Progress In Electromagnetics Research C, Vol. 111, 61–72, 2021 Gain Enhancement of SIW Cavity-Backed Antenna Using Dielectric Loading Dhara M. Patel * and Falguni Raval Abstract—This article presents the design and development of a low proﬁle substrate integrated waveguide semi-circular cavity-backed antenna loaded with dielectric cylinders of glass-reinforced epoxy and Teﬂon. The substrate integrated waveguide semi-circular cavity-backed antenna without dielectric loading radiates at 5.8 GHz with 3.13 dB gain. The antenna is modiﬁed by putting dielectric cylinders of diﬀerent materials and diﬀerent sizes at the edge of a semi-circular cavity to enhance the gain of the antenna. The new antenna thus created has improved gain of 8.13 dB. All simulations are done using high frequency structure simulation software. The proposed design is fabricated on a glass-reinforced epoxy substrate with a semi-circular cavity having a size of 60 mm × 50 mm. The measured results are in good agreement with simulated ones. 1. INTRODUCTION In recent years, the antennas having low-proﬁle and large bandwidth, high gain, and good radiation are in high demand for advanced wireless communications. The rapid development of wireless communication systems needs antennas with a good radiation pattern and high-performance parameters including low proﬁle, low cost, light weight, easy fabrication, and smooth integration with planar circuits [1– 4]. Microstrip slots antennas are best suitable for above applications; however, they suﬀer from low forward gain and radiation eﬃciency due to conductor losses and bidirectional radiation. To overcome these disadvantages and improve gain and radiation eﬃciency, a metallic reﬂector or cavity backed antennas [5,6] were introduced. However, metallic antennas and cavity-backed antennas are massively heavy, and high fabrication costs make them not suitable for some applications in satellite, aircraft, and high-density microwave communication systems [7]. The substrate integrated waveguide (SIW) technology was applied to cavity backed slot antennas to eradicate the above-mentioned drawbacks [8]. Recently, some solutions aimed at enhancing the gain of SIW cavity antennas have been investigated. In [9], to enhance antenna gain, high order of cavity resonance TE 220 is used. In [10], three parallel transverse slots were created on back of the antenna, used higher resonance TE 410 mode to enhance the gain parameters, and these slots acted as radiating elements. In [11], a compact and light weight SIW antenna was reported. To improve gain a horn mounted cylindrical dielectric resonator was used. In [12], a dual-polarized SIW cavity backed slot antenna was reported, and the antenna gain was enhanced by using a higher order cavity resonance to generate arbitrary levels of inclined linear polarization having metal posts embedded in main cavity. In this paper, a half-mode semicircular cavity backed antenna is presented. Further, to enhance the antenna gain, the design of a semicircular cavity backed antenna is modiﬁed using two parallel stacks of dielectric cylinders of diﬀerent sizes and diﬀerent materials. Teﬂon and FR4 are used as dielectric materials. The systematic design analysis of cavity backed antennas with dielectric cylinders is represented in Section 2 followed by the comparative analysis between simulated and measured parameters of the proposed antenna. Received 19 January 2021, Accepted 10 March 2021, Scheduled 18 March 2021 * Corresponding author: Dhara Milan Patel (dharampatel.ec@charusat.ac.in). The authors are with the V. T. Patel Department of Electronics and Communication Engineering, C S Patel Institute of Technology, Charotar University of Science and Technology, India.