Planar artificial magnetic conductors and patch antennas

Surfaces act as perfect magnetic conductors (PMC) if the phase shift of the reflection of an electromagnetic wave amounts to 180degrees compared to the reflection at a perfect electric conductor (PEC). One possibility to create PMC surfaces artificially is an array of closely spaced patches. In this paper, based on the relation between PMC surfaces and patch antennas, an explanation for the functioning of this artificial PMC is given. An equivalent network is derived that allows to understand the functioning and to provide a starting design for a numerical optimization by aid of fullwave methods. A planar PMC is used for the first time as a reflector for a large aperture coupled patch antenna array, especially in order to reduce the parallel-plate modes that are usually present in traditional aperture coupled patch arrays. An additional sidelobe suppression of over 6 dB has been achieved by the planar PMC reflector in comparison to a traditional reflector.