Gain and Beamwidth Enhancement of SIW Sectoral Horn antenna for Ka-Band Application Abstract—Traditional H-plane sectoral horn antennas have flaring only in the direction of the H-field. As there is no flaring in the direction of the E-field, a fan-beam radiation characteristics is achievable from the H-plane sectoral horn antenna. Reduction of E-plane beamwidth is possible by placing parasitic elements like directors, reflectors at a proper distance from the radiating aperture of the SIW horn antenna that will lead to the improvement of E-plane beam-width as well as the antenna gain. In this communication, a novel multilayer H- plane sectoral horn antenna has been introduced for Ka-Band application with few attractive radiation characteristics like less beam-width in both principle plane, high gain, wide-bandwidth while maintaining low profile. In the proposed design, the dielectric substrate is extended in front of the radiating aperture and four vertical directors were placed by embedding metallic via hole at a proper distance from the radiating aperture. Also two rows of metallic via reflectors are placed at the back side of the radiating aperture to direct the radiated energy in the desired direction. Simulation result indicates that the proposed antenna maintains less E-plane and H-Plane beam-width and nearly constant peak radiating gain between 8 dBi to 11 dBi in end-fire direction along with a -10 dB impedance bandwidth of 1 GHz. Keywords—Beam-width Enhancement, Horn Antenna, Ka- Band Antenna, Millimeter Wave Antenna, Substrate integrated Waveguide. I. INTRODUCTION II. DESIGN AND ANALYSIS During the past decades, the vast amount of under used electromagnetic spectrum in millimeter wave frequency range has caught considerable interest among the researchers due to its capability to provide higher data rate and wider bandwidth for wireless devices. With the increase of frequency, the path-loss of electromagnetic waves increases dramatically [1]. Hence, high gain broadband antennas are in great demand for millimeter wave wireless communication. Horn antenna is one of the most promising structure for efficient transmission between a guided wave and free space wave propagation with a very high gain and a wideband impedance matching. With the invention of substrate integrated waveguide (SIW) technology, the implementation of the non-planar rectangular waveguide on existing planar printed circuit board and low temperature co- fired ceramics (LTCC) is possible. As the SIW have same electrical behavior with conventional rectangular waveguide, they became attractive for high-frequency application because it possess both the benefits of waveguides and the advantages of planar technology such as low profile, lightweight, and small size. SIW H-plane sectoral horn antennas can be easily implemented on PCB substrate, but these antennas are suffering from narrowband impedance matching because of its small radiating aperture. Several planar H-plane horn antennas have been reported in the literature [2-3]. The application of SIW for the design of integrated H-plane horn antennas are widely studied [4-5]. Dielectric-loading method was first proposed for improving the impedance matching [6]. In this technique, the extended dielectric serves as an impedance transformer and almost 10% impedance bandwidth was achieved. By placing air vias of different diameter in the extended substrates, a smooth transmission from waveguide to free space was achieved so that the impedance bandwidth could be expanded to 40% [7]. However the performance of this antenna is limited by the thickness of the substrates. In [8], a printed transition is introduced for a thin SIW horn antenna (thickness < λg/10) to solve the problem of mismatch. In the present work three layer of substrates have been used to implement the whole antenna system. The upper and lower layers consists of two rows of reflectors and the middle layer is used for implementing the horn antenna. In the middle layer, the dielectric substrate is extended by 6.5mm in front of radiating aperture to place the vertical directors for enhancing the E-plane beamwidth of the horn antenna. The details of the design is mentioned in the next section. Sourav Ghosh Soumava Mukherjee Department of Electrical Engineering Department of Electrical Engineering Indian Institute of Technology Jodhpur Indian Institute of Technology Jodhpur Jodhpur, India Jodhpur, India ghosh.3@iitj.ac.in soumava@iitj.ac.in The geometry of the proposed SIW H-plane sectoral horn antenna embedded with directors and reflectors is shown in Fig. 1. The antenna is implemented in three layers of dielectric substrate where upper and lower layers are used for implementing the two rows of vertical vias acting as reflectors. The middle layer consisting the H-plane sectoral horn antenna and four vertical directors has been implemented by embedding metallic via holes on the extended substrate in front of radiating aperture. The dielectric material used in the proposed SIW horn antenna is Rogers RT/Duroid-5880, with dielectric constant 2.2 and loss tangent of 0.0009 and having a thickness of 1.58mm in each layer. 2021 IEEE Indian Conference on Antennas and Propagation (InCAP) 978-1-6654-0110-4/21/$31.00 ©2021 IEEE 1016 2021 IEEE Indian Conference on Antennas and Propagation (InCAP) | 978-1-6654-0110-4/21/$31.00 ©2021 IEEE | DOI: 10.1109/INCAP52216.2021.9726480 Authorized licensed use limited to: Indian Institute of Technology - Jodhpur. Downloaded on December 22,2023 at 17:52:58 UTC from IEEE Xplore. Restrictions apply.