The effect of fabrication tolerances on a suspended plate antenna

A suspended plate antenna (SPA) with L-probe feed is of interest as an efficient non-contacting feed method. It maintains high efficiency even when the plate is constructed of poorly conducting materials such as conductive inks. An SPA is designed at 10 GHz where fabrication tolerances can have an impact on performance. The SPA as designed has 36 percent impedance bandwidth and 8 to 9 dBi of gain. The prototype has a somewhat different impedance bandwidth indicating that the as-built plate is slightly tilted and different in size owing to fabrication errors. A tolerance analysis is shown to confirm the sensitivity of this design to fabrication accuracy at high frequency. The CEM model is adjusted to better represent the prototype antenna for a simple metal plate on foam support and also for a microstrip version on a thin substrate.