Solderless circularly polarized microwave antenna element

Abstract

Disclosed herein is an antenna feed design for transmitting or receiving a circularly polarized microwave signal, and a communication device using that antenna feed design. Resonating disks are bowl-shaped to balance E-plane and H-plane magnetic field patterns, decreasing cross-polarization, and providing mechanical rigidity. A non-planar circuit replaces planar microstrip transmission lines for transmitting the signal, with 90° phase shifts, from an input point to excitation points. This non-planar circuit overcomes some of the layout problems encountered in planar circuits. It maintains impedance matching from the input point to the excitation points by progressively tapering down the characteristic transmission line impedance of each successive section. The non-planar circuit has sufficient mechanical strength and rigidity to allow it to be supported at only two anchor points. Similarly, the non-planar disks are also of sufficient strength to require only a single anchor point each. Thus, the antenna parts do not require any additional dielectric substrate support, and all parts are DC grounded. The use of fingers surrounding the ground plane and extending towards the resonating disks results in improved off-boresight polarization. All components of the antenna feed are built and combined without the use of solder or dielectric substrate support, creating a stable, corrosion-resistant, low-cross polarization antenna.