Frequency-reconfigurable aperture-coupled magneto-electric dipole antenna for multi-band sub-6 GHz 5G NR systems

This paper presents a compact, wideband, and frequency-reconfigurable Magneto-Electric Dipole (MED) antenna designed for sub-6 GHz 5G New Radio (NR) and Industrial, Scientific, and Medical (ISM)/ Wireless Local Area Network (WLAN) applications. The proposed antenna utilizes an aperture-coupled excitation mechanism integrated within a multilayer FR4 structure, featuring complementary electric and magnetic dipole elements that are optimized through a four-step evolutionary design process. The final configuration achieves a simulated broad Impedance Bandwidth (IBW) of 2.24-4.55 GHz in the all-diodes-off state, while maintaining stable broadside radiation, a peak gain of over 7.7 dBi, and a radiation efficiency of up to 94.2%. Frequency reconfigurability is achieved through the use of six strategically placed PIN diodes, which selectively modify the current distribution on the microstrip feed line by coupling six rectangular stubs. Multiple diode-controlled switching states enable wide tunability from 1.79 GHz to 4.41 GHz, providing support for more than twelve major 5G NR bands, including n7, n30, n34, n38, n40, n41, n48, n53, n65, n77, n78, n90, n95, and n97, as well as ISM/WLAN services. Simulated and measured results exhibit strong agreement across all states, with peak gains ranging from 7.06 to 7.82 dBi and radiation efficiencies between 65.6% and 96.1% (see Table 3), confirming the robustness of the aperture-coupled and diode-integrated MED architecture. Compared to recent state-of-the-art MED and reconfigurable MED antennas, the proposed design demonstrates a wider tuning range, competitive gain, and reduced structural complexity while maintaining a compact volume of 0.48λ₀ × 0.48λ₀ × 0.11λ₀ at 3.5 GHz. These characteristics highlight its suitability for compact 5G terminals, small-cell base stations, reconfigurable wireless systems, and multi-standard communication platforms.