Design of Very Low Profile V/UHF Directional Metamaterial Antenna for Airborne FOPEN Radar

This paper presents a very low profile cavity backed planar V/UHF antenna, which has been introduced for possible intelligence, surveillance and reconnaissance (ISR) applications, namely for airborne foliage penetration radar. Multiple line slots on each half of the bow-tie and metamaterials inside the cavity are proposed for the wideband operation in the V/UHF band. The antenna operates in the frequency range of 240 MHz – 420 MHz with VSWR < 2.0:1 while maintaining positive realized gain with a maximum value of 4.5 dBi. The overall size of the proposed antenna is 0.36λ
low
x 0.36λ
low
x 0.04λ
low
, only 5 cm in depth instead of a quarter wavelength, corresponding to 85% size reduction.