James A. Nessel

Glenn Research Center, Cleveland, Ohio

Performance Analysis of a 

NASA Integrated Network Array

NASA/TM—2012-217112

May 2012
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James A. Nessel

Glenn Research Center, Cleveland, Ohio

Performance Analysis of a 

NASA Integrated Network Array

NASA/TM—2012-217112

May 2012

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135
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NASA/TM—2012-217112 iii

Executive Summary

The Space Communications and Navigation (SCaN) Program is planning to integrate its individual 

networks into a unified network which will function as a single entity to provide services to user 

missions. This integrated network architecture is expected to provide SCaN customers with the 

capabilities to seamlessly use any of the available SCaN assets to support their missions and allow the 

SCaN Program to optimize the application of its assets to efficiently meet the collective needs of Agency 

missions. One potential optimal application of these assets, based on this envisioned architecture, is that 

of arraying across network assets to significantly enhance data rates and/or link availabilities.

As such, the goal of this study is to determine if or to what extent inter-network antenna arraying in 

the next generation integrated network architecture will enhance space communications performance, 

particularly with respect to link margin improvement in transmit and receive.

The results presented in this report thus address the following question:

What theoretical performance benefits can be realized by arraying antenna elements within the 

framework of a single integrated NASA network?

The key assumptions made in this preliminary analysis include:

• Utilization of current state-of-practice Deep Space Network (DSN), Near Earth Network (NEN), 

and Space Network (SN) antenna asset limitations (e.g., gain, noise temperature, transmitter 

power).

• Common spectrum usage amongst all antenna assets (X-band frequency used in simulations).

• Line-of-Sight (LOS) links from ground to space assets down to 10° elevation angles.

From the results of the analysis, the following important conclusions addressing theoretical SCaN 

Integrated Network Array performance are derived:

• A full SCaN Integrated Network Array (DSN+NEN+SN) provides no improvement in overall 

receive array performance and marginal improvement in transmit arraying performance, relative 

to DSN arraying alone. In other words, if the DSN element is being utilized in space 

communications, the addition of the NEN and SN elements into a total network array increases 

complexity with no realizable improvement in data rate and link availability.

• Intra-network arraying, on the other hand, provides significant improvement for most to all 

transmit and receive arraying scenarios, relative to the current state of practice of single aperture 

usage. For given orbital scenarios, improvements of a minimum of 3 to 10 dB in G/T and 5 to 

10 dB in EIRP is realizable. All things being equal, this will directly translate to a minimum of 

double to an order of magnitude improvement in data rate capabilities.

Based on these findings, it is recommended that NASA proceed with the network antenna 

arraying concept, but with a focus on a network-centric approach, as opposed to a single 

NASA Integrated Network Array. This will drastically reduce complexity in implementation 

and maximize return on investment for upcoming NASA network upgrades.

NASA/TM—2012-217112 1

Performance Analysis of a NASA Integrated Network Array

James A. Nessel

National Aeronautics and Space Administration

Glenn Research Center

Cleveland, Ohio 44135

1.0 SCaN Network Architecture Evolution

The current NASA space communications architecture, shown pictorially in Figure 1, is comprised of

three operational networks that collectively and effectively provide communications services to supported 

user missions through an amalgam of space-based and ground-based assets:

• Space Network (SN).—Constellation of geosynchronous relays (Tracking and Data Relay 

Satellites [TDRS]) and associated ground systems primarily providing transponder services for 

low Earth orbiting (LEO) spacecraft

• Deep Space Network (DSN).—Large aperture ground stations spaced around the world 

providing continuous coverage of satellites from geosynchronous Earth orbit (GEO) to the edge

of our solar system

• Near Earth Network (NEN).—NASA, commercial, and partner ground stations and integration 

systems providing space communications and tracking services to lunar, orbital and suborbital 

missions

Figure 1.—Pictorial representation of current NASA communications architecture.

1

 1

Space Communications and Integration (SCaN) Integrated Network Architecture Definition Document (ADD) 

Vol. 1 Executive Summary, Rev. 1, January 4, 2010
NASA/TM—2012-217112 2

These networks are each optimized to support user missions in specific operational domains (ranging 

from near Earth to deep space) where the communications and tracking requirements are quite distinct.

