Wideband Parallel-Plate Waveguide, Phased-Array Antenna
NAVAL RESEARCH LAB WASHINGTON DC
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A need exists for wideband phased array radars. This report presents the results of some experimental studies made on improving bandwidth and scanning range performance of phased array antennas. A parallel plate waveguide element, operating in the S band 2.8 to 4.2 GHz was used as the radiating element. SUch an element permitted the needed less than one-half wavelength interelement spacing for broadband applications and has been found to provide good aperture matching for H plane scanning. The element is fed by a broadband, end on, base fed, coaxial to waveguide transition. H plane waveguide simulators have been used to study aperture match performance and to optimize array parameters to improve bandwidth and scan range. The waveguide simulator results showed that a good aperture match, with voltage standing wave ratio VSWR of about 2.1 over a 40 bandwidth and or - 60 deg scan angle, is achievable for H-plane scanning. Experimentally optimized array parameters are then used to build an 11 x 11 element array. The scanning performance of that array in H and E planes was studied by measuring active element patterns. This does not give precise results, but did show that the aperture match is about equally good, over or - 60 and 40 bandwidth, for H and E plane scanning. Keywords Phased arrays Wide bandwidth Experimental studies Aperture matching Parallel plate waveguides Waveguides simulators Active element pattern.
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