Gallagher

and James Boyd of the NIST Instrument Shop for fixture design and fabrication, of Bud O'Connor

of Colorado Precision Optics, Longmont, CO for specimen preparation and of Glen Sherwood for

dimensional metrology of the specimens. We also acknowledge the help of Eric Medaugh, of the

Lockheed Martin Corporation, for providing the copper tubing used in hardware fabrication.

REFERENCES

[1] ASTM Standard D 5568-95, Standard test method for measuring relative complex

permittivity and relative magnetic permeability for solid materials at microwave frequencies.

In 1999 Annual Book of ASTM Standards, Vol. 10.02, Electrical Insulation (II). ASTM,

West Conshohocken, PA 19428.

[2] Nicolson, A.M.; Ross, G.F. Measurement of the intrinsic properties of materials by time

domain techniques, IEEE Trans. Instrum. Meas., IM-19: 377-382; Nov. 1970.

[3] Weir, W.B. Automatic measurement of complex dielectric constant and permeability at microwave frequencies, Proc. IEEE, 62: 33-36; Jan. 1974.

[4] HP 85071 A Materials Measurement Software, Hewlett-Packard Co.; 1990.

[5] Baker-Jarvis, JR.; Janezic, M.D.; Grosvenor, Jr., J.H; Geyer, R.G. Transmission/ reflection

and short-circuit line methods for measuring permittivity and permeability, Natl. Inst. Stand.

Technol. Tech. Note 1355-R; Dec. 1993.

23
[6] Weil, CM.; Janezic, M.D.; Vanzura E.J. Intercomparison of permeability and permittivity

measurements using the transmission/reflection method in 7 and 14 mm coaxial air lines, Natl.

Inst. Stand. Technol. Tech. Note 1386, March 1997.

[7] Mattar, K.E.; Watters, D.G.; Brodwin, M.E. Influence of wall contacts on measured complex

permittivity spectra at coaxial line frequencies, IEEE Trans. Microwave Theory Tech., 39(3):

532-537; 1991.

[8] Al-Qadi, I.L.; Riad, S.M.; Mostaf, R.; Su, W. Design and Evaluation of a Coaxial

Transmission Line Fixture to Characterize Portland Cement, Constr. Build. Mater., 11(3):

163-173; 1997.

[9] Teleplex, Inc. Catalog (Producers of Alford Electronics, Components, and Instruments)

Woburn, MA, 01801; 1992.

[10] Hewlett-Packard operating and programming manual: HP 851 OB network analyzer, HewlettPackard Co., Santa Rosa, CA; 1987.

[11] Baker-Jarvis, J.R. Transmission/reflection and short-circuit Hne permittivity measurements,

Natl. Inst. Stand. Technol. Tech. Note 1341; July 1990.

[12] Bianco, B.; Corano, A.; Gogiosi, L.; Ridella, S.; Parodi, M. Open-circuited coaxial lines as standards for microwave measurements. Electronics Letters, 16(10): 373-374; May 1980.

[13] Baker-Jarvis, JR.; Janezic, M.D.; Jones, CA. Shielded open-circuited sample holder for

dielectric measurements of solids and liquids, IEEE Trans. Instrum. Meas., 47(2): 338-344;

April 1998.

[14] Baker-Jarvis, JR.; Geyer, R.G; Grosvenor, Jr., J.H.; Janezic, M.D.; Jones, C.A.; Riddle,

B.F.; Weil, CM.; Krupka, J. Dielectric characterization of low-loss materials: a comparison

of techniques, IEEE Trans. Dielect. Elect. Insul., 5(4): 571-577; Aug. 1998.

[15] Arai, M.; Binner, J.G.P.; Bowden, A.L.; Cross, T.E.; Evans, N.G.; Hamlyn, M.G.; Hutcheon,

R.; Morin, G; Smith B. Elevated temperature dielectric property measurements: results of

a parallel measurement programme, in Microwaves, Theory and Applications in Materials

Processing II, Ceramic Trans. 36: 539-546; 1993.

24
APPENDIX A.

Machine Drawings of Coaxial Air Line System Hardware

25
v±^:^

Figure Al. 102 mm long specimen-holder assembly.

W

5.25

^

71^

:iL

7K

4.375 3.025 ±

Note: 60* between 6 bolt holes - 0.405 diameter

180* between alignment holes - 0.25 diameter

6 each bolt holes • 0.405 diameter

2 each alignment

holes (1 with pin) 0.25 diameter

Figure A2. Flange for 76.8 mm (3.025 in) diameter coaxial air-line components (all dimensions in

inches).

26

Z.702-

^7t-

•t.002-

-2.032-

•2.077- l-^f-

#1.250 #Uia.2JB

—0.0W —0.1 90

•1.013

ua. A-A

•X 44.7

Figure A3. Details of connection bullet (all dimensions in inches).

28
AhWJIS

0.201 iX K0lJ5O

SCCT.

sccr »-t

ftO.«90 SCCT. -•

r?c

<^ > 11 r (>M|

29
T—orau Awo ^A^

\ lO-OaUWC T.I 40 MAX Ulrf.oy>ttTATn

i

090

-I h sea A-A

0.2MJEID

tiitXi

>2X 0.2Mtkfl<imU

COUALLY SPACCP l4-lg.001»|A|8

«X 13/32 IMHU

COUAILY SfACCD

i4-io.ojo»imr

•B- —aiw

0.1 so

0.060 0.010

ftO.043

—aioo

2X 0.1! GEBn

190 TMW ozom A I B ICI

• 1.320

• 1.155

Figure A4. Details of short-circuit standard (all dimensions in inches).

30
lUUSO

SCCT A-A

•X 45-

.121 THWU

14-1(^.015 a I aTTI

Se*u< ex

—0-331

4^-•0-573 •0300

n/r

31
xy|-A-io.ooTTL|

3.024 (^ ± 0.001

Sample Thickness: 0.25 ^ i^ 0.75

Figure A5. Specifications for material specimen (all dimensions in inches).

32
APPENDIX B.

Listing for External OSLT Calibration Program

Language

Author

Date

HT BASIC

C.A. Jones

August 1994

33
100 ! TWOPORT Version 1.0 Last Revision 08/12/94 14:35

102 ! purge "a:\twoport"

104 ! re-save "a:\twoport3"

106 ! re-save "b:\twoport3"

108 ! re-save "c:\jones\twoport2"

110 ! 112 Init_com:

!

