Printed planar monopole antenna with electromagnetically coupled elements

Planar monopole antennas and dual plate antennas have been reported to yield wide bandwidths. Printed monopole antennas have previously been shown to be implementable on planar dielectric substrates using low cost microstrip printing techniques. In this paper, the addition of an electromagnetically- coupled element to the printed planar monopole antenna is investigated. While remaining simple to construct, modifications to the electromagnetically-coupled element are shown to reduce the lower edge frequency of the 10dB impedance bandwidth by up to ∼ 19% (280 MHz at 1.5 GHz). The radiation patterns for these antennas are characteristic of monopole antennas - i.e. omnidirectional in the azimuth plane with a null at the zenith - and are consistent within +/- 2dB across their useful impedance bandwidths. By optimizing the feed arrangements on these antennas a 10dB impedance bandwidth ratio of over 3:1 can be achieved. This technique yields the ability to construct a smaller antenna, in comparison to a simple printed planar monopole antenna, for a given frequency range. The antennas considered in this paper operate between 1.3 and 5.5 GHz, making them suitable for numerous mobile and portable applications. Measured results are compared to antenna simulations using Transmission Line Modelling.