Broadband Printed Dipole Antennas

Abstract

Two arms of Microstrip Dipole antenna are printed on the same side of a substrate. But two arms of the Printed Dipole Antenna (PDA) are printed on the opposite sides and hence contain no ground plane. The Return Loss (RL) Bandwidth (BW) of PDA is much higher compared to Microstrip Dipole as it does not contain ground plane like the Microstrip Dipole and therefore Q value is low which results in large RL bandwidth. The PDA is fed by printed version of two wire transmission line. The cross polar discrimination is high as width to length ratio of the arm is very small. In general the width is kept below 0.05λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> . A novel design of PDA is reported in which the antenna arms have been widened to make it a Flag shaped to achieve large RL bandwidth. The -10dB RL bandwidth as high as 76% is achieved. Due to widening of the arms the fundamental resonant frequency and its first harmonic is stagger tuned to result a high RL. Three antennas are designed and simulated in MOM based simulator IE3D. One of them has been fabricated for experimental verification. The experimental result is in good agreement with the simulated results.