EHF Rotman Lens Fed Linear Array Multibeam Planar Near-Field Range Measurements
Authors: Mike Maybell, John Demas
Realized gain measurements of a 44 beam 44 element linear array over a 43.5 to 45.5 GHz design frequency range are presented. The prototype array1 is designed as a single column of a 50 column multibeam 2200 element planar active receive array for geostationary satellite communications payload. The 2200 element planar array is designed to form 1760 simultaneous narrow 0.4 degree beams, 1463 of which intercept the earth. The multibeam single prototype column realized gain was tested at the Nearfield Systems Inc.'s (NSI) facility using a 12’ x 12’ Planar Near-Field Range. Two different linear array configurations were tested. Each configuration utilized the same WR-19 waveguide fed 44 beam, 44 element Rotman lens and integrated RF distribution network (RFD). An active receive array utilizing only the center 8 array elements of the Rotman lens feed was tested first. This was followed by a 44 array element passive array test demonstrating the narrow 0.4 degree half power beamwidth. Summary and specific examples of the NFR test results will be presented. These will be compared with that predicted using the previously measured lens array factor gain (AFG) and embedded element realized gain. The AFG was measured using a HP8510C automatic network analyzer.