Theoretical anisotropic transverse resonance technique for the design of low‐profile wideband antennas

The authors derive an anisotropic transverse resonance technique enabling the design of a low profile, wideband radiating rectangular cavity. They calculate a tapered geometry that preserves an effective half wavelength resonance within a cavity partially loaded with an anisotropic medium. This design results in an antenna profile of λ o /24, with 1.4 octaves of bandwidth, and a realised gain of 3.3–7.2 dB from 210 to 505 MHz. Using an adaption of a coaxial line to waveguide transition, which utilises two flat rectangular probes as a two‐port matching network, as well as an external 180° hybrid coupler as a phase splitter, they achieve a voltage standing wave ratio of better than 2:1 across the whole band.