A K‐Band Dual‐Polarised Hetero‐Integrated Quasi‐Planar Transverse Electromagnetic Antenna

In this article, a design of the dual linear-polarised/dual circular-polarised transverse electromagnetic (TEM) antenna is presented, which is designed to operate in K-band (18–19.5 GHz). The Quasi-TEM wave is achieved by the low-profile metallic stepped horn antennas and the planar multilayer feeding structure. The cross-shaped slot and the multilayer substrate integrated waveguide (SIW) feedlines are adopted to achieve independent dual linear-polarised and dual right-handed/left-handed circular-polarised operations, as well as to minimise the antenna dimensions to around 0.7 wavelengths (𝜆0) × 0.7 𝜆0 and the antenna height to around 0.4 λ. Both simulated and experimental results are presented for the demonstration. Results indicate that both the linear-polarised operational mode and the circular-polarised operational mode of the TEM antenna provide wideband return loss (less than −10 dB) and 8.2–10.9 dBi(dBic) gain for the 18–19.5 GHz operating range, and the axial ratio (AR) is less than 3 dB simultaneously when the TEM antenna operates as a circular-polarised antenna.