Thus, the present architecture is very capable, but is also complex because of the heterogeneous nature of 

the network assets and the lack of consistent service offerings, interfaces, and interoperability. The 

inherent complexity is attributable to the fact that each network, i.e., SN, NEN, and DSN, has been 

evolving independently for as long as four decades on their own respective paths.

The vision for the future SCaN architecture is to build and maintain a scalable and integrated 

infrastructure that provides comprehensive, robust, and cost effective space communications services at 

order-of-magnitude higher data rates to enable NASA's science and exploration missions, as depicted in 

Figure 2. To realize this, the current SCaN networks will evolve into a single integrated network by 

implementing an architecture that includes a consistent suite of international standards, interfaces and 

protocols. While the different operating domains and unique customer needs will still necessitate some 

distinct capabilities, the integrated network will use common crosscutting standards and implementations 

to the greatest extent possible. An integrated network operations and management function will serve as 

the interface for all NASA SCaN network customers, which lends itself to advanced operational 

technologies such as inter-network arraying.

Figure 2.—SCaN Notional Integrated Network Architecture (circa 2025).

1
NASA/TM—2012-217112 3

2.0 SCaN Integrated Network Array

The concept behind the Integrated Network Array is built upon the premise that its realization, though 

relatively complex to implement, would represent the optimal performance of a fully integrated SCaN 

communications system. By arraying all available assets in view of a particular spacecraft, orders of 

magnitude increase in system gain can be readily achieved. And, based upon the requirements determined 

for the future SCaN network architecture, NASA is well-positioned to begin considering the 

implementation of an Integrated Network Array technology development plan and architecture.

The following section provides an analysis of the predicted performance of the SCaN Integrated 

Network Array for receive and transmit applications. Theoretical array performance, in terms of Gain 

over System Temperature ratio (G/T) and Effective Isotropic Radiated Power (EIRP), are derived to lay 

the foundation for a simulated scenario of G/T and EIRP improvement as a function of orbital distance 

and time of day.

2.1 Theoretical Performance of an Integrated Network Array

The approach taken in determining performance benefits of an integrated network arraying 

architecture is to quantify the improvement in the realizable link margin when considering the receive 

array (G/T) and the transmit array scenarios (EIRP). The full derivation of these terms in an array 

environment is provided in Appendices A and B, respectively, and a summary of the pertinent results are 

presented below.

2.1.1 SCaN Integrated Network Array Performance: Assumptions

Line of sight (LOS) visibility analysis using STK simulation software was performed for an arbitrary 

equatorial orbiting spacecraft at various orbital distances (see Appendix F). Though these quantitative 

results are limited to this particular scenario (due to the specific geometry), the general conclusions 

derived from this analysis are applicable to all arraying situations, since the arraying process is 

unchanged. 

All simulations performed herein are conducted under the following assumptions:

• Utilization of current Deep Space Network (DSN), Near Earth Network (NEN), and Space 

Network (SN) antenna asset limitations (in terms of gain, system noise temperature, transmitter 

power). A summary of these parameters for each DSN, NEN, and SN antenna is provided in 

Appendices C, D, and E, respectively.

• Common spectrum usage amongst all antenna assets (X-band operational frequency: 8.4 GHz).

• LOS links from ground to space assets down to minimum 10° elevation angles.

• Omni-directional antenna at spacecraft.

• Satellite orbit at Earth equatorial plane from low Earth orbit (LEO) to lunar orbital distances.

• Only consider ground station antennas of diameter >10-m (smaller aperture antennas contribute 

marginal improvement in array performance).

• Include the potential use of SN ground segment antennas for receive/transmit arraying2

.

2.1.2 SCaN Integrated Network Array Performance: Receive Array

For a receive arraying scenario, the fundamental figure of merit in determining array sensitivity is a 

large G/T. For an array of N antennas, each with individual antenna element gain, Gi, and system noise 

temperature, Ti, the improvement in arraying gain is given by,

 2

Note: this scenario is likely not realizable in the future SCaN Integrated Network architecture, but included in the 

simulation to determine if impact on array performance is significant.
NASA/TM—2012-217112 4

G

T

�

array

= �∑ αi�Gi

N

i=1 �

2

∑ αi

2TiN

i=1 + TB_eff

(2.1)

where αi is the individual element amplitude weighting factor (whose optimal value is derived in 

