Oversized elements for high efficiency extremely high frequency boresight array

by Gray, Derek

High gain, planar array antennas which operate at rnillimetre wave f?equencies, and can be mass produced at low coq are desired by industty. The design of such arrays continues to be academicaii y challenging. A literature review was conduc ted covering patents and papen describing antenna arrays either operating at. or suitable for operation at, millimetre wave fiequencies. Four presently under exploitai technology types were identified. Two of the under exploited technologies were investigated. Both small and medium sized arrays of non-radiating edge fed microstrip patches were built up in a consistent process. The design of the patcli and Lx2 subarray were shown to affect the radiation pattern behaviour of 16x16 arrays. The placement of nulls in the 2x2 subarray radiation patterns proved critical to the rnitigation of grating lobes, which were a source of directivity loss. A considerable ciifference in directivity characteristics across 10% bandwidth was found between in phase and 180' feeding within the 2x2 subarrays. An optimised 1 80' fed 4x4 subarray presented an improvement over pnor work. Changing the boundary conditions at the juricture of the base and rim of the cavity of short bacldire antamas was found to alter the dircctivity. Large diameter short backfire antennas with choked, inclined and curved junctures prodiiced 11igh directivity. A readily machinable design was used in a smaii array, to demonstrate its utility as a high aperture efficiency array element . The redts are of importance to the future development of Iow cost, planar or quasi- planar antenna arrays, particularly at millimetre wave fiequencies.