Broadband suspended plate antenna with probe-fed strip

The paper demonstrates a new means of achieving a broad impedance bandwidth with a simple mechanical structure and low cross-polarisation levels for a suspended plate antenna with a co-axial probe-fed strip. The feeding-strip co-planar with the plate has a capacitive coupling with the plate. which e ffectively wipes out large inductance due to the long probe and gives rise to a broad impedance bandwidth. The narrow feeding structure avoids unwante d change of the current distribution at the plate surface and therefore. im proves the polarisation performance to some degree. Furthermore, the co-pla nar feeding configuration simplifies the mechanical structure of the antenn a. As examples. two rectangular suspended probe-fed strip single-layer plat e antennas were made and examined experimentally. Measurements demonstrate good performances with broad impedance bandwidths up to 36%, stable radiati on patterns with cross-polarisation levels of less than -17dB, and gains of 4-5dBi.