Integration of SIW Directional Coupler and E-Plane Tee for Wideband Antenna using Hybrid of Rectangular and Ring Slots for X-Band Applications

Abstract

Advances in microwave technology and telecommunications have led to compact circuits, reduction of costs, masses and losses. The integration between microwave devices and components are considered a trend for microwave applications. The substrate integrated waveguide (SIW) technology has a great agreement with this trend in these applications. In this paper an integration of $-3 \mathrm{~dB}$ SIW directional coupler operating from 8.31 to 9.67 GHz with 90 degree phase shift at output ports and two series (E-plane) tee junctions operating from 8.8 to 12 GHz with 180 degree phase shift at output ports have been designed to feed 4-array of wideband hybrid slots including rectangular and ring shape slots with phase shifted signals. The wideband arrays consist of 64 rings and 16 rectangular slots distributed equally for the four arrays. The proposed integrated system has been designed and implemented using Roggers 4350 of $\varepsilon_{\mathrm{r}}=3.6, \tan \delta=0.004$ and thickness $h_{R}=1.5 \mathrm{~mm}$. The proposed integrated system has been simulated using HFSS simulator. The SIW system has an agreement between simulated and measured results. The SIW system introduces $S_{11}=-51 \mathrm{~dB}$, gain of 7.5 dB, radiation efficiency of 81.1% and fractional bandwidth of 15.7% for airborne insight, observation and surveillance (AISR) applications.