Presentation on "Integration of Microwave Filters in Active Array Antennas for Space Applications" at the International Workshop on Microwave Filters, CNES, Toulouse, 23-25/03/2015

1. ESA UNCLASSIFIED - For Official Use
Integration of Microwave Filters
in Active Array Antennas for
Space Applications
Dr. Piero Angeletti, Dr. ing. Marco Lisi
International Workshop on Microwave Filters
CNES, Toulouse, 23-25/03/2015

2. P. Angeletti – M. Lisi | 24/03/2015 | Slide 2
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Summary
• Active array antennas for space applications
require a wide range of state-of-the-art
technologies and a large number of passive and
active electronic equipment;
• Filters play an essential role both in terms of their
impact on the overall payload performance and in
the perspective of mass and cost reduction;
• A system engineering approach to the design and
development of active arrays (specifically to the
definition of filtering requirements) is mandatory
in order to achieve a synergic and effective
integration of all functions.

3. P. Angeletti – M. Lisi | 24/03/2015 | Slide 3
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Direct Radiating Array (DRA)
Active Antenna Configuration

4. P. Angeletti – M. Lisi | 24/03/2015 | Slide 4
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Array Fed Reflector (AFR)
Active Antenna Configuration

5. P. Angeletti – M. Lisi | 24/03/2015 | Slide 5
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Input (Rx) Filter
Fundamental Functions
1.To suppress the leakage from the
transmit section of the same payload as
well as all other out-of-band signals
(carriers and intermodulations)
generated on-board;
2.To reduce the overall out-of-band noise
received by the antenna and otherwise
reaching the LNA input.

6. P. Angeletti – M. Lisi | 24/03/2015 | Slide 6
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Artemis S-Band DRA Input
Filter
Measured response
of an S-band DRA
input filter
(Artemis Multiple
Access Data Relay
Payload Study),
showing a higher
than 70 dB
rejection at Tx
frequencies (L and
S bands).

7. P. Angeletti – M. Lisi | 24/03/2015 | Slide 7
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Output (Tx) Filter
Fundamental Functions
1.Reduce the noise transmitted at the Rx
frequency of the same payload;
2.Reduce noise and intermodulation
products at the receive frequencies of
other payloads on-board the satellite;
3.Reduce noise and intermodulation
products transmitted to ground over
protected frequency bands (e.g. radio
astronomy bands).

8. P. Angeletti – M. Lisi | 24/03/2015 | Slide 8
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Why to Optimize Filters
Requirements?
• In a traditional payload one or a few input filters are
needed in the receive section, while one or a few
output filters or multiplexers (OMUX’s) are present in
the transmit section;
• In active antennas as many input filters and output
filters as the number N of feed elements are needed,
where N can be as high as several tens or even
several hundreds of units;
• Optimizing filters requirements means minimizing
complexity, mass and cost of the payload;
• It is worth noting that, while electronic devices lend
themselves to miniaturization, electromagnetic
structures (such as microwave filters) are strongly
constrained by the laws of physics (e.g. wavelength,
current densities, conductivity, Q-factor).

9. P. Angeletti – M. Lisi | 24/03/2015 | Slide 9
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Main Characteristicis of Filters
Integrated in Active Antennas
• Insertion loss;
• Out-of-band rejection;
• VSWR (a high VSWR, besides introducing reflection
losses, would also cause in-band amplitude and phase
ripples);
• Phase tracking (over temperature and ageing);
• Power handling;
• Passive intermodulation (PIM) products;
• Multipactoring (not likely in active antennas, as each
transmit filter is handling a somehow limited RF
power level, as compared to a traditional payload
configuration);
• Size;
• Mass.

10. P. Angeletti – M. Lisi | 24/03/2015 | Slide 10
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Insertion Loss Always Plays an
Essential Role
• Pass-band loss (insertion loss) is
important in both Rx and Tx filters;
• In a receive filter, the insertion loss will
add to the Noise Figure of the low-noise
amplifier degrading the overall payload
G/T;
• In the transmit filter, a higher insertion
loss would mean tougher power
amplifier specs, higher power
consumption and more heat dissipation.

11. P. Angeletti – M. Lisi | 24/03/2015 | Slide 11
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Amplitude and Phase Tracking
Requirements
• An accurate phase (amplitude) tracking is required
between any two chains in the active antenna, at all
operating temperatures and over the entire life time;
• Two kinds of errors can be identified: "systematic"
errors and "random" errors;
• Systematic errors are defined as predictable and/or
measurable deviations of the absolute insertion phase
(or absolute amplitude) of an active chain from its
nominal value at reference conditions, i.e. at
reference temperature (e.g. ambient) and at beginning
of life;
• Systematic errors can be easily calibrated out;
• Random errors derive mainly from temperature and
aging effects, adding to systematic errors.

12. P. Angeletti – M. Lisi | 24/03/2015 | Slide 12
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Systemic Definition of
Filtering Requirements (1/3)
Factors to be considered in a Rx active antenna
design:
• The out-of-band performance of the radiating
elements (both conducted, e.g. return loss, and
radiated, i.e. pattern);
• The optimal apportionment between filtering at
RF and filtering at IF;

13. P. Angeletti – M. Lisi | 24/03/2015 | Slide 13
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Systemic Definition of
Filtering Requirements (2/3)
• Apportionment of the required overall filter
response, in an analogue beam-forming antenna,
having filters at the M outputs of the BFN (N,
number of feeds, is usually much higher than M,
number of beams);
• The spatial isolation between RX and TX
antennas of the same payload and between
antennas of different payloads on-board the
satellite.

14. P. Angeletti – M. Lisi | 24/03/2015 | Slide 14
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Systemic Definition of
Filtering Requirements (3/3)
Factors to be considered in a Tx active antenna
design:
• spatial isolation w.r.t. other antennas on-board
the spacecraft;
• “filtering” effect deriving from the
intermodulation products being radiated with
radiation patterns far different from that of the
TX carrier. This dispersion effect derives from a
linear combination of the amplitude and phase
excitation coefficients, according to the order of
the intermodulation.

15. P. Angeletti – M. Lisi | 24/03/2015 | Slide 15
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Artemis S-Band Active
Antenna (Feasibility Study)

16. P. Angeletti – M. Lisi | 24/03/2015 | Slide 16
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Globalstar 1st Gen S-Band Tx
Active Antenna

17. P. Angeletti – M. Lisi | 24/03/2015 | Slide 17
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Ka-Band “Transmit Multibeam
Antenna (TXMBA)”
Astrium Casa Espacio

18. P. Angeletti – M. Lisi | 24/03/2015 | Slide 18
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Ceramic 3D Stereolithography
Technology
Université de Limoges/CNRS

19. P. Angeletti – M. Lisi | 24/03/2015 | Slide 19
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Substrate Integrated
Waveguide (SIW) Technology

20. P. Angeletti – M. Lisi | 24/03/2015 | Slide 20
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Conclusion
• Filters are among the most challenging components
in the realization of active array antennas for space
applications;
• More efforts are required in terms of new
technologies and of a better integration with active
components (LNA’s and SSPA’s);
• The final objective is making active antennas highly
performing and truly affordable, with drastic
improvements in terms of complexity, size, mass and
cost;
• A systemic approach is mandatory to the purpose of
best matching the overall architecture to physical and
technological constraints.

21. P. Angeletti – M. Lisi | 24/03/2015 | Slide 21
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