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

Abstract

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 λo/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.

An overview of ARL's low profile antenna work utilizing anisotropic metaferrites

“…We note that this technique was not utilized by Metamaterials Inc. in the design of the A133 or the A145 LPAs. Furthermore, we present the most interesting results here, but more detailed derivations and designs are given by Mitchell and Wasylkiwskyj in references [4] and [5].…”

“…Equation (5) shows that for the particular orientation of Fig. 8 the transverse resonance of the cavity is determined solely by the frequency of resonance, z, and y.…”

“…We see that the VSWR stays below 2:1 over this bandwidth as well. The stability of the VSWR curve can be attributed to the constancy of the transverse resonance within the cavity which is established by equation (5).…”

“…Transmission line representation of a partially loaded rectangular cavity bounded by two perfectly conducting walls at x = +/a(z)/2[5].…”

Tunable phase shifter in substrate integrated waveguide

“…where k x is the wavevector in the waveguide. In TE mode, the equivalent voltage (V) and current (I) are set equal to the vertical electric (E y ) and longitudinal magnetic (H z ) fields respectively [29]. If the electric field is independent vertically, then the impedance voltage will be E y b, where b is the height of the waveguide.…”