A Novel Compact Superwideband Bowtie Antenna for 420 MHz to 5.5 GHz Operation

Bowtie antennas are ubiquitous in practical ground-penetrating radars. In spite of having a wide impedance bandwidth, boresight gain of these antennas is small and the main beam gets tilted beyond a 4:1 bandwidth. In this paper, a bowtie antenna design is presented, which has a return loss of at least 10 dB from 420 MHz to 5.5 GHz (13:1 bandwidth) and a stable radiation pattern and improved gain throughout the bandwidth. A superwide bandwidth is obtained without any kind of dissipative loading. The peak gain and average gain are 7.96 and 5.89 dBi, respectively. The gain of the antenna is improved using parasitic loops as directors. The size of the antenna is only 0.322λ at 420 MHz.