114 RAD

116 OPTION BASE 1 118 C(M /Measurement/ COMPLEX J

120 COti /Measurement/ REAL Cap (801) , Beta (801)

122 COti /Measurement/ COMPLEX Sllm(801) , S21m(801) , S12m(801) , S22m(801)

124 CO! /Measurement/ COMPLEX Sllc (801) , S21c (801) , S12c (801) , S22c (801)

126 COti /Measurement/ INTEGER Datacount,REAL Freq(801)

128 COM /Calibration/ CCMPLEX Sllm_short (801) , Sllm_open (801) , Sllm_load (801)

130 CCM /Calibration/ COMPLEX S22m_short (801) , S22m_open (801) , S22m_load (801)

132 CCM /Calibration/ COMPLEX Sllt_short (801) , Sllt_open (801) , Sllt_load (801)

134 CCM /Calibration/ COMPLEX S22t_short (801) , S22t_open (801) , S22t_load (801)

136 COM /Calibration/ COMPLEX S12m_thru (801) , S12m_rev(801) , S12m_isol (801)

138 CO! /Calibration/ COMPLEX S21m_thru (801) , S21m_rev(801) , S21m_isol (801)

140 COM /Calibration/ COMPLEX S12t_thru (801) , S12t_rev(801) , S12t_isol (801)

142 COM /Calibration/ COMPLEX S21t_thru (801) , S21t_rev(801) , S21t_isol (801)

144 COM /Calibration/ REAL Short_re (801) , Short_im(801) , Open_re (801) ,0pen_im(8

146 COM /Calibration/ REAL Load_re (801) ,Load_im(801) ,Thru_re (801) ,Thru_im(801

148 COti /Calibration/ REAL Rev_re (801) , Rev_im(801) , Isol_re (801) , Isol_im(801)

150 CC»I /Error_terms/ COMPLEX Edf (801) , Erf (801) , Esf (801) , Exf (801) , Etf (801) ,E1

152 COti /Error_terms/ COMPLEX Edr (801) , Err (801) , Esr (801) , Exr (801) ,Etr (801) ,E1

154 COM /Error_terms/ COMPLEX T1,T2,T3,M1,M2,M3, Denom(801)

156 COM /Substitutions/ COMPLEX CI (801) ,C2 (801) ,C3 (801) ,C4 (801)

158 COM /Addresses/ INTEGER Plotter_addr, Printer_addr,Nwa_addr

160 COM /File/Filename$ [30] , Diskdrive$ [30] , Path$ [200] , Description$ [40] , INTEGE

162 ! 164 Init_var:

!

166 INTEGER Preamble, Size

168 DIM Tl$ [5500] ,T2$ [5500] ,T3$ [5500] ,T4$ [5500]

170 DIM Freq_data(340) , Real_open (340) , Imag_open (340) ,Xa(20) , Yal (20) , Ya2 (20)

172 ! 174 Init_const:!

176 J=CMPLX(0,1)

178 ! 180 Init_keys:

!

182 CONTROL KBD, 15;1

184 CONTROL CRT, 12;

186 SET KEY 0, " " 188 SET KEY 1, "

" 190 SET KEY 2, "

" 192 SET KEY 3, "

" 194 SET KEY 4," " 196 SET KEY 5, "

" 198 SET KEY 6, "

" 200 SET KEY 7," " 202 SET KEY 8," " 204 SET KEY 9, "

" 206 SET KEY 10," " 208 ! 210 Main_menu:!

212 OFF KEY

214 CLEAR SCREEN

216 Prty=VAL(SYSTEM$ ("SYSTEM PRIORITY") ) +1

?1R ON KFY LARF.T, "KnH nroaram" . Prtv OOSTTR Fnd nronram

34
220 ON KEY 2 LABEL "Read NWA",Prty GOSUB Read_nwa

222 ON KEY 3 LABEL "Calibrate NWA",Prty GOSUB Calibrate_nwa

224 ON KEY 4 LABEL "Calc errors", Prty GOSUB Calc_errors

225 ON KEY 5 LABEL "load stan",Prty GOSUB Load_stan

227 ON KEY 6 LABEL "Load errors", Prty GOSUB Load_cal

228 ON KEY 7 LABEL "Read S-parms", Prty GOSUB Read_spanns

230 ON KEY 8 LABEL "Correct S-parms", Prty GOSUB Correct_sparms

232 ON KEY 9 LABEL "Save data", Prty GOSUB Save_data

234 Done=0

236 Prior_menu=0

238 DISP "Please Select One of the Softkeys . .

.

240 LOOP

242 IF Done THEN GOTO Main_menu

244 EXIT IF Prior_menu

246 END LOOP

248 ! 250 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

252 ! Setup keys so the person can decide when they want to do

254 ! which calibration

256 ! 258 Calibrate_nwa : ! 260 ! 262 REDIM Sllm_short (Datacount) , Sllt_short (Datacount)

264 REDIM Sllm_open (Datacount) , Sllt_open (Datacount)

266 REDIM Sllm_load (Datacount) , Sllt_load (Datacount)

268 REDIM S22m_short (Datacount) , S22t_short (Datacount)

270 REDIM S22m_open (Datacount) ,S22t_open (Datacount)

272 REDIM S22m_load (Datacount) , S22t_load (Datacount)

274 REDIM S12m_thru (Datacount) , S12t_thru (Datacount)

276 REDIM S12m_rev (Datacount) , S12t_rev (Datacount)

278 REDIM S12m_isol (Datacount) , S12t_isol (Datacount)

280 REDIM S21m_thru (Datacount) ,S21t_thru (Datacount)

282 REDIM S21m_rev (Datacount) , S21t_rev (Datacount)

284 REDIM S21m_isol (Datacount) , S21t_isol (Datacount)

286 ! 288 Menu: ! 290 OFF KEY

292 CLEAR SCREEN

294 Prty=VAL(SYSTEM$( "SYSTEM PRIORITY") ) +1

296 ON KEY LABEL "Prior menu", Prty GOSUB Prior_menu

298 ON KEY 7 LABEL "Reflection", Prty GOSUB Reflection

300 IF Flag7=l THEN

302 ON KEY 7 LABEL "Reflection*", Prty GOSUB Reflection

304 END IF

306 ! 308 ON KEY 8 LABEL "Transmission", Prty GOSUB Transmission

310 IF Flagll=l THEN'

312 ON KEY 8 LABEL "Transmission*", Prty GOSUB Transmission

314 END IF

316 ! 318 ON KEY 9 LABEL "Isolation", Prty GOSUB Isolation

320 IF Flagl3=l THEN

322 ON KEY 9 LABEL "Isolation*", Prty GOSUB Isolation

324 END IF

326 ! 328 Done=0

330 Prior_menu=0

332 DISP "Please select One of the Softkeys..."

334 LOOP

336 IF Done THEN GOTO Menu

35
338 EXIT IF Prior_menu

340 END LOOP

342 Done=l

344 Prior_menu=0

346 RETURN

348 ! 350 Read_nwa: ! 352 DISP "Reading data from NWA, Please wait...";

354 ASSIGN 0Nwa TO 716

356 ASSIGN @Nwa_data TO 716; FORMAT OFF

358 ASSIGN 0Nwa_sysb TO 717

360 Calc_freq: ! 362 OUTPUT 0Nwa;"STAR;OUTPACTI;"

364 ENTER @Nwa;Start_freq

366 OUTPUT @Nwa;"STOP;OUTPACTI;"

368 ENTER 0Nwa; Stop_freq

370 OUTPUT @Nwa;"POIN;OUTPACTI;"

372 ENTER @Nwa;Num_points

374 ! 376 Datacount=Num_points

377 ! 378 ! for testing

379 ! Datacount=201

380 ! Start_freq=4.5E+7

381 ! Stop_freq=l.E+9

383 ! 384 FOR 1=1 TO Datacount

385 Freq(I)=Start_freq+( ( (Stop_freq-Start_freq) / (Datacount-1) )* (I-l)

)

386 NEXT I 387 WAIT 1.5

388 Done=l

390 RETURN

392 ! 394 Reflection: ! 396 Menu_l: ! 398 OFF KEY

400 CLEAR SCREEN

402 Prty=VAL(SYSTEM$ ("SYSTEM PRIORITY") )+l

404 ON KEY LABEL "Prior menu",Prty GOSUB Prior_menu

406 ! 408 ON KEY 2 LABEL "Port 1 Short", Prty GOSUB Meas_prtl_short

410 IF Flag2«=l THEN

412 ON KEY 2 LABEL "Port 1 Short*", Prty GOSUB Meas_prtl_short

414 END IF

416 ! 418 ON KEY 3 LABEL rPort 2 Short", Prty GOSUB Meas_prt2_short

420 IF Flag3=l THEN

422 ON KEY 3 LABEL "Port 2 Short*", Prty GOSUB Meas_prt2_short

424 END IF

426 ! 428 ON KEY 4 LABEL "Port 1 Open ",Prty GOSUB Meas_portl_open

430 IF Flag4=l THEN

432 ON KEY 4 LABEL "Port 1 Open*", Prty GOSUB Meas_portl_open

434 END IF

436 ! 438 ON KEY 5 LABEL "Port 2 Open ",Prty GOSUB Meas_port2_open

440 IF Flag5=l THEN

442 ON KEY 5 LABEL "Port 2 Open*", Prty GOSUB Meas_port2_open

444 END IF

446 !

