Sub-beam concept is very useful for size reduction of multiple beam phased array antenna (PAA) systems that are applied for high-throughput communication satellites. In this paper, the synthesis procedure for a PAA with multiple sub-beams in two dimensions of the coverage domain is proposed and analyzed. In the design procedure, the interleaved sub-arraying technique has been applied to eliminate the grating lobes. The extremely short angular distance between adjacent sub-beams is challenging. An innovative beam forming network is proposed, which can generate multiple orthogonal sub-beams while keeping the required angular distance between sub-beams. To demonstrate the effectiveness of the design technique, an example considering the requirements derived from conceptual design of a high-throughput communication payload is presented. The array is optimized using the genetic algorithm while taking into account the technical requirements of the antenna. The gain patterns exhibit a 0.4° angular distance between adjacent sub-beams. In addition, the number of sub-arrays and element spacing guarantee the orthogonality of the sub-beams. The calculated carrier to interference ratio in the synthesized array shows that it has acceptable values in each spot. The aperture size reduction in the synthesized array compared to a conventional multiple beam array is more than 36.7%.
Summary
In this paper, the number of spots and cluster size of a high‐throughput satellite (HTS) is optimized by minimizing the satellite mass in the conceptual design phase. An innovative procedure for deriving the total mass of the payload and relevant power supply subsystem as a function of the number of spots and cluster size is presented. For estimating the size and electrical power consumption, the general block diagram of an HTS payload is planned. A direct radiating phased array as the multiple‐beam antenna is used, and its synthesis technique is described briefly. Accordingly, the number of subarrays and elements in each subarray as functions of the number of spots are derived in the presence of orthogonal beams while neglecting the grating lobes. A block diagram for the new generation HTS payloads with digital signal processors for beam forming and data regeneration is presented. The procedure for determining the number of spots and cluster size is extended to the new generation very HTSs with 100 s Gbps link capacity. Conceptual design examples of HTSs with microwave beam forming network and transparent transponder in C‐band, Ka‐band, and for very HTSs with digital beam forming network and regenerative transponder in Ka‐band are provided.
This paper presents the application of a genetic algorithm (GA) to the optim ization of an S-band quad rifilar-helical antenna, which is printed on a dielectric cylinder. This antenna was designed for LEO satellite applications. Its saddle shaped pattern should compensate fo r free-space loss variations in the satellite's footprint. The steady-state genetic algorithm was used fo r this optimization and an elitist strategy was implemented. The selection strategy in the present genetic algorithm was proportionate selection.
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