Design, Analysis and Fabrication of an Inside-Grooved Slotted Waveguide Array Antenna for HPM Applications

In this paper, a slotted waveguide array antenna (SWAA) is designed for S-band high-power microwave (HPM) applications. The single element of the array consists of ten Gaussian distributed slots on the broad wall of the waveguide, integrated with inside grooves. The 4-element SWAA configuration is designed to achieve a relatively high gain (24.6 dB) along with highly isolated (−24 dB) radiating elements. The gain enhancement and mutual coupling (MC) reduction is achieved by optimizing inside-grooved regions. An efficient $1\times 4$ power divider (PD) of identical phase and magnitude (−6 dB) at its output ports, is designed to feed the array elements. The radiation performance of SWAA is further improved by developing a dielectric radome. The proposed design is compact having dimensions $8.46\lambda _{0}\times 4.3\lambda _{0}\times 1.47\lambda _{0}$ , and offers return loss (RL) better than −25 dB with side lobe level (SLL) of −15 dB and −20 dB in E and H-plane, respectively. The designed array has 95.78% antenna efficiency over 3.8% measured bandwidth with 63% aperture efficiency. It has been demonstrated that the developed system, because of effective suppression of unwanted surface current, provides ±22° beam scanning without causing a significant reduction in its gain. The technique, without adding any complexity in the system, offered a 7% improvement in the gain when compared with a similar design.