36
448 ON KEY 6 LABEL "Port 1 Load ",Prty GOSUB Meas_portl_load

450 IF Flag6=l THEN

452 ON KEY 6 LABEL "Port 1 Load*",Prty GOSUB Meas_j)ortl_load

454 END IF

456 • 458 ON KEY 7 LABEL "Port 2 Load ••,Prty GOSUB Meas_port2_load

460 IF Flag7=l THEN

462 ON KEY 7 LABEL "Port 2 Load*",Prty GOSUB Meas_port2_load

464 END IF

466 Done=0

4 68 Prior_menu=0

470 DISP "Please select One of the Softkeys..."

472 LOOP

474 IF Done THEN GOTO Menu_l

476 EXIT IF Prior_menu

478 END LOOP

480 Done=l

482 Prior_menu=0

484 RETURN

486 ! 488 Transmission: ! 490 DISP "Connect Ports 1 and 2 together and press Enter...";

492 INPUT Dununy$

494 Menu_2: ! 496 OFF KEY

498 Prty=VAL(SYSTEM${ "SYSTEM PRIORITY") ) +1

500 ON KEY LABEL "Prior menu",Prty GOSUB Prior_menu

502 ! 504 ON KEY 2 LABEL "Port 1 for",Prty GOSUB Meas_s21_thru

506 IF Flag8=l THEN

508 ON KEY 2 LABEL "Port 1 for*",Prty GOSUB Meas_521_thru

510 END IF

512 ! 514 ON KEY 3 LABEL "Port 2 for",Prty GOSUB Meas_sl2_thru

516 IF Flag9=l THEN

518 ON KEY 3 LABEL "Port 2 for*",Prty GOSUB Meas_sl2_thru

520 END IF

522 ! 524 ON KEY 4 LABEL "Port 1 rev",Prty GOSUB Meas_s21_rev

526 IF Flagl0=l THEN

528 ON KEY 4 LABEL "Port 1 rev*",Prty GOSUB Meas_s21_rev

530 END IF

532 ! 534 ON KEY 7 LABEL "Port 2 rev",Prty GOSUB Meas_sl2_rev

536 IF Flagll=l THEN

538 ON KEY 7 LABEL "Port 2 rev*",Prty GOSUB Meas_sl2_xev

540 END IF

542 ! 544 Done=0

546 Prior_menu=0

548 DISP "Please Select One of the Softkeys..."

550 LOOP

552 IF Done THEN GOTO Menu_2

554 EXIT IF Prior_menu

556 END LOOP

558 Done=l

560 RETURN

562 ! 564 Isolation: ! 566 !

37
568 DISP "Attach 50 ohm loads to port 1 and 2 and press Enter.,

570 INPUT Duinmy$

572 ! 574 Menu_3: ! 576 OFF KEY

578 Prty=VAL(SYSTEM$ ("SYSTEM PRIORITY") ) +1

580 ON KEY LABEL "Prior menu",Prty GOSUB Prior_menu

582 ON KEY 2 LABEL "Port 1 Isol",Prty GOSUB Meas_s21_isol

584 IF Flagl2=l THEN

586 ON KEY 2 LABEL "Port 1 Isol*",Prty GOSUB Meas_s21_isol

588 END IF

590 ! 592 ON KEY 3 LABEL "Port 2 Isol",Prty GOSUB Meas_sl2_isol

594 IF Flagl3=l THEN

596 ON KEY 3 LABEL "Port 2 Isol*",Prty GOSUB Meas_sl2_isol

598 END IF

600 ! 602 Done=0

604 Prior_menu=0

606 DISP "Please Select One of the Softkeys " 608 LOOP

610 IF Done THEN GOTO Menu_3

612 EXIT IF Prior_menu

614 END LOOP

616 Done=l

618 RETURN

620 Prior_nienu: ! 622 Prior_menu=l

624 RETURN

626 ! 628 Meas_prtl_short: ! 630 DISP "Please Connect the Short at Port 1 and Press Enter...

632 INPUT Duininy$

634 DISP "Measuring the Short at Port 1..."

636 OUTPUT 0Nwa;"Sll;"

638 OUTPUT 0Nwa;"TITL ""MEASURING STANDARD, PLEASE WAIT..."";"

640 ! OUTPUT 0Nwa;"NUMG 64;"

642 OUTPUT @Nwa;"SING;"

644 OUTPUT 0Nwa;"FORM3;OUTPDATA;"

646 ENTER 0Nwa_data; Preamble; Size, Sllm_short (*)

648 OUTPUT 0Nwa;"TITL """";"

650 Flag2=l

652 Done=l

654 RETURN

656 ! 658 Meas_portl_open: !. 660 DISP "Please Connect the Open at Port 1 and Press Enter " 662 INPUT Dummy$

664 DISP "Measuring the Open at Port 1 " 666 OUTPUT 0Nwa;"Sll;"

668 OUTPUT 0Nwa;"TITL ""MEASURING STANDARD, PLEASE WAIT..."";"

670 ! OUTPUT 0Nwa;"NUMG 64;"

672 OUTPUT 0Nwa;"SING;"

674 OUTPUT 0Nwa;"FORM3;OUTPDATA;"

676 ENTER @Nwa_data; Preamble;Size, Sllm_open (*) 678 OUTPUT @Nwa;"TITL ""••";" 680 Flag4=l

682 Done=l

684 RETURN

686 !

38
688 Meas_portl_load: ! 690 DISP "Please Connect the Load at Port 1 and Press Enter.

692 INPUT Duinmy$

694 DISP "Measuring the Load at Port 1..."

696 OUTPUT 0Nwa;"Sll;"

698 OUTPUT 0Nwa;"TITL ""MEASURING STANDARD, PLEASE WAIT..."";

700 ! OUTPUT 0Nwa;"NUMG 64;"

702 OUTPUT @Nwa;"SING;"

704 OUTPUT eNwa;"F0RM3;0UTPDATA;"

706 ENTER @Nwa_data; Preamble;Size, Sllm_load (*)

708 OUTPUT 0Nwa;"TITL """";"

710 Flag6=l

712 Done=l

714 RETURN

716 ! 718 Measjprt2_short: ! 720 DISP "Please Connect the Short at Port 2 and Press Enter.

722 INPUT Duirany$

724 DISP "Measuring the Short at Port 2..."

726 OUTPUT 0Nwa;"S22;"

728 OUTPUT 0Nwa;"TITL ""MEASURING STANDARD, PLEASE WAIT..."";

730 ! OUTPUT 0Nwa;"NUMG 64;"

732 OUTPUT 0Nwa;"SING;"

734 OUTPUT 0Nwa;"FORM3;OUTPDATA;"

736 ENTER 0Nwa_data; Preamble; Size, S22m_short (*)

738 OUTPUT 0Nwa;"TITL "••"";" 740 Flag3=l

742 Done=l

744 RETURN

746 ! 748 Meas_port2_open: ! 750 DISP "Please Connect the Open at Port 2 and Press Enter..

