Printed Cactus Monopole Antenna with Enhanced Impedance Bandwidth

Previously proposed "cactus" designs of wideband printed monopoles reported impedance bandwidths of 1:4. Here, the "cactus" topology is re-designed to enhance the impedance bandwidth to 1:8 with moderately increased electrical size. The proposed antenna is printed on an 18 cm by 15 cm FR-4 substrate. It is designed for an impedance bandwidth from 700 MHz to 5.6 GHz with a return loss better than 10 dB. Simulation and measurement results are presented and compared. Strategies for improving the accuracy of the simulation are discussed. The application is a monostatic surveillance radar utilizing two pairs of identical antennas oriented for co- and cross-polarization.