Quadruple-fed Aperture-coupled Microstrip Patch Antenna for On-antenna Power Combining

A novel technic of on-antenna power combining based on a quadruple-fed off-centered aperture-coupled microstrip patch antenna (ACMPA) is proposed in this paper. Four driving signals are combined into two off-centered apertures electrically coupled to a radiating patch antenna. As a result, higher efficiency and improved transmitted power are achieved by removing lossy power-combiner either implemented on printed circuit board (PCB) or on monolithic microwave integrated circuit (MMIC). Moreover, compared to a dual-polarized centered aperture-coupled microstrip patch antenna, this type of feeding reduces the cross-polarization level as each slot is separated. As a proof of concept, the passive and active versions of the antenna are designed and fabricated at 2.45 GHz. For comparison purpose, the single-ended off-centered aperture-coupled passive and active versions are also fabricated. The results show +5.6 dB of transmitting power compared to the single-ended active version, demonstrating the on-antenna power combining capacity of this type of antenna while keeping a symmetrical radiation pattern and very good cross-polarization levels.