Appendix A), and TB_eff is the correlated effective sky brightness temperature common to the array 

elements. From this relationship, several intuitive conclusions can be drawn regarding the sensitivity of a 

large array. Considering a simplistic case in which all the antenna elements are identical in gain and

system noise temperature, the arraying G/T, with optimal weights, can be simplified to

G

T

�

array

= N �

G

T

� (2.2)

A plot of the improvement in array G/T as a function of the number of identical elements added to the 

array is shown in Figure 3. From Figure 3, it is obvious that as we continue to add more elements, the 

improvement in the G/T of the array, relative to a single element, is marginalized rather quickly, due to 

the linear function of array size. In fact, by the time the array has grown to 10 elements, the enhancement 

in G/T by an additional element is only 0.4 dB. Keep in mind that this is for the case of 10 identical

elements. For elements of varying aperture size and system noise temperature, this improvement will be 

dominated by the most sensitive receiver and the addition of less sensitive elements will have little to no 

effect. This was evident in the results of the simulation for the SCaN Integrated Network Array 

performance discussed below.

Appendix F provides the STK results for individual ground station visibility of an equatorial orbiting 

spacecraft at various orbital distances throughout a 24 hr period. Figure 4 shows the resulting SCaN 

Integrated Network Array G/T performance for spacecraft orbits from LEO (1,000 km) to extra-lunar

orbit (500,000 km) at a fixed reference time, 16:00 UTC. Figure 5 shows the G/T improvement over the 

course of the full 24-hr period for a fixed sub-lunar orbit (200,000 km), relative to single aperture DSN or 

NEN coverage.

Figure 3.—Plot of incremental improvement in array G/T performance as more identical elements 

are added to an antenna array. Improvement is relative to a single antenna element.

0

2

4

6

8

10

12

14

0 2 4 6 8 10 12 14 16 18 20

Incremental Improvement in Array G/T (dB)

Number of Antenna Elements

Array G/T Improvement vs. Array Size
NASA/TM—2012-217112 5

Figure 4.—SCaN Integrated Network Array G/T performance for varying equatorial orbits.

Simulation time reference is fixed at 16:00 UTC. Array element labels can be referenced 

in Appendices C to E.

Figure 5.—SCaN Integrated Network Array G/T performance for a 200,000 km orbit over a 

24-hr period.

Several key conclusions can be derived from the results of these figures:

1. As orbital distance is increased from LEO orbit to beyond lunar orbit, the availability of visible 

NASA ground station assets increases. For this particular scenario, a maximum of 27 NASA 

ground station communications assets become visible to an equatorial orbiting spacecraft (at time 

reference, 16:00 UTC with a duration of 1 hr).
NASA/TM—2012-217112 6

2. Total SCaN Integrated Network Array G/T performance (solid blue line) is dominated by the G/T 

of the DSN elements of the array (solid red line). In other words, addition of the NEN and SN 

ground station elements in the total array performance provides no improvement in total array 

performance. This is consistent with expected results, as the DSN antenna elements are 

significantly more sensitive than either of the NEN or SN antennas.

3. Within a given network (i.e., the DSN array, NEN array, or the combined NEN+SN array), array 

G/T performance is significantly enhanced over the state-of-practice use of a single antenna 

element.

○ Arraying of all Canberra DSN assets (two 34-m and one 70-m antenna) indicates an 

approximate 10-dB improvement in G/T relative to a single 34-m DSN antenna (dashed blue 

line), but only a 1-dB improvement in G/T relative to a single 70-m DSN antenna (not shown 

in figure).

○ For periods of time when multiple DSN sites are in view of a spacecraft (i.e., Canberra and

Goldstone for 0.5 to 1 hr in this particular scenario), DSN arraying improves G/T by more 

than 20 dB relative to a single 34-m DSN antenna, or a 12-dB improvement relative to a 

single 70-m DSN antenna.

○ NEN arraying (solid orange line) can provide 3 to 10 dB improvement in G/T over the stateof-practice implementation of a single 13-m aperture antenna (dotted purple line).

○ For an integrated NEN+SN ground station array (solid green line), an additional 3-dB 

improvement in G/T over solely NEN arraying is realizable for most orbital arrangements.

4. For a given day, DSN arraying improves G/T by a minimum of 10 dB relative to a single 34-m 

aperture antenna, while NEN arraying provides an approximate 5 dB improvement over state of 

practice. Integrating an NEN+SN array provides a maximum 3 dB excess margin.

