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 TE
^x
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 TE
^x
₁₁₁
and TE
^x
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.