752 INPUT Duinmy$

754 DISP "Measuring the Open at Port 2..."

756 OUTPUT 0Nwa;"S22;"

758 OUTPUT 0Nwa;"TITL ""MEASURING STANDARD, PLEASE WAIT..."";

760 • OUTPUT 0Nwa;"NUMG 64;"

762 OUTPUT 0Nwa;"SING;"

764 OUTPUT 0Nwa;"FORM3;OUTPDATA;"

766 ENTER 0Nwa_data; Preamble;Size,S22m_open (*)

768 OUTPUT 0Nwa;"TITL """";"

770 Flag5=l

772 Done=l

774 RETURN

776 ! 778 Meas_port2_load: ! 780 DISP "Please Connect the Load at Port 2 and Press Enter..

782 INPUT Duirany$

784 DISP "Measuring the Load at Port 2..."

786 OUTPUT 0Nwa;"S22;"

788 OUTPUT 0Nwa;"TITL ""MEASURING STANDARD, PLEASE WAIT..."";

790 ! OUTPUT 0Nwa;"NUMG 64;"

792 OUTPUT 0Nwa;"SING;"

794 OUTPUT 0Nwa;"FORM3;OUTPDATA;"

796 ENTER @Nwa_data; Preamble; Size, S22m_load (*)

798 OUTPUT @Nwa;"TITL """";"

800 Flag7=l

802 Done=l

804 RETURN

806 !

39
808 ! 810 Meas_s21_thru: ! 812 DISP "Measuring the s21 thru..."

814 OUTPUT eNwa;"S21;"

816 OUTPUT @Nwa;"TITL ""MEASURING STANDARD, PLEASE WAIT.

818 ! OUTPUT @Nwa;"NUMG 64;"

820 OUTPUT @Nwa;"SING;"

822 OUTPUT @Nwa; "F0RM3;0UTPDATA;

824 ENTER @Nwa_data; Preamble; Size, S21m_thru (*) 826 OUTPUT @Nwa;"TITL """";"

828 Flag8=l

830 Done=l

832 RETURN

834 ! 836 Meas_sl2_thru: ! 838 DISP "Measuring the sl2 thru..."

840 OUTPUT @Nwa;"S12;"

842 OUTPUT @Nwa;"TITL ""MEASURING STANDARD, PLEASE WAIT.

844 ! OUTPUT @Nwa;"NUMG 64;"

846 OUTPUT 0Nwa;"SING;"

848 OUTPUT @Nwa;"F0RM3;0UTPDATA;"

850 ENTER @Nwa_data; Preamble; Size, S12m_thru {*)

852 OUTPUT eNwa;"TITL """";"

854 Flag9=l

856 Done=l

858 RETURN

860 ! 862 Meas_s21_rev: ! 864 DISP "Measuring the s21 reverse transmission..."

866 OUTPUT @Nwa;"Sll;"

868 OUTPUT @Nwa;"TITL ""MEASURING STANDARD, PLEASE WAIT.

870 ! OUTPUT @Nwa;"NUMG 64;"

872 OUTPUT @Nwa;"SING;"

874 OUTPUT @Nwa;"F0RM3;0UTPDATA;"

876 ENTER @Nwa_data; Preamble;Size, S21m_rev(*)

878 OUTPUT @Nwa;"TITL """";"

880 FlaglO=l

882 Done=l

884 RETURN

886 ! 888 Meas_sl2_rev: ! 890 DISP "Measuring the sl2 reverse transmission..."

892 OUTPUT 0Nwa;"S22;"

894 OUTPUT @Nwa;"TITL ""MEASURING STANDARD, PLEASE WAIT.,

896 ! OUTPUT 0Nwa; "NUMG 64;"

898 OUTPUT 0Nwa;"SING;"

900 OUTPUT 0Nwa;"FORM3;OUTPDATA;"

902 ENTER 0Nwa_data; Preamble; Size, S12m_rev(*)

904 OUTPUT 0Nwa;"TITL """";"

906 ! 908 Flagll=l

910 Done=l

912 RETURN

914 ! 916 ! 918 ! 920 Meas_s21_isol: ! 922 DISP "Measuring the s21 isolation..."

924 OUTPUT @Nwa;"S21;"

926 OUTPUT 0Nwa;"TITL ""MEASURING STANDARD, PLEASE WAIT..

40
OUTPUT @Nwa;"NUMG 64;"

OUTPUT @Nwa;"SING;"

OUT PUT @ Nwa ; " F0RM3 ; OUT P DATA;

ENTER @Nwa_data; Preamble; Size, S21m_isol (*) OUTPUT @Nwa;"TITL """";"

Flagl2=l

Done=l

RETURN

928

930

932

934

936

938

940

942

944 ! 946 Meas sl2 isol:

DISP "Measuring the sl2 isolation..."

OUTPUT @Nwa;"S12;"

OUTPUT @Nwa;"TITL ""MEASURING STANDARD, PLEASE WAIT.

OUTPUT 0Nwa;"NUMG 64;"

OUTPUT @Nwa;"SING;"

OUTPUT @Nwa ; "F0RM3 ; OUTPDATA;

ENTER eNwa_data;Preamble;Size,S12m_isol(*)

OUTPUT @Nwa;"TITL """";"

Flagl3=l

Done=l

RETURN

948

950

952

954

956

958

960

962

964

966

968

970

972

974

976

978 ! 980 Read_sparms:

982 Read slim: !

I

I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I

For device under test

984

986

988

990

992

994

996

998

1000

1002

1004

1006

1008

1010

1012

1014

1016

1018

1020

1022

1024

1026 ! 1028 Read_s21:

1030 DISP "Measuring s21..."

1032 OUTPUT @Nwa;"s21;"

1034 OUTPUT @Nwa;"TITL ""MEASURING S21..."";"

1036 ! OUTPUT @Nwa;"NUMG 64;"

1038 OUTPUT @Nwa;"SING;"

1040 OUTPUT @ Nwa ;"F0RM3; OUTPDATA;"

1042 ENTER @Nwa_data; Preamble; Size, S21m(*)

1044 OUTPUT 0Nwa;"TITL """";"

1046 !

OFF KEY

CLEAR SCREEN

ASSIGN @Nwa TO 716

ASSIGN @Nwa_data TO 716; FORMAT OFF

ASSIGN 0Nwa_sysb TO 717

REDIM Sllm(Datacount) ,Sllc (Datacount)

REDIM S21m(Datacount) , S21c (Datacount)

REDIM S12m(Datacount) , S12c (Datacount)

REDIM S22m (Datacount) , S22c (Datacount)

DISP "Please connect the device under test and press Enter.

INPUT Dummy$

DISP "Measuring sll..."

OUTPUT (?Nwa;"sll;"

OUTPUT @Nwa; "TITL ""MEASURING Sll. .."";"

OUTPUT @Nwa;"NUMG 64;"

OUTPUT 0Nwa;"SING;"

OUTPUT 0Nwa;"FORM3;OUTPDATA;

ENTER @Nwa_data; Preamble; Size, Slim (*)

OUTPUT 0Nwa;"TITL """";"

41
1048 Read_sl2:

!

1050 DISP "Measuring sl2..."

1052 OUTPUT @Nwa;"sl2;"

1054 OUTPUT @Nwa;"TITL ""MEASURING S12..."";"

1056 ! OUTPUT 0Nwa;"NUMG 64;"

1058 OUTPUT 0Nwa;"SING;"

1060 OUTPUT @Nwa;"F0RM3;0UTPDATA;"

1062 ENTER @Nwa_data; Preamble; Size, S12m (*) 1064 OUTPUT @Nwa;"TITL """";"

1066 ! 1068 Read_s22:

!