2.1.3 SCaN Integrated Network Array Performance: Transmit Array

In a transmit arraying scenario, the fundamental figure of merit in determining array performance is 

the EIRP. For an array of N antennas, each with individual antenna element gain, Gn, and transmit power, 

Pm, the total array EIRP is given by the product of the sums of the individual antenna element gains and 

transmit powers (see Appendix B for full derivation).

EIRParray = Garray � Pm

N

m=1

= ��Gn

N

n=1

��� Pm

N

m=1

� (2.3)

Let us consider the simple case of an array of N identical antenna elements, each transmitting the same 

power, P. This assumption gives us the well-known N2 improvement in EIRP due to coherent arraying.

EIRParray = N2GP (2.4)

A plot of the incremental improvement in EIRP as more elements are added to an array demonstrates 

the dramatic enhancements possible (see Figure 6). Though theoretically possible to increase without 

bound, the improvement in EIRP due to additional antenna elements begins to show marginal 

improvement at 20 elements, only adding approximately 0.4 dB/element as the array size increases 

beyond this point. This is inherently due to the square law relationship with array size. Further, for nonidentical elements in an array, the increase in EIRP will be dominated by the largest individual EIRP 

contributors. Compared to the receive scenario derived above, uplink arraying provides much larger 

improvements in array performance, due to the N2 relation to array size.

For the same scenarios described in the receive case, the transmit case is now investigated. Figure 7 

shows the improvement in arraying EIRP at the same reference time, 16:00 UTC, for various orbits. 

Figure 8 shows the improvement in arraying EIRP at a fixed sub-lunar orbit of 200,000 km over the 

course of 24 hr. Notice, from Figure 7, that integrating the NEN+SN array together provides a much more 
NASA/TM—2012-217112 7

drastic increase in array performance, relative to the NEN ONLY array. This is primarily due to the fact 

that the transmit powers of the SN ground segment provides an additional 3 kW of power/antenna 

element, which is much larger than currently available in the NEN infrastructure.

Figure 6.—Plot of incremental improvement in array EIRP performance as more identical elements 

are added to an antenna array. Improvement is relative to a single antenna element.

Figure 7.—SCaN Integrated Network Array EIRP performance for varying equatorial orbits.

Simulation time reference is fixed at 16:00 UTC. Array element labels can be referenced in 

Appendices C to E.
NASA/TM—2012-217112 8

Figure 8.—SCaN Integrated Network Array EIRP performance for a 200,000 km orbit over a 24-hr period.

The key conclusions to be drawn from this analysis are as follows:

1. Total SCaN Integrated Network Array EIRP performance is dominated by the DSN array EIRP, 

as these elements possess the highest gain and transmitter power/element. However, the 

contribution of NEN and SN arraying is apparent, though marginalized to less than 2 dB for 

extra-lunar orbits.

2. Within a given network (i.e., the DSN array, NEN array, or the combined NEN+SN array), array 

EIRP performance is significantly enhanced over the state-of-practice use of a single antenna 

element.

○ Arraying of all Canberra DSN assets (two 34-m and one 70-m antenna) indicates an 

approximate 10-dB improvement in EIRP relative to a single 34-m DSN antenna (dashed 

blue line), and a 5-dB improvement in EIRP relative to a single 70-m DSN antenna (not 

shown in figure).

○ For periods of time when multiple DSN sites are in view of a spacecraft (i.e., Canberra and 

Goldstone), DSN arraying improves EIRP by more than 20 dB relative to a single 34-m DSN 

antenna, or a 15-dB improvement relative to a single 70-m DSN antenna.

○ NEN arraying (solid orange line) can provide 20 to 30 dB improvement in EIRP over the 

state-of-practice implementation of a single 13-m aperture antenna with 500W transmitter 

power (dotted purple line).

○ For an integrated NEN+SN ground station array (solid green line), an additional 6 to 8 dB 

improvement in EIRP over solely NEN arraying is realizable for most orbital arrangements.

3. Over the course of a 24-hr period for an equatorial sub-lunar orbit (200,000 km), network-centric 

arraying provides 10 to 15 dB improvement in EIRP link margin.

