Stefano Selleri

Giovanni Toso

Active Antennas for Space Applications

The trend in the conception of future spaceborne
radar remote sensing is clearly toward the use of digital beamforming
techniques. These systems will comprise multiple digital
channels, where the analog-to-digital converter is moved closer to
the antenna. This dispenses the need for analog beam steering
and by this the used of transmit/receive modules for phase and
amplitude control. Digital beam-forming will enable Synthetic
Aperture Radar (SAR) which overcomes the coverage and resolution
limitations applicable to state-of-the-art systems. On the
other hand, new antenna architectures, such as reflectors, already
implemented in communication satellites, are being considered for
SAR applications. An open question is the benefit of combining
digital beam-forming techniques with reflector antennas. The
paper answers this question by comparing the system architecture
and digital beam-forming requirements of a planar and a
reflector antenna SAR. Further elaboration yields the resulting
SAR performance of both systems. This paper considers multiple
novel aspects of digital beam-forming SAR system design, which
jointly flow into the presented system performance.

Marwan Younis

Sigurd Huber

Anton Patyuchenko

Federica Bordoni

Gerhard Krieger

Performance Comparison of Reflector- and Planar-Antenna Based Digital Beam-Forming SAR

The high flexibility and tight accuracy
requirements of today's spaceborne synthetic aperture radar (SAR) systems require
innovative technologies to calibrate and process the SAR
images. To perform accurate pattern correction during
SAR processing, an Antenna Model is used to derive the
multitude of different antenna beams generated by active
antenna steering. The application of such an Antenna
Model could be successfully demonstrated for the
TerraSAR-X mission, launched in 2007. The methodology
and the results of the inorbit verification with an achieved
accuracy of better than <svg style="vertical-align:-1.09097pt;width:30.362499px;" id="M1" height="12.05" version="1.1" viewBox="0 0 30.362499 12.05" width="30.362499"  xmlns="http://www.w3.org/2000/svg">
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		</g>
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</svg>&#x2009;dB is reviewed in this paper
in detail showing its outstanding accuracy.

Markus Bachmann

Marco Schwerdt

Benjamin Br&#228;utigam

Accurate Antenna Pattern Modeling for Phased Array Antennas in SAR Applications&#8212;Demonstration on TerraSAR-X

High data rate communications on the move is fastly becoming a major application area for satellite systems using Ku- and higher frequency bands. The ground terminal antenna used in such systems has a profound impact on the system capabilities and is constrained in many often conflicting ways. 
While simple reflector systems offer the lowest cost solution, there is a widespread need for low profile antennas to minimize the antenna visual signature and to satisfy aesthetic and transportation requirements. It is often considered that the use of such antennas will compromise the system performance.

Martin Shelley

Robert Pearson

Javier Vazquez

Low Profile, Dual-Polarised Antenna for Aeronautical and Land Mobile Satcom

The results obtained in the frame of the ESA activity &#8220;<i>Advanced Antenna Concepts For Aircraft In Flight Entertainment</i>&#8221; are presented. The aim of the activity consists in designing an active antenna able to guarantee the Ku band link between an aircraft and a geostationary satellite in order to provide in flight entertainment services. The transmit-receive antenna generates a single narrow beam to be steered electronically in a half sphere remaining compliant with respect to stringent requirements in terms of pattern shape, polarization alignment, EIRP, G/T, and using customized electronic devices. At the same time, the proposed solution should be competitive in terms of cost and complexity.

Alfredo Catalani

Franco Di Paolo

Marzia Migliorelli

Lino Russo

Piero Angeletti

Ku Band Hemispherical Fully Electronic Antenna for Aircraft in Flight Entertainment

The paper presents the design guidelines for Active SAR Antennas followed for the development of COSMO Sky Med SAR Antenna Subsystem. They have brought to define the antenna architecture, the RF, and electrical requirements for all the antenna RF, digital and power units, taking into account the available technologies and achievable performance. The antenna design is described for what the main subsystems is concerned, such as RF, power, digital, including mechanical and thermal aspects. Finally the paper reports also a brief description of the most recent  development carried out in Canada and in Europe in the last ten years, including the on-going programs.

P. Capece

Active SAR Antennas: Design, Development, and Current Programs


This work presents the advances in the development of two innovative flat array antennas for Ku-band mobile satellite terminals. The first antenna is specifically conceived for double-deck trains to allow a bi-directional high data rate satellite link. The available circular surface (diameter 80&#x2009;cm) integrates both a transmitting and a receiving section, operating in orthogonal linear polarizations. The TX frequency range is fully covered while the RX bandwidth is around 1&#x2009;GHz arbitrarily allocated on the DVB range depending on requirements. The beam is steered in elevation through a phased array architecture not employing costly phase shifters, while the steering in azimuth is mechanical. Active BFNs allow excellent performance in terms of EIRP and G/T, maintaining extremely low profile. High antenna efficiency and low fabrication cost are ensured by the employment of innovative SIW (Substrate Integrated Waveguide) structures. The second antenna, receiving-only, is designed for radio/video streaming services in mobile environment. Full DVB coverage is achieved thanks to cavity-backed patches operating in double linear polarization. Two independent broadband active BFNs allow simultaneous reception of both polarizations with full tracking capabilities and a squintless beam steering from <svg style="vertical-align:-0.17555pt;width:20.200001px;" id="M1" height="11.0375" version="1.1" viewBox="0 0 20.200001 11.0375" width="20.200001"  xmlns="http://www.w3.org/2000/svg">
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			</text>

