Array Antenna With Increased Element Separation Based on a Fabry-Perot Resonant Cavity With AMC Walls

A new method is presented for increasing the separation between the radiating elements of a I-D array antenna by incorporating it into a Fabry-Perot type resonant cavity with artificial magnetic conductor (AMC) walls. The AMC walls create a more uniform distribution of field within the cavity and, moreover, eliminate diffracted fields. The concept is demonstrated via 3-D full-wave simulations as well as experimental measurements for a prototype antenna. Comparison between an antenna with AMC walls and an identical reference antenna, without walls, shows a reduction in the sidelobe level. An array element separation of 2 A is achieved whilst maintaining good radiation performance. The performance of the proposed structure is also compared to that of an antenna incorporating PEC walls. Finally, the effect of the side-wall and central AMC walls are considered separately in order to isolate their corresponding effect on the antenna performance.