3.0 Conclusions

Utilizing arraying technology for the future SCaN Integrated Network architecture represents an 

optimal realization of NASA communications resources. However, several implementation and return on 

investment issues arise when considering the development of a fully integrated SCaN Network Array:
NASA/TM—2012-217112 9

• Implementation of a SCaN Integrated Network Array will require spectrum sharing, or some form 

of adaptable common spectrum use, to realize cross-network arraying. This implementation is 

currently not being considered in the development of the next generation SCaN Integrated 

Network and would require some modification to the current development plan.

• More importantly, arraying the DSN element with either of the NEN or SN elements provides no 

improvement in receive array performance and only marginal improvements (< 2 dB excess 

margin) in transmit array performance. Therefore, implementation of this approach should not 

be furthered.

Based on these results, it is determined that the best way to proceed in implementing an arraying 

technology development plan and architecture is to focus on network-centric arraying. This 

implementation plan would provide the most straightforward and optimal return on investment strategy 

for realizing receive/transmit arraying for the NASA’s communications infrastructure.

• A network-centric implementation will be straightforward since arraying technology is already 

being developed along this path within the various networks. Further, common spectrum use 

required for coherent arraying are already resolved within individual networks.

• Network-centric arraying can provide substantial improvement in receive and transmit arraying 

relative to the current state of practice of single aperture implementation. The return on 

investment under this approach is significantly greater than implementing a fully integrated SCaN 

network array.

NASA/TM—2012-217112 11

Appendix A.—Derivation of Array G/T

Let us consider an array of N antennas, each characterized by a gain, Gi, and a system temperature, Ti.

Let us further assume that the phasing amongst antenna elements are perfectly matched to maximize the 

signal to noise ratio (SNR) of the receive arrayed signal in the direction of the incident narrowband signal 

via appropriate phase compensation and weighting and that the arraying is performed at some baseband 

frequency, f. For the given antenna assets in view of a particular spacecraft at some time, t, the summed 

voltage signal at baseband can therefore be described by,

varray(f,t) = �αie−jφivi(f,t + τi)

N

i=1

(A.1)

where N is the number of arrayed antennas in view of the spacecraft, vi is the baseband voltage at the 

receiver, τi is the geometrical phase delay of the array elements in the direction of propagation, and αie

–jφi

is the complex amplitude and phase weighting factor applied to each individual antenna. From the 

definition of power, the arrayed receive power is related to the summed array voltages by,

Parray = 〈� �varray(f,t)�

2

df

∆f

0

〉

= 〈� �varray(f,t)��varray

∗ (f,t)�df

∆f

0

〉

= 〈� ��αie−jφivi(f,t + τi)

N

i=1

���αkejφkvk

∗(f,t + τk)

N

k=1

� df

∆f

0

〉

= 〈� ��αi

2|vi(f,t + τi)|

2

N

i=1

+��αiαke−jφi

+jφkvi(f,t + τi)vk∗(f,t + τk)

N

k=1

i≠k

N

i=1

� df

∆f

0

〉

(A.2a)

(A.2b)

(A.2c)

(A.2d)

= �αi

2Pi

N

i=1

+��αiαkρik

N

k=1

i≠k

N

i=1

(A.2e)

where <...> denotes the time average, and Pi is the single dish power from the i

th antenna given by,

Pi = 〈� df|vi(f,t + τi)|

2

∆f

0

〉 (A.3)

and ρik is the unnormalized correlation between the i

th and kth antennas described by,

ρik = 〈� e−jφi+jφkvi(f,t + τi)vk

∗(f,t + τk)df

∆f

0

〉 (A.4)

Since the arrayed power consists of an arrayed signal power and an arrayed noise power, we can derive 

the following expressions for each based on the above equations.
NASA/TM—2012-217112 12

Parray

signal = �αi

2Pi

signal

N

i=1

+��αiαkρik

signal

N

k=1

i≠k

N

i=1

(A.5)

Parray

noise = �αi

2Pinoise

N

i=1

+��αiαkρik

noise

N

k=1

i≠k

N

i=1

(A.6)

Parray

noise ≈ �αi

2Pinoise

N

i=1

(A.7)

where we have noted that the arrayed noise power is accurately approximated by the sum of the weighted 

individual element noise powers, due to the fact that uncorrelated noise will be present in each signal path 

due to the large separation distance of each antenna element.

