Asymmetric Half-Bowtie Antennas With Tilted Beam Patterns

A novel geometrical change is introduced to a broadband bowtie antenna to allow radiation beam tilting without the use of an engineered material. By halving the bowtie arms along their horizontal axis of symmetry and judicially removing parts of it, the phase line of the antenna can be controlled to achieve various magnitudes of tilted radiation patterns. Further bandwidth improvements are realized when the traditional triangular antenna is replaced with an elliptical equivalent. Using either geometry, the amount of tilt in free space across its bandwidth could vary from 0° to 60°. For the printed case, a unidirectional antenna pattern is tilted to approximately 40° along the useable bandwidth of 32% with a peak gain of about 5 dBi and a front-to-back ratio greater than 10 dB. A prototype antenna is fabricated and tested. The measured results satisfactorily validate the numerical ones.