Wideband Dual-Frequency Antenna With Large Frequency Ratio

This communication investigates a new type of compact dual-frequency antenna, which is realized by using a single rectangular dielectric block with a groove along its center. It integrates a microwave dielectric resonator antenna (DRA) with a millimeter-wave Fabry-Perot resonator antenna (FPRA). The DRA is fabricated out of a dielectric block, excited by a vertical conducting strip on its side wall. The FPRA is realized by sticking the adhesive copper tape on the surfaces of the groove, forming a pair of parallel plates and the ground plane. The FPRA is excited by a sleeve-integrated L-probe, which suppresses the cross-polar fields and widens the bandwidth of the FPRA. To validate the idea, a dual-frequency antenna, covering both the 2.4 and 24 GHz ISM bands, was designed and measured. The DRA operates in its TEx 111 mode, whereas the FPRA operates in its fundamental mode. Next, a wideband dual-frequency antenna was designed to further cover the 4G and future 5G frequency bands. Both of the TEx 111 and TEx 113 modes of the DRA are excited, broadening the bandwidth in the microwave band. Also, the FPRA mode and two L-probe modes are simultaneously excited to increase the bandwidth in the millimeter-waveband. The S-parameters, radiation patterns, antenna gains, and antenna efficiencies of the dual-frequency antennas are studied in detail. Reasonable agreement between the measured and simulated results is observed.