A Miniaturized Patch Antenna With Independent Tuning and Decoupling of Two Copolarized Feeds

Common/differential mode cancelation method is applied to split a rectangular patch antenna into two half-sized copolarized patch antennas with isolated ports. The proposed decoupling structure consists of a meandered air gap between two halves of the patch with a common ground plane and two fences of short-circuiting pins arranged in parallel with the H-plane. With the optimal gap width and the shift between the fences, the capacitive and inductive coupling mechanisms between two halves cancel out. The decoupling structure is conveniently embedded into the same stack of two air-spaced dielectric substrates as both half-patches, as well as their fences of capacitive loads near radiating edges, added for miniaturization. Advantageously, the method allows for independent tuning and decoupling, avoiding slot defects in the ground plane, which simplifies the design procedure compared to other patch antenna decoupling methods. Moreover, the method guarantees decoupling within the entire resonant frequency band, in which both ports are matched. An antenna example constrained with total dimensions of 70 mm × 70 mm × 10 mm is designed for 800 MHz and is evaluated numerically and experimentally showing the same bandwidth as a classical patch of the same size.