Therefore, the output array G/T can be related to the array output SNR by,

G

T

�

array

∝

Parray

signal

Parray

noise =

∑ αi

2PiN signal

i=1 + ∑ ∑ αiαkρik

N signal

k=1

i≠k

N

i=1

∑ αi

2PiN noise

i=1

(A.8)

To determine a final expression for array G/T, we can relate the receive signal power, the cross-correlated 

signal power component, and the noise power to the antenna gain and system temperatures (ignoring any 

path loss contributions and assuming maximal phasing conditions) by,

Pi

signal ≡ PtxGi (A.9)

ρik

signal ≡ �PtxGi�PtxGk = Ptx�GiGk (A.10)

Pi

noise ≡ kBTi∆f (A.11)

where kB is Boltzmann’s constant, Ptx is the transmit power from, i.e., the spacecraft, Gi is the individual 

antenna system gain, Ti is the individual antenna system temperature, and Δf is the bandwidth at the 

output of the beamformer. Thus, the G/T for an array as a function of individual antenna element gain and 

system temperature is,

G

Tarray

=

∑ αi

2GiN

i=1 + ∑ ∑ αiαk�GiGk

N

k=1

i≠k

N

i=1

∑ αi

2TiN

i=1 + TB_eff

= �∑ αi�Gi

N

i=1 �

2

∑ αi

2TiN

i=1 + TB_eff

(A.12)

where the term, TB_eff has been introduced to account for the correlated system noise temperature 

potentially “seen” in common by the antenna elements, as contributed by the atmospheric brightness 

temperature. For the case of completely uncorrelated noise contributions (very far apart antenna 

elements), let us presume that the effective brightness temperature contribution is minimal. Thus, to 

ensure optimal combining of the receive signal, the weighting factors, αi, should be chosen so as to 

maximize the array G/T. Such αi will satisfy the equation:
NASA/TM—2012-217112 13

d(G⁄T)

dαj

= 0 (A.13)

d(G⁄T)

dαj

=

2αjGj + 2 ∑ αk�GjGk

N

k=1

k≠j

∑ αi

2TiN

i=1

−

2αjTj �∑ αi

2GiN

i=1 + ∑ ∑ αiαk�GiGk

N

k=1

i≠k

N

i=1 �

�∑ αi

2TiN

i=1 �

2 (A.14)

=

�∑ αi

2TiN

i=1 � �2αjGj + 2 ∑ αk�GjGk

N

k=1

k≠j

� − 2αjTj �∑ αi

2GiN

i=1 + ∑ ∑ αiαk�GiGk

N

k=1

i≠k

N

i=1 �

�∑ αi

2TiN

i=1 �

2

(A.15)

The above equation will equal zero when the numerator is equal to zero. Thus,

0 = �αi

2Ti

N

i=1 ⎝

⎛2αjGj + 2�αk�GjGk

N

k=1

k≠j ⎠

⎞ − 2αjTj ��αi

2Gi

N

i=1

+��αiαk�GiGk

N

k=1

i≠k

N

i=1

� (A.16)

Solving the N equations for N unknowns, it can be shown that the optimal weights for maximum array 

G/T is determined to be,

αi = �Gi

Ti

(A.17)

Note that in the case of correlated atmospheric brightness temperature contribution (i.e., for the case of 

antenna elements located in approximately the same geophysical location), the optimal weight calculation 

will be biased by some amount. However, it has been shown that this contribution produces an error of 

approximately 10% in the optimal weight determination which can be considered negligible for the 

purposes of this analysis.

3

 3

R. Dewey, “The Effects of Correlated Noise in Intra-Complex DSN Arrays for S-Band Galileo Telemetry 

Reception,” TDA Progress Report 42-111, November 15, 1992.

NASA/TM—2012-217112 15

Appendix B.—Derivation of Array EIRP

From the transmitted power perspective, in the optimal case, we know that for a widely distributed 

array, the maximum achievable arraying gain, Garray, is given simply by the sum of the individual antenna 

gains, Gn.

