5‶1 bandwidth, dual-polarized dielectric rod antenna

Abstract

Summary form only given. Dielectric rod antennas (DRAs) are commonly used as reflector feeds and nearfield probes because they exhibit single broadside beam, good polarization purity, wide bandwidth and low scattering cross section. Particularly for multiple reflector feeds, low cross-coupling and polarization purity of DRAs make them very attractive. More importantly, DRAs provide ultra-wideband (UWB) operation with a simple and easy-to-fabricate, cost-effective structure. However, the maximum achievable bandwidth is typically limited by the waveguide feed at the low end and the onset of higher-order modes of the dielectric rod at the high end of the frequency range. In the past, multi-layered DRA designs (C.-W. Liu and C.-C. Chen, “A UWB Three-Layer Dielectric Rod Antenna with Constant Gain, Pattern and Phase Center,” IEEE Transaction on Antennas and Propagation 60(10), Oct. 2012) have been utilized to increase the frequency coverage. However, this adds significantly to design and manufacturing complexity. In this paper, we present a novel, UWB DRA machined entirely from bulk rexolite_1422 material that covers the 6-32GHz range. A dual-polarization, tapered twin-lead structure was integrated on the feed taper of the dielectric rod to provide a transverse electromagnetic (TEM) structure and avoid the waveguide cutoff at the low end of the frequency band. A surface-mount RF switch is integrated into the feed for polarization control. The dielectric rod is made up of a uniform dielectric material, as such, its fabrication is low-cost and straightforward using standard milling tools. The design was optimized to cover the 6-32GHz band with a stable phase center, a symmetric pattern and a high realized gain (>10dB). A prototype was fabricated and tested up to 20GHz. The measured realized gain was >10dB and the measured radiation patterns exhibit low side lobes (SLL<;-20dB) and agree well with the design in both the Eand H-planes. The return loss was below -10dB over a record 5:1 frequency band, spanning 420GHz.