Square planar monopole antenna

A planar monopole may be realised by replacing the wire element of a conventional monopole with a planar element. In this case, the planar element which is square, is located above a groundplane and fed using an SMA connector as illustrated. The square monopole has a simple geometry and a smaller bandwidth compared to the circular-disc monopole. However, it is still a broadband antenna with a typical impedance bandwidth of 75 % at S band. This broadband antenna shows a constant radiation pattern over the impedance bandwidth. A simple formula for the frequency corresponding to the lower edge of the impedance bandwidth, which has an accuracy of /spl plusmn/8.5 % over the frequency range 1 GHz to 6 GHz, is proposed. The effect of the feedgap distance is also examined.