Ultrawideband TEM Horn Circular Array

An eight-element circular array of miniaturized combined transverse electromagnetic horn and loop elements for joint frequency and time operation is presented. The use of such ultrawideband and compact directional element leads to stable wideband radiation patterns with moderate gain for omnidirectional phase mode 0 of operation. Moreover, a directional mode enabled by simply exciting specific element(s) in the array is also demonstrated. Obtained directional beams can be steered to a desired direction in horizontal plane simply by exciting an appropriate element. Low dispersion of the utilized element permits distortionless pulse radiation for both modes of operation. The performance of the proposed array is characterized computationally and experimentally in frequency and time domains for both modes. The fabricated circular array has VSWR <; 2, good omnidirectional (wobble on the wave <;5 dB) and directional (front to back ratio >10 dB) radiation characteristics, nominal gain >6 dBi, cross polarization level <;-15 dB, and excellent time-domain performance with high-fidelity factor over more than two octaves.