The paper describes a deterministic algorithm based on simple analytical equations for designing planar circular sparse array antennas where the positions and the dimensions of the radiating elements are jointly exploited and optimized. The proposed solution permits addressing one of the main limitations associated to sparse arrays, i.e., their poor aperture efficiency especially when patterns with low sidelobe levels are obtained using only the density of the elements avoiding any amplitude tapering. The accuracy of the method is guaranteed by the fact that the achieved directivity differs from the target value, associated to a continuous reference aperture distribution, by a quantity asymptotically equal to the factor π/4 (corresponding to about -1.05 dB) representing the filling factor of a circular planar array organized in concentric rings populated by circular apertures. As required for several applications, the method includes the possibility to add a constraint on the maximum scanning angle with respect to the boresight direction.

Array Antennas With Jointly Optimized Elements Positions and Dimensions Part II: Planar Circular Arrays

Since their conception satellites have offered the promise of more capacity for terrestrial communication systems or to exploit their inherent multicasting and broadcasting capabilities. Recent advances in satellite technology have resulted in the integration of satellite and terrestrial networks to meet the quality and capacity requirements of modern day communication systems. Network and Protocol Architectures for Future Satellite Systems reviews the emerging technologies being deployed in the networking architectures being proposed in the framework of the Future Internet. Novel protocols such as Multi Path TCP (MPTCP) and networking trends such as Information Centric Networking (ICN) are described in depth and their application in segments deploying both satellite and terrestrial networks are illustrated. This is also the first monograph to review content-based networking extensively. This is becoming increasingly important driven by the ubiquitous nature of the internet. Applications to satellite communications are illustrated and the technical challenges to be further addressed are highlighted.

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Network and Protocol Architectures for Future Satellite Systems

We propose a new architecture for array antennas able to achieve a high-gain performance by using a low number of elements and uniform-amplitude excitations. The solution is realized through a fast and deterministic design technique able to accurately emulate, by exploiting only the feeds' size as degree of freedom of the synthesis, 'ideal' continuous aperture sources fulfllling at best the assigned directivity requirements. The given theory is supported by numerical examples concerning the synthesis of isophoric direct radiating arrays devoted to a multibeam coverage of Europe from a geostationary satellite.

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Isophoric Array Antennas with a Low Number of Control Points: a `Size Tapered' Solution

This paper presents the results of the development of an active phased array antenna for Ku-Band Receive-only mobile satellite communications realised within the ESA-project NATALIA. The phased array antenna is designed for mobile satellite services and dedicated for automotive applications. An overview of the complete build-up will be provided as well as the current status of the multilayer Printed Circuit Board (PCB) designed for mass production and a dedicated MMIC-component responsible for the beam steering of the array. Finally, the results of the measurements of a proof-of-concept breadboard performed to validate the antenna will be illustrated.

Low cost Ku-band electronic steerable array antenna for mobile satellite communications

The aim of the paper is to provide an overview on the activities recently promoted by the European Space Agency (ESA) on satellite multibeam antennas based on phased arrays. The attention is focused on antennas generating multiple spot beams coverages with a single main aperture. In particular, solutions based on direct radiating arrays, active discrete lenses, and confocal reflectors will be discussed. These solutions present some challenges but also some advantages as compared to conventional architectures based on multi reflectors with a single feed per beam. ESA is supporting since several years activities in this challenging domain.

Multibeam antennas based on phased arrays: An overview on recent ESA developments

Sparse arrays for satellite communications: from optimal design to realization

Due to the continuous growth of satellite communications and the nearly saturation of the Ku band, Ka band has started to be used for broadband communications. For the new generation of spaceborne antennas operating in Ka band, satellite communication operators require some in-orbit features as the flexibility and the re-configurability. The most suitable antenna configuration candidate to provide these characteristics is the Active Direct Radiating Array. This paper describes innovative solutions that, by the use of sparse/thinned lattices, allows to minimize the radiating elements number reducing the complexity for the cooling system integration (e.g. heat-pipes) and beam former implementation.

Ka-Band active sparse arrays for SATCOM applications

This paper deals with the design achievements on an active antenna able to guarantee the link with the chosen geostationary satellite in Ku band in order to supply in flight entertainment services on aircraft. The aim is to realize a future affordable innovative commercial product based on an antenna system not containing any mechanical moving parts at the same time able to steer the beam as well as to align the polarization through the use of custom electronic device.

L. Russo

Papers

Sparse arrays for satellite communications: from optimal design to realization

Ka-Band active sparse arrays for SATCOM applications

A Hemi-Spherical Ku-Band Fully Electronic Antenna for Aircraft In-Flight Entertainment