1070 DISP "Measuring s22..."

1072 OUTPUT @Nwa;"s22;"

1074 OUTPUT @Nwa;"TITL ""MEASURING S22..."";"

1076 ! OUTPUT @Nwa; "NUMG 64;"

1078 OUTPUT @Nwa;"SING;"

1080 OUTPUT @Nwa; "F0RM3;0UTPDATA;

1082 ENTER GNwa_data; Preamble; Size, S22m(*)

1084 OUTPUT eNwa;"TITL """";"

1086 ! 1088 DISP "Device under test has been measured...";

1090 ! 1092 Done=l

1094 RETURN

1096 ! 1098 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

1100 ! 1102 Calc_errors:

!

1104 ! 1106 REDIM Edf (Datacount) , Erf (Datacount) , Esf (Datacount) , Exf (Datacount) , Etf (Dat

1108 REDIM Edr (Datacount) , Err (Datacount) , Esr (Datacount) , Exr (Datacount) , Etr (Dat

1110 REDIM CI (Datacount) , C2 (Datacount) , C3 (Datacount) , C4 (Datacount)

1112 REDIM Denom (Datacount)

1114 REDIM Short_re (Datacount) , Short_im (Datacount) , Open_re (Datacount) ,Open_im(

1116 REDIM Load_re (Datacount) , Load_ini( Datacount) ,Thru_re (Datacount) ,Thru_ira(Da

1118 REDIM Rev_re (Datacount) , Rev_im( Datacount) , Isol_re (Datacount) , Isol_im(Data

1120 REDIM Cap (Datacount) , Beta (Datacount)

1122 ! 1124 !//////////////////

1126 ! 1128 DISP "Are you working with the open circuit model (0) , or"

1130 WAIT 1 1132 INPUT "Stuchly's model? (S) (0=1, S=0) ", Answer

1134 IF (Answer=l) THEN

1136 DISP "Correcting error coefficients, Please wait...";

1138 WAIT 1 1140 GOSUB Jims_open_model

1142 ELSE

1144 DISP "Correcting error coefficients. Please wait...";

1146 WAIT 1 1148 GOSUB Hp_open_model

1150 END IF

1152 Done=l

1154 RETURN

1156 ! 1158 Jims_open_model:

!

1160 Theory_open: ! 1162 ASSIGN @File TO "a: \oc77mm2 .dat"; FORMAT ON

1163 ENTER @File; Counter

1164 PRINT "counter is ", Counter

42
1166 ENTER 0File; Dummy

1167 PRINT "dummy number is ".Dummy

1168 ENTER GFile; Description$

1170 DISP "Loading table for Sll data for open..."

1171 FOR 1=1 TO Counter

1172 ENTER @File; Freq_data (I) , Real_open (I) , Imag_open (I) 1173 Sllt_open(I)=CMPLX{Real_open{I) , Imag_open (I)

)

117 4 S22t_open(I)=CMPLX{Real_open{I) ,Imag_open(I)

1175 NEXT I 1299 GOTO Reflect_errors

1300 ! 1301 Hp_open_model:

!

1302 Theory_openl:

!

1303 ! 1304 !Coeff_7mm: ! 1306 ! Capnot=1.5092E-12

1307 ! Capl=8.92E-27

1308 ! Cap2=5.8051E-33

1309 ! Cap3=8.310E-43

1310 ! 1311 Coeff_3_l_8: ! 1312 Capnot=1.3007E-12

1313 Capl=2.4563E-24

1314 Cap2=8.0290E-32

1315 Cap3=1.9978E-41

1316 ! 1318 Znot=50

1319 FOR 1=1 TO Datacount

1320 Cap(I)=Capnot+Capl*Freq(I)+Cap2* (Freq{I) ) ^2+Cap3* (Freq(I) ) ^3

1321 Beta(I)=2*(ATN(2*PI*Freq(I)*Cap(I)*Znot)

)

1322 Sllt_open(I)=EXP(-J*Beta(I) ) 1323 S22t_open(I)=EXP(-J*Beta(I) ) 1324 NEXT I 1325 PRINT "cap(l) is ",Cap(l)

1326 PRINT "beta(l) is ",Beta(l)

1327 PRINT "sllt_open is ", Sllt_open (1) 1328 WAIT 1.4

1329 ! 1330 Reflect_errors:

!

1331 Theory_short :

!

1332 FOR 1=1 TO Datacount

1333 DISP "Calculating theoretical Sll (short) for point # ";I 1334 Sllt_short(I)=CMPLX(-l,0)

1335 NEXT I 1336 FOR 1=1 TO Datacount

1337 DISP "Calculating theoretical S22 (short) for point # ";I 1338 S22t_short(i)=CMPLX(-l,0)

1339 NEXT I 1340 Theory_load:

!

1341 FOR 1=1 TO Datacount

1342 DISP "Calculating theoretical Sll (load) for point # ";I 1343 Sllt_load(I)=CMPLX(0,0)

134 4 NEXT I 1345 FOR 1=1 TO Datacount

1346 DISP "Calculating theoretical S22 (load) for point # ";I 1347 S22t_load(I)=CMPLX(0,0)

1348 NEXT I 1349 ! 1350 ! 1351 Calc error net:!

43
1352

1353

1354

1355

1356

1357

1358

1360

1364

1365

1366

1367

1368

1369

1370

1371

1372

1373

1374

1375

1376

1377

1378

1379

1380

1381

1382

1384

1386

1388

1390

1392

1394

1396

1398

1400

1402

1404

1406

1408

1410

1412

1414

1416

1418

1420

1422

1424

1426

1428

1430

1432

1434

1436

1438

1440

1442

1444

1446

1448

DISP "Calculating error terms for port 1..."

FOR 1=1 TO Datacount

Tl=Sllt_short(I)

T2=Sllt_open(I)

T3=Sllt_load(I)

Ml=Sllm_short(I)

M2=Sllm_open(I)

M3=Sllm_load(I)

I Edf (I) = (T1*T2*M3* (M1-M2) +T1*T3*M2* {M3-M1) +T2*T3*M1* (M2-M3) ) / (T1*T2* (M

Esf (1)-= (Tl* (M2-Edf (I) ) +T2* (Edf (I) -Ml) ) / (T1*T2* (M2-M1) ) Erf (I)=((M1-Edf (I) )*(l-Tl*Esf (I) )/Tl)

NEXT I

I DISP "Calculating error terms for port 2..,"

FOR 1=1 TO Datacount

Tl=S22t_short (I) T2=S22t_open(I)

T3=S22t_load(I)

Ml=S22m_short(I)

M2=S22m_open(I)

M3=S22m_load(I)

I Edr (I) = (T1*T2*M3* (M1-M2) +T1*T3*M2* (M3-M1) +T2*T3*M1* (M2-M3) ) / (T1*T2* (M

Esr(I)=(Tl*(M2-Edr(I) ) +T2* (Edr (I) -Ml) ) / (T1*T2* (M2-M1)

)

Err (I)=( (Ml-Edr (I) ) * (l-Tl*Esr(I) ) /Tl)

NEXT I

!///////////////

Isol_errors:

!

Calc_s21_isol:

!

FOR 1=1 TO Datacount

Exf (I)=S21m_isol(I)

NEXT I

ICalc_sl2_isol:

!

