Reflector synthesis for wide-scanning focal plane arrays

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Abstract

A new complex offset double-reflector configuration for a wideband focal plane array (FPA) is presented which is optimized for Ka-band applications with a scan range of ±20° in the azimuth plane. This configuration is obtained by using a mathematical framework based on geometrical optics which allow us to optimize complex double-reflector FPAs with limited computational effort. The proposed reflector configuration maximizes the number of simultaneously active array elements of the phased-array feed and minimizes the required total number of array elements for this wide scan range. To realize an aperture efficiency of at least 80% at 30 GHz, our concept allows half of the antenna elements in the array to be active during scanning for a scan range of ±10° and at least a quarter of the array elements to be active for a scan range of ±20°. This is a major improvement as compared to the scanning capabilities of focal-plane arrays based on conventional single- and double-parabolic reflector configurations. In addition, the FPA configuration has been optimized for wideband optical true-time-delay beamforming which requires a linear phase distribution along the array elements. We obtained a phase linearity with rms error of 2.81° at 30 GHz. The experiments from the realized prototype demonstrate a good agreement between simulation and measurements and fully prove the required scanning performance over a ±20° scan range. The prototype demonstrates a high directivity up to 46 dBi at 30 GHz and 48 dBi at 40 GHz and reflector efficiency up to 83% at 30 GHz and 77% at 40 GHz.

Original languageEnglish
Article number8621011
Pages (from-to)2305-2319
Number of pages15
JournalIEEE Transactions on Antennas and Propagation
Volume67
Issue number4
DOIs
Publication statusPublished - 1 Apr 2019

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Keywords

  • Antenna array
  • effective isotropic radiated power (EIRP)
  • focal-plane arrays (FPAs)
  • geometrical optics (GO) modeling
  • millimeter-waves (mm-waves)
  • reflector antennas
  • wide scan range

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