A Multiport Microstrip Grid Array Structure

This communication presents a multiport microstrip grid array structure, which gives the flexibility to use it as a single antenna or multiple antennas. To realize such a structure, the key challenges are impedance matching and port isolation. It is shown that impedance matching can be made with stepped-impedance lines and port isolation can be enhanced from the defected ground plane. A particular example of 145 radiating elements with four ports is implemented in RT/duroid 5880 substrate for 24-GHz applications. Simulated and measured results are compared, which verifies the design, analysis, and versatility of the structure.