FOR 1=1 TO Datacount

Exr(I)=S12m_isol(I)

NEXT I

I

Trans_errors:

!

I FOR 1=1 TO Datacount

Ml=S21m_thru(I)

M2=S12m_thru(I)

M3=S21m_rev(I)

M4=S12m_rev(I)

I Elf (I)=(M3-Edf (I) )/(M3*Esf (I)+Erf (I)-Edf (I)*Esf (I)

)

Elr(I)=(M4-Edr(I))/(M4*Esr(I)+Err(I)-Edr{I)*Esr{I)

Etf (I) = (Ml-Exf (I) ) * (1-Esf (I) *Elf (I)

)

Etr (I)={M2-Exr (I) ) * (1-Esr (I) *Elr (I)

)

I NEXT I

I Done=l

RETURN

1

44
1450 Correct_sparms:

1452 Actual_sparms:

1454 ! 1456 Substitutions:!

1458 DISP "Calculating corrections for S-parms. .

. "; 1460 FOR 1=1 TO Datacount

1462 Cl{I)>=Sllm(I)-Edf (I)

1464 C2(I)=S22m(I)-Edr(I)

1466 C3(I)=S21m(I)-Exf (I) 1468 C4 (I)=S12m{I)-Exr{I)

1470 Denom(I)= (1+ ( (CI (I) *Esf (I) ) /Erf (I) ))*(!+( (C2 (I) *Esr (I) ) /Err (I) )

) - ( {C3

1472 ! 1474 Sllc(I)=(Cl(I)/Erf (I))*(l+((C2(I)*Esr(I))/Err(I)))-(Elf (I)*(C3(I)/Etf

1476 S22c(I)=(C2(I)/Err(I))*(l+({Cl(I)*Esf (I))/Erf (I)))-(Elr(I)*(C3(I)/Etf

1478 S12c(I)=(C4(I)/Etr(I))*(l+((Cl{I)/Erf (I))*(Esf (I)-Elr(I))))/Denom{I)

1480 S21c(I)={C3(I)/Etf {I))*(l+((C2(I)/Err(I))*(Esr(I)-Elf (I))))/Denora{I)

1482 ! 1484 NEXT I 1486 WAIT 2 1488 Done=l

1490 RETUflN

1492 ! 1494 Save_data:

1496 ! 1498 OFF KEY

1500 CLEAR SCREEN

1502 Prty=VAL(SYSTEM$( "SYSTEM PRIORITY") ) +1

1504 ON KEY LABEL "Prior menu",Prty GOSUB Prior_menu

1506 ON KEY 6 LABEL "Save calibration", Prty GOSUB Save_cal

1508 ON KEY 7 LABEL "Save standards", Prty GOSUB Save_stan

1510 ON KEY 8 LABEL "Save meas",Prty GOSUB Save_meas

1512 ON KEY 9 LABEL "Save sparms",Prty GOSUB Save_sparms

1514 Done=0

1516 Prior_menu=0

1518 DISP "Please select One of the Softkeys..."

1520 LOOP

1522 IF Done THEN GOTO Save_data

1524 EXIT IF Prior_menu

1526 END LOOP

1528 Done=l

1530 Prior_menu=0

1532 RETURN

1534 ! 1536 Save_sparms :

1538 ! 1540 Dut:

1542 OFF KEY

1544 CLEAR SCREEN

1546 DISP "Please enter a description of the corrected data (<=40 chars.)...";

1548 LINPUT Test$

1550 Test$=TRIM$(Test$)

1552 Description$=Test$

1554 Bitflag=0

1556 ALLOCATE Array (Datacount, 5, 2)

1558 FOR 1=1 TO Datacount

1560 Array(I,l,l)=Freq(I)

1562 Array(I,2,l)=REAL(Sllc(I))

1564 Array(I,2,2)=IMAG(Sllc(I))

1566 Array(I,3,l)=REAL(S22c(I)

1568 Array(I,3,2)=IMAG(S22c(I)

45
1570 Array{I,4,l)=REAL(S21c(I)

)

1572 Array(I,4,2)=IMAG(S21c(I)

)

1574 Array(I,5,l)=REAL(S12c(I)

1576 Array(I,5,2)=IMAG(S12c{I)

1578 NEXT I 1580 Diskdrive$="c:\jones\programs\"

1582 DISP "Please enter a filename for the corrected data (<=30 chars.)-

1584 LINPUT Filename$

1586 Path$=Diskdrive$&Filename$

1588 CREATE Path$,0

1590 ASSIGN eFile TO Path$; FORMAT ON

1592 DISP "Saving File. .

. "; Path$

1594 OUTPUT eFile;Datacount

1596 OUTPUT 0File; Bitflag

1598 OUTPUT 0File;Description$

1600 OUTPUT 0File;Array(*)

1602 ASSIGN @File TO * 1604 DISP "File saved... " 1606 WAIT 5 1608 DEALLOCATE Array (*) 1610 Done=l

1612 RETURN

1614 ! 1616 Save_meas:!

1618 Before_corr:

!

1620 OFF KEY

1622 CLEAR SCREEN

1624 DISP "Please enter a description of the measured data (<=40 chars.)

1626 LINPUT Test$

1628 Test$=TRIM$ (Test$)

1630 Description$=Test$

1632 Bitflag=0

1634 ALLOCATE Array ( Datacount, 5, 2)

1636 FOR 1=1 TO Datacount

1638 Array(I,l,l)=Freq(I)

1640 Array{I,2,l)=REAL(Sllm(I)

)

1642 Array{I,2,2)=IMAG(Sllm{I))

1644 Array(I,3,l)=REAL(S22m{I)

1646 Array(I,3,2)=IMAG(S22m(I)

)

1648 Array(I,4,l)=REAL(S21m(I))

1650 Array(I,4,2)=IMAG(S21m(I))

1652 Array(I,5,l)=REAL{S12m(I))

1654 Array{I,5,2)=IMAG(S12m(I))

1656 NEXT I 1658 Diskdrive$="c:\jones\programs\"

1660 DISP "Please enter a filename for the measured data (<=30 chars.)..

1662 LINPUT Filename$

1664 Path$=Diskdrive$&Filename$

1666 CREATE Path$,0

1668 ASSIGN 0File TO Path$; FORMAT ON

1670 DISP "Saving File. .

. "; Path$

1672 OUTPUT 0File; Datacount

1674 OUTPUT 0File; Bitflag

1676 OUTPUT 0File;De3cription$

1678 OUTPUT File; Array (*)

1680 ASSIGN 0File TO * 1682 DISP "File saved... " 1684 WAIT 5 1686 DEALLOCATE Array (*) 1688 Done=l

46
1690 RETURN

1692 ! 1694 Save_cal:

1695 OFF KEY

1696 CLEAR SCREEN

1697 ALLOCATE Array (Datacount, 13,2)

1698 FOR 1=1 TO Datacount

1699 Array(I,l,l)=Freq{I)

1700 Array(I,2,l)«=REAL(Edf (I) ) 1701 Array{I,2,2)=IMAG(Edf (I)

1702 Array(I,3,l)=REAL{Erf (I)

1703 Array(I,3,2)=IMAG(Erf (I) 1704 Array(I,4,l)=REAL(Esf (I)

1705 Array(I,4,2)=IMAG(Esf (I)

1706 Array(I,5,l)=REAL(Exf (I)

1707 Array(I,5,2)=IMAG(Exf (I)

1708 Array(I,6,l)=REAL(Etf (I) 1709 Array(I,6,2)=IMAG(Etf (I) 1710 Array(I,7,l)=REAL(Elf (I) 1711 Array(I,7,2)=IMAG(Elf (I)

