Ultra-compact end-loaded planar dipole antenna for ultra-wideband radar and communication applications

A planar dipole antenna is loaded with LC-tank resonators and chip resistors presented for ultra-wideband (UWB) radar and communication systems. Each staircase rectangular arm of the proposed planar dipole is loaded with an open complementary double concentric split-hexagonal-ring resonator (LC-tank) and a pair of chip resistors at the end for bandwidth enhancement, whereas a broadband microstrip to parallel-plate transformer (or balun) is applied as the feeding structure of the antenna to provide impedance matching as well as balanced-unbalanced transition. The measurement results show that the proposed antenna operates over a frequency bandwidth of 0.64-3.8 GHz with <;i>S<;/i><;sub>11<;/sub> <; -15 dB and exhibits highly directive radiation patterns for the first 100% of the operating bandwidth (0.64-2 GHz) with gains in the range 2.2-4.2 dBi.