Design of A Miniaturized Dual-Polarized P-Band Antenna for Near-Field Measurements

In this paper, a miniaturized dual-polarized P-band antenna operating from 0.2 GHz to 5 GHz is proposed. Near-field measurements at low frequency bands often suffers from low gain, large profile, and limited polarization isolation of the applied antenna elements. In response to these problems, a specially design resonant structure with resistive loading is added to the travelling wave antenna in order to realize the miniaturization of the antenna. By further combining with exponential slots at the edge of the radiation flares and an optimized trapezoidal feed structure, both ultra-wideband characteristics and improved directivity at the lower frequency band are achieved. The final design is miniaturized to 0.2?*0.23?, where ? is the free-space wavelength at the lowest frequency. The antenna is fabricated and measured, the return loss of the antenna is less than -10 dB from 0.2 GHz to 5 GHz achieving 184.6% fractional bandwidth, the polarization isolation is less than -20 dB, and the gain level is higher than 4 dBi over the entire operational bandwidth.