Microstrip line matched normal mode helical antenna for cellular communication

A normal mode helical antenna was designed to operate at 900 MHz. The input impedance of the helix was matched through a microstrip line of a quarter wavelength long. The antenna was simulated with an infinite ground plane. An axial wire between the helix and the microstrip line was introduced in order to reduce the coupling and an end wire to vary the input impedance to a value desired for a narrow microstrip line. The overall performance is presented.