tailieunhanh - Satellite Communicationsever increasing widespread Part 16

Tham khảo tài liệu 'satellite communicationsever increasing widespread part 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 516 Satellite Communications Fig. 2. Ku-band Active Phased Array Fig. 3. 4x8 Shelf in Ku-band BFM This design approach for the BFM provides several advantages including modularity reproducible assembly and performance. Broadband Wilkinson dividers and combiners provide inherently good amplitude and phase balance between the paths. Furthermore path-to-path insertion loss variations can be minimized by the appropriate selection of MMIC phase shifter modules so that low loss phase shifters are matched with high loss paths and vice versa. The power amplifier design combines MMIC and quasi-monolithic technology to achieve optimum DC-to-RF conversion and linearity while simultaneously meeting output power System Aspects of Active Phased Arrays 517 and size requirements. The amplifiers are designed to be integrated directly in back of the array to minimize total output losses. X-Band High-Power Active Phased Array A study performed at COMSAT Laboratories addressed a set of requirements for a future DSCS system Zaghloul 1996 . A key antenna specification is to transmit four beams simultaneously. These beams are to be shaped and steered independently and can range in size from the minimum of 2 to the full earth coverage of 17 . An EIRP of 50 dBW is required for the 2 beams and the overall antenna mass and DC power consumption are to be minimized with goals of 200 lb. and 400 Watts respectively. Fig. 4. Demonstration X-band array for DSCS system A proof-of-concept array was developed as a subarray of such an antenna and aims at demonstrating the most critical components required of a full-up active array antenna. This demonstration array shown in Figure 4 utilized a total of eight radiating elements to form two independently steerable and reconfigurable beams. A key component developed for the program is the Beam Forming Matrix BFM whose function is to shape and steer the beams. The BFM implements modular MMIC technology in its phase shifters and attenuators which .