Enhanced High Gain Planar Endfire Dipole Antenna Using Third Higher Order

This paper presents an enhanced endfire antenna that combines a compact size and low-profile structure with high radiation performance. The antenna utilizes the third Higher Order Mode (HOM) of a Planar Dipole Antenna (PDA) in an endfire configuration to achieve significant gain enhancement compared to traditional planar endfire implementations. Unlike standard designs where the ground plane functions primarily as a passive reflector, the proposed approach redefines the ground plane as an active radiating component, effectively operating as a secondary dipole that contributes directly to the overall radiation. By optimizing the phase difference and spatial separation between the primary and secondary dipole elements, the design forms an endfire array configuration. The endfire radiation is further enhanced by exciting both dipoles in their third HOM, resulting in a peak gain of 9.14 dBi and radiation efficiency exceeding 98.5%. This high performance is achieved within a fully planar, balun-free, via-less architecture with compact dimensions of 1.24λ0 ×0.54λ0. The proposed design is also integrated as a driven element in a quasi-Yagi configuration, demonstrating its adaptability and offering an innovative solution for gain enhancement. By incorporating only a single-stage director pair, the antenna achieves a significant gain improvement over conventional planar quasi-Yagi configurations, reaching a peak gain of 11.32 dBi with a compact size of only 1.16λ0 × 0.773λ0. Experimental measurements from the fabricated prototypes closely match simulation results, validating the effectiveness of the gain enhancement approach and highlighting its potential as an innovative solution for compact, high gain planar antenna applications. This makes it particularly suitable for advanced wireless systems, including vehicular communication networks, fifth generation (5G) infrastructure, point-to-point (P2P) microwave links, ground-penetrating radar (GPR), and Internet of Things (IoT) platforms.