IJSART - Volume 4 Issue 3 – MARCH 2018 ISSN [ONLINE]: 2395-1052 Page | 948 www.ijsart.com Substrate Integrated Waveguide Cavity-Backed Ku- Band Slot Antennas With Shorting Vias Dr. S. Anand 1 , R.Palanichamy 2 , Fx.Joshua Paul Ebenezer 3 1,2,3 Dept of Electronics & Communication Engineering 1,2,3 Mepco Schlenk Engineering College, Sivakasi Abstract- A substrate integrated waveguide (SIW) cavity- backed slot Ku-band antennas using shorting vias is presented in this paper. The antenna has wide bandwidth and low profiles. By loading the SIW cavity with shorting vias and substrate value and material is changed. So as a result, a wide bandwidth with cavity-backed slot antenna is achieved. Based on the similar principle, a cavity-backed slot antenna having an even wider bandwidth is also developed. Prototypes of the antenna is measured. With a low profile of 0.03λ (wavelength in free space), the cavity-backed slot antenna design has a bandwidth efficiency of 21.04% and a peak gain of 6.884dBi. Keywords- Cavity-backed slot antenna, shorting vias, substrate integrated waveguide (SIW), wideband. I. INTRODUCTION SUBSTRATE integrated waveguide (SIW) cavity- backed slot antenna shows outstanding advantages (such as light weight, low profile, and easy integration with planar circuits) in microwave systems. However, due to the high- quality factor and quad-resonance response, conventional SIW cavity-backed slot antennas, limiting their applications in wideband communication systems. Recently, works have been presented in the literature [1] for enhancing the bandwidths of SIW cavity backed slot antenna. In [2] the bandwidth was increased up to 2.18% by partial removal of the substrate. However, the bandwidth enhancement was limited because the design only utilized a single slot mode. Using additional resonant patch, some wideband multimode mode SIW cavity backed slot antenna were developed. In, a wideband SIW cavity-backed patch antenna was proposed, in which an additional patch mode was existed. In [3], a dual-resonance slot-patch structure composed of a half-wavelength slot and a parasitic patch was employed for bandwidth enhancement. In [4], a wideband dual mode design using triangular complimentary split ring slot (TCSRS)achieved bandwidth of 21.04%. Several dual-band SIW cavity backed slot antenna were also realized with specific slot shapes (e.g., dumbbell-shaped slot [5], dual rectangular slot [6]). In, by dividing an SIW cavity into two half parts with a non- resonant rectangular slot, two hybrid cavity modes were excited, and the fractional bandwidth could be improved up to6.3%. Based on the similar principle, the SIW cavity antenna in achieved a wider bandwidth of 9.4% using a bowtie shaped slot. In, a SIW cavity-backed 3 × 3 slot array antenna was studied. Three high-order cavity modes along with the slot mode were utilized in this design, leading to a bandwidth over 26%. Previously, shorting vias were introduced in SIW based feeding networks for improving the impedance matching of the cavity-backed slot antenna. In, a dual- resonance SIW cavity-backed slot antenna was realized using a via hole above the slot. Nevertheless, the bandwidth of the antenna in was comparatively narrow (3.3%). Shorting vias were also used in SIW filters, SIW frequency selective surface, and patch antenna for bandwidth enhancement. In [5] this paper, we propose single wideband SIW cavity-backed slot antenna using shorting vias. The antenna has cavity backed slot in their operation bands, respectively. With the shorting vias loading, the lowest mode in the SIW cavity is shifted upward and coupled with two higher order modes. Therefore, a wide bandwidth with cavity backed slot is realized. The cavity backed slot antenna has a very low profile of 0.03λand a measured bandwidth of 21.04%. The antenna has stable radiation patterns and flat gains in their operation bands. II. CAVITY-BACKED SLOTANTENNA A. Geometry Fig. 1 shows the geometry of the proposed cavity- backed Ku-band slot antenna. The antenna is constructed on a single-layer substrate with a thickness of h and a relative permittivity of ɛr. Arrays of grounded vias are uniformly distributed along the edges of the antenna to build an SIW cavity. In order to avoid the energy leakage from the via gaps, the diameter d and the spacing of the sidewall shorting vias are chosen to be d = 1mmand s = 1.5 mm, respectively, which satisfy the conditions of s/ɛd= 2andd/λ= 0.1. Another two shorting vias with the same diameter d and a spacing s0are inserted near the center of the SIW cavity. A rectangular slot