Dual-Band Transmission Surfaces With Small Frequency Ratio and Sharp Skirt Frequency Response

Abstract

Two dual-band transmission surfaces with/without polarization conversion are proposed. They have a small frequency ratio and sharp skirt frequency response. Both configurations consist of a receiving antenna, a back-loaded radio frequency circuit (BLRFC), and a transmitting antenna. The receiving/transmitting antenna is a tightly coupled dipole antenna (TCDA) array and the BLRFC is a dual-band band-pass filter with a small frequency ratio. Two transmission bands are achieved, one is 5.15 to 5.4 GHz, the other is 5.75 to 5.95 GHz. The center frequency of each operation band is 5.28 GHz and 5.85 GHz, respectively, and the frequency ratio between the upper and lower bands is 1.1. Both bands have a sharp skirt frequency response. The dual-band transmission surfaces with/without polarization conversion characteristics can be used as shielding walls in Intensive Care Units (ICU) to shield signals except those in the pass-band.