A Q/V Dual-Band Dual-Circularly Polarized Shared-Aperture Phased Array Antenna with Limited Field of View Scanning

This paper presents an 8x8-elemnet dual-circularly polarized (CP) shared-aperture phased array antenna (PAA) with large element spacing (LES), designed for limited field of view applications in Q- and V-bands. The elements operating in both bands follow a unified design method. Left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) are achieved through a 90 degrees hybrid coupler integrated into the multi-layer printed circuit board (PCB). The radiation pattern is shaped by an umbrella-shaped lens attached to the PCB using a metal block, creating a flat-top active element pattern (AEP) to suppress grating lobes during beam scanning. The 4x8-elemnet Q-band array (37.5-41.5 GHz) and the 4x8-elemnet V-band array (47.0-51.5 GHz) are arranged in a staggered configuration within the 8x8-element shared-aperture Q-/V-band array. A prototype of the 8x8-elemnet PAA is designed and measured for AEP. The Q-band array achieves a 24.6-dBic boresight gain with a +/- 18 degrees scanning range, a 0.6-dB gain variation, and a -8-dB grating lobe level. The V-band array achieves a boresight gain of 25.4 dBic with a scan range of +/- 20 degrees, a gain variation of 1.2 dB, and grating lobes less than -10 dB.