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 effectively wipes out large inductance due to the long probe and gives rise to a broad impedance bandwidth. The narrow feeding structure avoids unwanted change of the current distribution at the plate surface and therefore, improves the polarisation performance to some degree. Furthermore, the co-planar feeding configuration simplifies the mechanical structure of the antenna. As examples, two rectangular suspended probe-fed strip single-layer plate antennas were made and examined experimentally. Measurements demonstrate good performances with broad impedance bandwidths up to 36%, stable radiation patterns with cross-polarisation levels of less than –17 dB, and gains of 4–5 dBi.