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nasa scientific and technical aerospace reports phần 2

Nguồn cảm ứng cùng ăng-ten như anten microstrip trong triển lãm chung chỉ có một băng thông nhỏ. Các nỗ lực khác nhau đã được thực hiện để tăng băng thông của anten microstrip, bao gồm cả việc sử dụng các chất nền dày hơn, các yếu tố ký sinh trùng và trở kháng phù hợp với mạng lưới. | 20050169653 Paderborn Univ. Germany Broadband Dual Polarised Microstrip Antennas with Improved Beam Forming and Gain Capabilities Schwenzfeier Eva IEEE Antennas and Propagation Society International Symposium Volume 1 1999 pp. 120-123 In English See also 20050169565 Copyright Avail Other Sources Proximity-coupled antennas like microstrip antennas in general exhibit only a small bandwidth. Different attempts have been made to increase the bandwidth of microstrip antennas including the use of thicker substrates of parasitic elements and of impedance-matching networks. Although the bandwidth may be increased for the reception of one polarisation the results achieved in prior art are not sufficient for DTH Direct-To-Home satellite reception. A dual polarised antenna is required from 10.70GHz to 12.75 GHz relative bandwidth 17.5 . Extensive research in our department led to a special kind of broadband proximity-coupled and dual polarised antenna. This two-layers configuration is characterized by a simple structure. Based on this antenna two novel microstrip antennas were developed which additionally guarantee beam forming and increase gain. These improved antennas are suitable in antenna arrays to reduce the number of elements and to simplify the feeding network. Another more often used DTH reception unit is a combination of a parabolic reflector a feedhorn and a LNB Low Noise Block Converter . As illustrated in it is preferable to avoid the transition loss from hollow waveguide i.e. the feedhorn to planar waveguide technology i.e. the LNB by replacing the feedhorn with a single microstrip antenna. An improvement of beam forming hence is very important for the illumination of the reflector. Therefore the two novel antenna elements are the main issue of this contribution. Author Broadband Polarized Electromagnetic Radiation Microstrip Antennas Beamforming 20050169659 Chan Technologies Inc. Kirkland Quebec Canada A Circularly Polarized Waveguide Array for LEO Satellite .