A Novel Compact Double Exponentially Tapered Slot Antenna (DETSA) for GPR Applications

A novel compact double exponentially tapered slot antenna (DETSA) for GPR applications is presented. To extend the antenna's impedance bandwidth, the antenna arms are rolled back and lengthened, and lumped resistors are used near the ends of the rolled arms. An improved coplanar waveguide (CPW) to coupled stripline (CPS) transition for feeding is also investigated. The measured transmission loss of two back-to-back CPW-to-CPS transitions is less than 2.6 dB in the frequency band of 200 MHz-6 GHz, which agrees well with the simulated result. The measured S-11 of the antenna in frequency domain is less than - 10 dB in the band of 220 MHz-6 GHz, and it is also verified that the resistors mainly have influence on the antenna's S-11 below 1 GHz. The measured reflected pulses show that there are only two reflecting points, and the reflection is weak. The simulated and measured antenna gains at boresight show little variations with loading resistors of different values, and this means that the resistive loadings do not affect the gain characteristics of the antenna. The antenna's transmission response in time domain is also tested, and its application in GPR detection of a buried target is validated by experiments.