Design of the dual-shaped triple layer pillbox antenna

[摘要] ENGLISH ABSTRACT: The triple layer pillbox antenna is an antenna topology well suited for use as a stackable plank element in radar applications. Its suitability arises from the folding which makes it compact,and from the layered nature which can be exploited for low cost manufacture. Existing designs of these cheese antennas, whether two or three layers, suff er from two drawbacks: a) The bend or fold between layers introduces undesirable reflections and b) Due to their parabolic sector geometry virtually no pattern control is available to the designer. This work addresses both of these shortcomings.A low reflection transition is realized by introducing simple compensating elements into thedesign which, with minimal manufacturing complexity, off er high performance over a broadfrequency and incidence angle range. To cater for pattern control the concept of dual shapedreflectors is borrowed from the high performance dish antenna literature and implemented inthe pillbox geometry. This shaping off ers limited but useful control of the aperture distributionand thus indirectly over the radiation pattern.To test these innovations three X-band antennas have been designed, built and measured. Aninitial unshaped geometry is used for the fi rst design to show the fold or bend performance. Thisantenna has a simulated and measured 2GHz usable bandwidth, with a reflection coeffi cientbelow -10dB and side-lobes below -27dB over a bandwidth in excess of 20%. Shaping is thenadded to show how either side-lobe levels can be lowered to below -32dB, or the gain enhancedby 2dB. The enhanced designs have been built and experimentally veri fied.

[发布机构] Stellenbosch University