Theoretical and Experimental Analysis of a Rolled-Dipole Antenna for Low-Resolution GPR

In this paper a rolled dipole antenna for low-resolution impulse ground penetrating radar (GPR) is theoretically and experimentally investigated. The antenna has been designed for transmission of monocycle pulses with duration of 5 ns (200 MHz central frequency) suitable for low-resolution GPR applications. The dipole is rolled to considerably reduce its length and resistive loading with the Wu-King profile is applied for suppression of late-time ringing, important for GPR. It is shown theoretically that the antenna radiates the pulse with no late-time ringing. Furthermore, by rolling the wires the antenna length is reduced by a factor of 4 with no evident negative impact on the antenna´s characteristics. A shield for the antenna has been designed, constructed and integrated with the antenna. Furthermore, it has been found that a tapered bow tie can be combined with the antenna in such a way that a significant increase in the antenna efficiency is obtained, resulting in a unique hybrid of a dipole and a bow-tie antenna.