Antenna aperture size reduction using subbeam concept in multiple spot beam cellular satellite systems

Abstract

[1] Multiple beam configurations in satellite systems enable the reuse of frequency in beams separated by a sufficient distance to address bandwidth limitation issues. Phased array antennas can simultaneously produce a large number of spot beams directed toward specific areas and therefore are a natural platform for multiple-beam satellite communications. This paper discusses a method to generate a large number of spot or cellular beams for multiple-beam satellite systems using smaller apertures. The basic spot beam is divided into a number of smaller subbeams with lower crossover levels that operate within the same bandwidth as the spot beam. The frequency reuse configuration can be maintained, while the overall aperture size is reduced. The aperture reduction is shown to have little or no effect on the cochannel interference. The technique is applicable to all satellite orbits as well as high-altitude platforms.Citation: Kilic, O., and A. I. Zaghloul (2009), Antenna aperture size reduction using subbeam concept in multiple spot beam cellular satellite systems, Radio Sci., 44, RS3001,

Reflectarray to Generate Four Adjacent Beams per Feed for Multispot Satellite Antennas

“…= D-sin{6bi(i)\ where D is the diameter of the reflectarray. The relation between the directions 6b 1 and #42 and the distances d\ and di can be obtained by subtracting the phase delays associated to each frequency, shown in (2) and (3). This relation is presented in (4) and can be used to compute the feed position from the values of d\ and di, so that the reflectarray is able to generate two beams in the directions 6bi and 0b2 at two frequencies/!…”

“…Different attempts have been made to generate a multiple spotbeam coverage with a single aperture [2], using direct radiating arrays (penalized by high complexity and cost) [3], [4], or a single oversized shaped reflector of 4.5-m diameter [5]. Recent works have proposed the use of reflectarray antennas [6] to reduce the number of apertures by generating two different colors per feed, either in two polarizations [7] or in two frequencies [8].…”

Application of Artificial Immune System Algorithm to Electromagnetics Problems

“…The strength of radiation from the center beam on to these co-channel beams can be seen from the antenna radiation pattern shown in the background. The overall interference can be reduced by synthesizing the array antenna so that radiation into these co-channel beams is reduced, [19]. Our objective in this example is to reduce the side lobe levels (≤ −30 dB) within the co-channel beams in the first tier by an amplitude control.…”

Interference in Cellular Satellite Systems

“…Recently a new method has been presented for reducing the cost of satellite antennas by sizing the antennas for lower power levels than the conventional approach, while maintaining the edge gain requirements, (Kilic and Zaghloul, 2009). This approach relies on the partitioning of the spot beam into a number of sub-beams.…”

“…Section 3 discusses a new method of defining beam coverage on earth, referred to as sub-beam coverage. The motivation is to keep the coverage on earth identical but reduce the satellite antenna size as much as 50% (Kilic & Zaghloul, 2009). The advantages and overall performance of the sub-beam approach in terms of interference is the subject of Section 3.…”