Multiband Quasi-Yagi Antenna with Frequency-Selective Multi-Branch Directors for Sub-6 GHz Applications

This paper presents a novel design of a high-gain, low-profile multiband quasi-Yagi antenna. The proposed antenna will operate in the 2.45 GHz, 3.60 GHz, and 5.80 GHz frequency bands. The proposed antenna consists of a primary driven dipole printed on the sides of a substrate, two parasitic elements, and a new branch line director. The main dipole element is utilized to generate the first frequency band. The two parasitic elements added near the driven dipole excite the last two frequency bands. The proposed antenna is appropriate for multiband applications due to its directional radiation patterns and front-to-back ratios, which exceed 13.4 dB for all frequency operating bands. The single-branch line director antenna realizes gains of 6.7, 7.5, and 7.4 dBi at 2.45, 3.6, and 5.8 GHz, respectively. When the number of branch line directors increases, the antenna's gain increases over all the operating frequency bands. The realized gains with five branch line directors are 10.1, 11.8, and 11.9 dBi at 2.45, 3.6, and 5.8 GHz, respectively. Moreover, a 2 × 1 MIMO configuration is also demonstrated, achieving inter-element isolation greater than 20 dB at 2.45 GHz and 30 dB at 3.60 and 5.80 GHz, confirming the antenna's suitability for 5G, Wi-Fi, and IoT sub-6 GHz applications.