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			</text>

		</g>
	</g>
</svg> to <svg style="vertical-align:-0.17555pt;width:20.200001px;" id="M2" height="11.1625" version="1.1" viewBox="0 0 20.200001 11.1625" width="20.200001"  xmlns="http://www.w3.org/2000/svg">
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			</text>

		</g>
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</svg> in elevation. A minimum gain of 20&#x2009;dBi and G/T &#x3e;<svg style="vertical-align:-0.17555pt;width:18.65px;" id="M3" height="10.9125" version="1.1" viewBox="0 0 18.65 10.9125" width="18.65"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,10.9125)">
		<g transform="translate(72,-63.27)">
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				<tspan style="font-size: 12.50px; " x="0" y="0">−</tspan>
				<tspan style="font-size: 12.50px; " x="8.5645552" y="0">3</tspan>
			</text>

		</g>
	</g>
</svg>&#x2009;dB/<svg style="vertical-align:-0.0pt;width:15.8625px;" id="M4" height="10.6125" version="1.1" viewBox="0 0 15.8625 10.6125" width="15.8625"  xmlns="http://www.w3.org/2000/svg">
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		<g transform="translate(72,-63.51)">
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			</text>

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				<tspan style="font-size: 12.50px; " x="0" y="0">K</tspan>
			</text>

		</g>
	</g>
</svg> are achieved, while maintaining extremely compact size and flat profile. In the design of both antennas fabrication cost is considered as a driving factor, yet providing high performance with a flat profile and thus resulting in a great commercial potentiality.


Roberto Vincenti Gatti

Luca Marcaccioli

Elisa Sbarra

Roberto Sorrentino

Flat Array Antennas for Ku-Band Mobile Satellite Terminals

Present mobile satellite communication systems use large antennas to provide multiple high-gain beams. Each beam covers a fixed geographic cell on the earth. Spatial frequency reuse is provided by synthesising beams with low-power levels over all cells operating at the same frequency. The performance needs for future systems are steadily increasing, leading to higher-gain requirements, which are met by using larger antennas with narrower beams. So the antenna pointing errors become a significant loss factor. An alternative approach is to abandon the use of fixed beams and dynamically synthesise the beams to optimise the antenna performance in real time. This both increases user gain and lowers cofrequency interference whilst also reducing the effects of pointing errors. Simulations, using the Inmarsat 4 antenna architecture as a test example, show that the spatial isolation performance can be significantly improved by using Dynamic Beam Synthesis.

R. F. E. Guy

Potential Benefits of Dynamic Beam Synthesis to Mobile Satellite Communication, Using the Inmarsat 4 Antenna Architecture as a Test Example

A design procedure for the synthesis of a coupled active antenna oscillator array is presented. Such an array is synthesized by deriving two sets of parameters: the radiators' positions and the oscillators' outputs. The outputs are used to excite the radiators. Minimization of the mean square error between the desired pattern and the resulting one is made. Synthesis starts from an initial array, which is perturbed iteratively by varying simultaneously the element excitations and positions. In the iteration, the first variation of the cost function is set equal to zero. The final array results from the last iteration, where the stopping criteria are met. 
The procedure designs simultaneously both the antenna and the attached coupled oscillator array providing viable solutions. The  second by properly configuring the tuning parameters through the use of closed-form formulas. The resulting arrays are shown to comply with the desired pattern and the nonlinear dynamics thus proving the validity of our method.

Theodoros N. Kaifas

John N. Sahalos

An Iterative Technique for the Synthesis of Active Antenna Oscillator Arrays

A cylindrical dielectric resonator antenna
is proposed as a radiator for an active integrated antenna.
Harmonic tuning, which is the key step in designing active antenna
radiators, is achieved via a combination of shape factor control
over the resonator and insertion of reactive elements in the feed
system. Numerical simulations are carried out in a finite elements
framework and a layout for the complete antenna is proposed,
aimed at compactness for subsequent utilization of the radiator
as an element in an active array for satellite communications.

L. Lucci

G. Manara

P. Nepa

G. Pelosi

S. Selleri

Cylindrical Dielectric Resonator Antennas with Harmonic Control as an Active Antenna Radiator

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<p><em>International Journal of Antennas and Propagation </em>publishes research on the design, analysis, and applications of antennas, along with studies related to the propagation of electromagnetic waves through space, air, and other media.</p>


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<p>Chief Editor, Professor Koziel, engages in research focused on surrogate-based modeling and optimization including space mapping technology for engineering design at Reykjavik University.</p>


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International Journal of Antennas and Propagation publishes research on the design, analysis, and applications of antennas, along with studies related to the propagation of electromagnetic waves through space, air, and other media.

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International Journal of Antennas and Propagation

Active Antennas for Space Applications

Active Antennas for Space Applications

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