A Novel Yagi Element Integrated Nested Loop Quasi-Self-Complementary Dual-Port Combiner Radiator

This article presents a quasi-self-complementary radiator structure designed to operate simultaneously as a combiner and an antenna. The dual-port architecture comprises axially symmetric nested microstrip loops. The upper half of the radiator structure placed on the top plane is nearly complementary to the lower half on the bottom plane. The nested loop is loaded with a Yagi element for improved performance. This additional element in the radiator enhances the end-fire radiation from the nested loop wideband dual port structure without disturbing the parallel combiner action. An additional gain of nearly 3 dB is obtained with this element across the operating bandwidth. Measurement of both the fabricated prototypes, with and without the Yagi element, reveal the desired parallel combiner action for an operating range of 1.8-2.3 GHz with good matching. The quasi-self-complementary nested loop architecture offers a wide operational bandwidth. The proposed radiator structure is a compact and low-loss alternative for antenna arrays.