Low profile cavity-embedded ultra-wideband UHF array antenna with end-fire beams

A low profile, vertically polarized, ultra-wideband array antenna with end-fire beams operating in an ultra-high frequency (UHF) band is developed in this paper. The array antenna consists of 1×16 log-periodic top-hat loaded monopole antenna arrays and is feasible to embed into a shallow cavity to further reduce the array height. Capacitance is introduced in the proposed antenna element to reduce profile height and the rectangular top hats are carefully designed to minimize the transverse dimension. Simulated results show that when the antenna array operates in a frequency range of 300 MHz–900 ​MHz, the end-fire radiation pattern achieves ±45° scanning range in the horizontal plane. Then prototypes of the proposed end-fire antenna element and a uniformly spaced linear array (1×2) are fabricated and validated. The end-fire antenna array should be suitable for airborne applications where low profile and conformal scanning phased antenna arrays with end-fire radiations are required. This design is attractive for airborne platform applications that are used to search, discover, identify, and scout the aerial target with vertically polarized beams.