An Ultrawideband H-Plane Monopulse Log-Periodic Antenna for Jamming Signal Finding

This communication proposes an ultrawideband (UWB) H-plane monopulse log-periodic antenna designed for UAV applications in jamming signal detection. The main radiators are two log-periodic dipole antennas (LPDAs). Good isolation between the two LPDA elements is achieved through the common mode (CM) and differential mode (DM) cancellation methods. The spacing factor of the LPDAs, and the distance between the elements are adjusted to improve DM matching and CM matching, with the radiation patterns also considered to ensure the detection distance, correctness, and accuracy of the direction-finding system. The balanced feeding network consists of a UWB monopulse comparator, parallel lines, and tapered microstrip lines. The proposed antenna operates in a band exceeding four octaves (1.45–5.95 GHz) for both the sum and differential ports, covering the GPS band (1.575 GHz) and Wi-Fi bands (2.4, 5 GHz). It exhibits low-ripple radiation patterns, a sum beam gain above 10.5 dBi, a null depth below –20 dB, and a front-to-back ratio exceeding 14 dB.