1712 Array(I,8,l)=REAL(Edr (I) ) 1713 Array(I,8,2)=IMAG(Edr(I)

1714 Array(I,9,l)=REAL(Err{I)

1715 Array(I,9,2)=IMAG{Err{I)

1716 Array(I,10,l)=REAL(Esr(I)

1717 Array(I,10,2)=IMAG(Esr(I)

1718 Array(I,ll,l)=REAL(Exr(I)

1719 Array(I,ll,2)=IMAG(Exr(I)

1720 Array(I,12,l)=REAL(Etr(I)

1721 Array(I,12,2)=IMAG(Etr (I) 1722 Array(I,13,l)=REAL(Elr(I)

1723 Array(I,13,2)=IMAG(Elr(I)

1724 NEXT I 1725 Diskdrive$="c:\jones\programs\"

1726 DISP "Please enter a filename for the calibration (<30 chars.)

1727 LINPUT Filename$

1728 Path$=Diskdrive$&Filename$

1729 CREATE Path$,0

1730 ASSIGN @File TO Path$ ; FORMAT ON

1731 DISP "Saving File. .

. ";Path$

1732 OUTPUT 0File;Start_freq

1733 OUTPUT 0File;Stop_freq

1734 OUTPUT e File; Datacount

1735 OUTPUT 0File; Array ()

1736 ASSIGN 0File TO * 1737 DISP "file saved... " 1738 DEALLOCATE Array (*)

1784 Done=l

1786 RETURN

1788 ! 1790 Load_cal:

1791 OFF KEY

1792 CLEAR SCREEN

1793 Diskdrive$="c: \ jones\programs\"

1794 DISP "Please enter a filename for the cal file

1795 LINPUT Filename$

1796 Path$=Diskdrive$SFilename$

1797 ASSIGN 0File TO Path$; FORMAT ON

1798 DISP "Loading File. .

. "; Path$

1799 ENTER 0File; Start_freq

(<=30 chars.)

47
1800 ENTER @File; Stop_freq

1801 ENTER @File;Datacount

1802 ALLOCATE Array (Datacount, 13, 2)

1803 ENTER @File;Array (*) 1804 ASSIGN 0File TO * 1805 FOR 1=1 TO Datacount

1806 Freq(I)=Array(I,l,l)

1807 Edf (I)=CMPLX(Array(I,2,l) ,Array(I,2,2)

)

1808 Erf {I)=CMPLX(Array(I,3,l) ,Array(I,3,2) ) 1809 Esf {I)-CMPLX(Array(I,4,l),Array(I,4,2)

)

1810 Exf (I)=CMPLX(Array(I,5,l) ,Array(I,5,2) ) 1811 Etf (I)=CMPLX(Array(I,6,l) , Array (I, 6, 2)

)

1812 Elf (I)=CMPLX(Array(I,7,l) ,Array(I,7,2)

)

1813 Edr(I)=CMPLX(Array(I,8,l) ,Array(I,8,2)

1814 Err (I)=CMPLX(Array(I,9,l) ,Array(I,9,2)

1815 Esr (I)=CMPLX{Array{I,10,l) , Array (1, 10, 2)

)

1816 Exr (I)=CMPLX(Array{I,ll,l) , Array (1, 11, 2)

)

1817 Etr (I)=CMPLX(Array(I,12,l) , Array (1, 12, 2)

)

1818 Elr (I)=CMPLX(Array(I,13,l) ,Array (1, 13, 2)

)

1819 NEXT I 1820 DISP "File loaded.. " 1821 DEALLOCATE Array (*) 1822 Done=l

1823 RETURN

1858 ! 1859 Load_stan:

!

1860 Load_stan__portl: ! 1862 OFF KEY

18 63 CLEAR SCREEN

1864 Diskdrive$="a:\"

1865 DISP "Please enter a filename for the standards on portl (<=30 chars.)

1866 LINPUT Filename$

1867 Path$=Diskdrive$SFilename$

1868 ASSIGN @File TO Path$; FORMAT ON

1869 DISP "Loading File. .

. "; Path$

1870 ENTER @File;Start_freq

1871 ENTER 0File;Stop_freq

1872 ENTER @ File; Datacount

1873 ALLOCATE Array (Datacount, 7, 2)

1874 ENTER @ File ;Ar ray (*) 1875 ASSIGN 0File TO * 1876 FOR 1=1 TO Datacount

1877 Freq(I)=Array(I,l,l)

1878 Sllm_short(I)=CMPLX(Array(I,2,l) , Array (I, 2, 2)

)

1879 Sllm_open(I)=CMPLX(Array(I,3,l) , Array (I, 3, 2)

)

1880 Sllm_load{I)=CMPLX(Array(I,4,l) ,Array (I, 4, 2)

)

1881 S21m_thru(I)=CMPLX(Array(I,5,l) ,Array (I, 5, 2)

)

1882 S21m_isol(I)=CMPLX(Array(I,6,l) , Array (I, 6, 2)

)

1883 S21m_rev(I)=CMPLX(Array(I,7,l) , Array (I, 7, 2)

)

1884 NEXT I 1885 DISP "File loaded.. " 1886 DEALLOCATE Array (*) 1893 ! 1896 Load_stan_port2 :

!

1897 OFF KEY

1898 CLEAR SCREEN

1899 Diskdrive$="a:\"

1900 DISP "Please enter a filename for the standards on port2 (<=30 chars.)

1901 LINPUT Filename$

1902 Path$=Diskdrive$&Filename$

48
1903 ASSIGN erile TO Path$; FORMAT ON

1904 DISP "Loading File. . . "; Path$

1905 ENTER @File;Start_freq

1906 ENTER @File;Stop_freq

1907 ENTER 0File; Datacount

1908 ALLOCATE Array (Datacount, 7, 2)

1909 ENTER QFile; Array (*) 1910 ASSIGN @File TO * 1911 FOR 1=1 TO Datacount

1912 Freq(I)=Array(I,l,l)

1913 S22m_short(I)=CMPLX(Array(I,2,l) , Array (I, 2, 2)

)

1914 S22m_open(I)=CMPLX(Array(I,3,l) , Array (I, 3, 2)

)

1915 S22m_load(I)=CMPLX(Array(I,4,l),Array(I,4,2)

1916 S12m_thru(I)=CMPLX(Array(I,5,l) , Array (I, 5, 2)

)

1917 S12m_isol(I)=CMPLX(Array{I,6,l) , Array (I, 6, 2)

)

1918 S12m_rev(I)=CMPLX(Array(I,7,l),Array(I,7,2)

)

1919 NEXT I 1920 DISP "File loaded.. " 1921 DEALLOCATE Array (*)

1922 Done=l

1923 RETURN

1924 > 1925 Save_stan:

!

