A seven-band co-integrated antenna for 5G/6G operations in sub-6 GHz and millimeter-wave frequencies

The use of millimeter-wave (mmWave) frequencies is increasing to meet the broader application needs of modern civilization. These bands are essential in 5G and beyond (Next-G) communication systems to provide wide bandwidth and high data rates. However, it is highly unlikely that the sub-6 GHz bands will be decommissioned anytime soon because of their long-range coverage and high-speed connectivity. Therefore, mmWave and sub-6 GHz antennas and radio frequency (RF) front ends must be integrated into the same system in modern radio designs. Placing various antennas on a single platform is challenging because of the different sizes of the radiating elements that correspond to a wide range of frequencies. To avoid higher-order mode coupling, high isolation is achieved by properly optimizing the placement of each aperture. In this work, we present a co-integrated shared-aperture antenna system capable of operating at seven frequency bands from 600 MHz to 39 GHz, covering both sub-6 GHz and mmWave spectra. Sub-6 GHz operation is achieved using four inverted-L antennas and a slotted patch covering 600 MHz to 6 GHz, while two 4×4 patch arrays are used at 28 GHz and 39 GHz for mmWave. A fabricated prototype demonstrates excellent agreement between measured and simulated results, with consistently low crosstalk (typically below -20 dB), stable realized gain, and compact overall size (200 mm × 85 mm). The proposed design ensures broad frequency coverage and compact integration, making it suitable for 5G/6G, satellite, vehicular, fixed wireless access, IAB, and defense applications requiring multi-band connectivity.