Self-diplexing Antenna Operating at Sub-6 GHz and Millimeter-wave Frequency Bands

A low-profile self-diplexing antenna supporting sub-6 GHz and mm-wave frequencies is introduced for the first time. The design process starts with cutting a Substrate Integrated Waveguide (SIW) cavity into two equal parts. One part is taken into consideration for the proposed antenna in a way that a small part of the cavity is selected for mm-wave operation (28 GHz), and the rest is assigned for microwave operation (4.8 GHz). A capacitive slot brings the microwave frequency to the desired band (4.8 GHz). The mutual coupling among the ports is less than -30 dB and the measured gains show 5.3 and 8 dBi for low and high bands, respectively. It should be mentioned that independence of frequencies is another advantage of the proposed structure. Therefore, such an antenna is a suitable alternative for traditional dual-band antennas.