E�⃗

array(r, θ, φ) = �

e−jkR

2πR � ��Cmejφm�fm(θ, φ)e−jka�r ∙ρ��⃗m

N

m=1

(B.1)

where, k is the wavenumber (2π/λ), fm(θ,φ) is the individual antenna voltage pattern, 

The array radiation intensity is described by, 

U(θ,φ) = r2

2η

�E�⃗

array(r, θ, φ)�

2 (B.2)

= k2

8π2η� �fm(θ, φ)fn(θ, φ)∗ej(φm−φn)

N

n=1

N

m=1

(B.3)

The total radiated power for an array with elements spaced vary far apart (d >> λ) is approximated by

Prad = � � U(θ, φ) sin θ dθdφ

π/2

0

2π

0

(B.4)

= πk2

η � ��|fm(θ, φ)|

2

N

m=1

�sin θ dθ

π/2

0

(B.5)

If, for analytical simplicity, we assume that no blockage occurs and that the reflectors are uniformly 

illuminated by a linearly polarized feed, and the inter-element phasing is such that the peak of the array 

pattern is directed to zenith, the antenna element field pattern of a circular aperture can be described by,

fm(θ, φ) = jkεm �2πam

2 J1(kam sin θ)

kam sin θ � (B.6)

where am is the reflector antenna diameter, εm is the individual antenna efficiency, and J1 is the Bessel 

function of first order. From this assumption, the array gain can readily be determined as,

U0 ≡ U(θ = 0) = k2

8η� �am

2 an2

N

n=1

N

m=1

(B.7)

Prad = π

2η� am

2

N

m=1

(B.8)

Garray = 4πU0

Prad

= 4π2

λ

2 �an

2

N

n=1

= �Gn

N

n=1

(B.9)
NASA/TM—2012-217112 16

where it is observed that the total array gain simplifies to the sum of the individual antenna element gains 

for a widely distributed array. This solution is valid for any arbitrary array in which the separation 

distance between elements is much greater than the wavelength of operation.

The total transmit power is given simply by the sum of the individual element transmit powers (Pm).

Therefore the optimally combined array EIRP is easily defined as:

EIRParray = Garray � Pm

N

m=1

= ��Gn

N

n=1

��� Pm

N

m=1

� (B.10)

Note that for an array of identical antenna elements with equal transmit powers, we obtain the wellknown improvement in array EIRP as N2 times the individual antenna element EIRP. However, for an 

array of dissimilar antenna elements, this maximal improvement is weighted by the relative levels of each 

individual element, as will be shown in the results of the integrated network array.
NASA/TM—2012-217112 17

Appendix C.—State-of-Practice DSN Antenna Specifications4

 4 JPL 810-005 Handbook

NASA/TM—2012-217112 19

Appendix D.—State-of-Practice NEN Antenna Specifications5

 5

B. Golden, SCaN “As-Is” Architecture Description Document

NASA/TM—2012-217112 21

Appendix E.—State-of-Practice SN Ground Segment Antenna Specifications5

NASA/TM—2012-217112 23

Appendix F.—Simulated Ground Segment Visibilities to Spacecraft (STK)

The following STK plots indicate ground station LOS availability for an equatorial orbiting spacecraft 

at various distances from Earth. The diagram below depicts how these plots are to be interpreted. The 

reader must refer back to Appendices C to E to identify the particular antenna assets being arrayed.

Antenna Aperture Size

16:00 UTC Reference 

Time of Simulation

Simulation Run Time Simulated Orbital 

Distance

Antenna Asset ID

(see Appendices C to E)
NASA/TM—2012-217112 24
NASA/TM—2012-217112 25
NASA/TM—2012-217112 26
NASA/TM—2012-217112 27
NASA/TM—2012-217112 28
NASA/TM—2012-217112 29
NASA/TM—2012-217112 30
NASA/TM—2012-217112 31
NASA/TM—2012-217112 32

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Performance Analysis of a NASA Integrated Network Array 

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14. ABSTRACT

The Space Communications and Navigation (SCaN) Program is planning to integrate its individual networks into a unified network which 

will function as a single entity to provide services to user missions. This integrated network architecture is expected to provide SCaN 

customers with the capabilities to seamlessly use any of the available SCaN assets to support their missions to efficiently meet the collective 

needs of Agency missions. One potential optimal application of these assets, based on this envisioned architecture, is that of arraying across 

existing networks to significantly enhance data rates and/or link availabilities. As such, this document provides an analysis of the transmit 

and receive performance of a proposed SCaN inter-network antenna array. From the study, it is determined that a fully integrated internetwork array does not provide any significant advantage over an intra-network array, one in which the assets of an individual network are 

arrayed for enhanced performance. Therefore, it is the recommendation of this study that NASA proceed with an arraying concept, with a 

fundamental focus on a network-centric arraying. 

15. SUBJECT TERMS

Array; Deep space network; Near Earth network; Space network 

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