1926 FOR 1=1 TO Datacount

1927 Short_re (I) =REAL (Sllm_short (I)

)

1928 Short_im(I)=IMAG(Sllin_short (I) ) 1929 Open_re(I)=REAL(Sllin_open(I) ) 1930 C^en_im(I)=IMAG(Sllm_open(I)

)

1931 Load_re(I)=REAL(Sllm_load(I)

1932 Load_im(I)=IMAG(Sllm_load(I)

)

1933 Thru_re(I)=REAL(S21m_thru(I)

1934 Thru_im(I)=IMAG(S21m_thru(I)

)

1935 Isol_re(I)=REAL(S21m_isol(I)

)

1936 Isol_im(I)=IMAG(S21m_isol(I)

)

1937 Rev_re(I)=REAL(S21m_rev(I))

1938 Rev_im(I)=IMAG(S21m_rev(I)

)

1939 NEXT I 1940 OFF KEY

1941 CLEAR SCREEN

1942 ALLOCATE Array (Datacount, 7, 2)

1943 FOR 1=1 TO Datacount

1944 Array(I,l,l)=Freq(I)

1945 Array(I,2,l)=Short_re(I)

1946 Array(I,2,2)=Short_im(I)

1947 Array(I,3,l)=0pen_re(I)

1948 Array(I,3,2)=C^en_im(I)

1949 Array(I,4,l)=Load_re(I)

1950 Array(I,4,2)=Load_im(I)

1951 Array(I,5,l)=Thru_re(I)

1952 Array(I,5,2)=Thru_im(I)

1953 Array(I,6,l)=Rev_re(I)

1954 Array(I,6,2)=Rev_im(I)

1955 Array(I,7,l)=Isol_re(I)

1956 Array(I,7,2)=Isol_im(I)

1957 NEXT I 1958 Diskdrive$="c:\jones\programs\"

1959 DISP "Please enter a filename for standards on port 1 (<30 chars.)

1960 LINPUT Filename$

1961 WAIT 1.2

1962 Path$=Diskdrive$&Filename$

49
1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

2010

2012

2014

2016

2018

2020

2022

2024

2026

2028

2030

2032

2034

2036

2038

2040

2042

2044

2046

2048

2050

2052

2054

2056

CREATE Path$,0

ASSIGN GFile TO Path$; FORMAT ON

DISP "Saving File. .

. ";Path$

OUTPUT @File;Start_freq

OUTPUT @File;Stop_freq

OUTPUT @File;Datacount

OUTPUT @ File; Array (*) ASSIGN GFile TO * DISP "file saved. . . " DEALLOCATE Array (*)

FOR 1=1 TO Datacount

Short_re(I)=REAL(S22m_short(I)

)

Short_im(I)=IMAG(S22m_short(I)

Open_re (I)=REAL (S22m_open (I)

)

Open_im(I)=IMAG(S22m_open(I)

)

Loaci_re(I)=REAL(S22m_load(I) ) Load_im(I)=IMAG(S22m_load(I)

Thru_re(I)=REAL(S12m_thru{I)

)

Thru_im(I)=IMAG(S12m_thru(I)

Isol_re(I)=REAL(S12m_isol(I)

Isol_im(I)=IMAG(S12m_isol(I)

Rev_re(I)=REAL(S12m_rev(I)

)

Rev_im(I)=IMAG(S12m_rev(I)

NEXT I OFF KEY

CLEAR SCREEN

ALLOCATE Array (Datacount, 7, 2)

FOR 1=1 TO Datacount

Array(I,l,l)=Freq(I)

Array (I, 2, l)=Short_re (I) Array (1,2,2) =Short_im ( I

)

Array (1,3,1) =Open_re ( I

)

Array (1,3,2) =Open_im ( I

)

Array ( I , 4 , 1

) =Load_re ( I

)

Array (1,4,2) =Load_im ( I

)

Array (1,5,1) =Thru_re ( I

)

Array (1,5,2) =Thru_im ( I

)

Array (I, 6,l)=Rev_re(I)

Array (I, 6 , 2

) =Rev_im ( I

)

Array (1,7, l)=Isol_re (I)

Array(I,7,2)=Isol_im(I)

NEXT I Diskdrive$="c: \jones\programs\"

DISP "Please enter a filename for the standards on port 2 (<=30 chars.)

LINPUT Filenaine$

WAIT 1.2

Path$=Diskdrive$&Filename$

CREATE Path$,0

ASSIGN @File TO Path$; FORMAT ON

DISP "Saving File. ,

. "; Path$

OUTPUT 0File;Start_freq

OUTPUT @File;Stop_freq

OUTPUT GFile; Datacount

OUTPUT @ File ;Ar ray (*) ASSIGN @File TO * DISP "file saved. . . " DEALLOCATE Array (*) Done=l

RETURN

50
2058 ! 2060 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

2062 • 2064 End_program:

!

2066 CLEAR SCREEN

2068 DISP "Program has ended..."

2070 END

2072 ! 2074 !/////////////////////////////////////////////////////////////////

2076 SOB Interpolate (Xa(*),Ya(*),N,X,Y)

2078 Init_com: ! 2080 Init_const: ! 2082 Ninax=10

2084 Init_var: ! 2086 DIM C(IOOO) ,D(1000)

2088 REDIM C(Nmax) ,D(Ninax)

2090 Interpolate: ! 2092 Ns=l

2094 Dif=ABS(X-Xa(l)

)

2096 FOR 1=1 TO N

2098 Dift=ABS(X-Xa(I))

2100 IF (Dift<Dif) THEN

2102 Ns=I

2104 Dif=Dift

2106 END IF

2108 C(I)=Ya(I)

2110 D(I)=Ya{I)

2112 NEXT I 2114 Y=Ya(Ns)

2116 Ns=Ns-l

2118 FOR M=l TO N-1

2120 FOR 1=1 TO N-M

2122 Ho=Xa(I)-X

2124 Hp=Xa(I+M)-X

2126 W=C{I+1)-D(I)

2128 Den=Ho-Hp

2130 IF (Den=0) THEN PAUSE

2132 Den=W/Den

2134 D(I)=Hp*Den

2136 C(I)=Ho*Den

2138 NEXT I 2140 IF (2*Ns<N-M) THEN

2142 Dy=C(Ns+l)

2144 ELSE

2146 Dy=D(Ns)

2148 Ns=Ns-l

2150 END IF

2152 Y=Y+Dy

2154 NEXT M

2156 SUBEND

51

*U.S. GPO 2000-0-573-020/40171

NISTTechnical Publications

Periodical

Journal of Research of the National Institute of Standards and Technology—Reports NIST research

and development in those disciplines of the physical and engineering sciences in which the Institute is active. These include physics, chemistry, engineering, mathematics, and computer sciences. Papers

cover a broad range of subjects, with major emphasis on measurement methodology and the basic

technology 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 annual reports, and

other special publications appropriate to this grouping such as wall charts, pocket cards, and

bibliographies.

Applied Mathematics Series—Mathematical tables, manuals, and studies of special interest to physicists,

engineers, chemists, biologists, mathematicians, computer programmers, and others engaged in scientific and technical work.

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 bi- monthly for NIST by the American Chemical Society (ACS) and the American Institute of Physics (AIP).

Subscriptions, reprints, and supplements are available from ACS, 1155 Sixteenth St., NW, Washington,

DC 20056.

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.

Consumer Information Series—Practical information, based on NIST research and experience, covering

areas of interest to the consumer. Easily understandable language and illustrations provide useful background knowledge for shopping in today's technological marketplace.

Order the above NIST publications from: Superintendent of Documents, Government Printing Office,

Washington, DC 20402.

Order the following NIST publications—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. 1127), and as implemented by Executive Order 11717 (38 FR 12315, dated May 11, 1973) and Part 6 of

Title 15 CFR (Code of Federal Regulations).

NIST Interagency Reports (NISTIR)—A special series of interim or final reports on work performed by

NIST for outside sponsors (both government and non-government). In general, initial distribution is handled by the sponsor; public distribution is by the National Technical Information Service, Springfield,

VA 22161, in paper copy or microfiche form.
U.S. Department of Commerce

National Institute of Standards and Technology

325 Broadway

Boulder, Colorado 80303-3328

Official Business

Penalty for Private Use, $300