Turnstile antenna for saddle pattern generation in Leo satellite applications

In this paper, design of a turnstile antenna in UHF band (465 MHz) is carried out. In this design the initial values for monopole lengths and their distances have been considered lambda / 4 and for antenna mounting angles to be 90 degree respect to ground plane (satellite body). The effects of monopole lengths, distances and mounting angle variations studied by antenna modeling with finite elements method (by HFSSV10). The results show that increasing monopole lengths, achieving sharper saddle shaped pattern and decreasing antenna mounting angles, making smoother radiation pattern. For monopoles distances, variation about 10% around lambda / 4 does not affect the radiation pattern, obviously. In this article, optimum values for aforementioned main parameters obtained by search method. The designed antenna with optimum values parameters fabricated and tested. The results represent a good agreement between simulation and measurement.