International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 08 | Aug 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 599 A Novel Circularly Polarized Conformal Patch Antenna using Asymmetrically Slotted Ground Sumanta Kumar Kundu 1 , P K Singhal 2 1 ECE Deptt, Maharaja Agrasen Institute of Technology, New Delhi, India 2 Electronics Deptt, Madhav Institute of Technology, Gwalior, M.P. India. ---------------------------------------------------------------------***---------------------------------------------------------------------- Abstract - A single layer low profile circularly polarized conformal patch antenna utilizing asymmetrical circular slots at the ground plane is proposed. At first the planar antenna with slotted ground plane is designed. Using the same slot’s dimension in the ground plane, the simple square patch is embedded in cylindrically curved structure. At a particular radius of curvature, the antenna showing good result. A simulated 3 dB axial-ratio (AR) bandwidth of around 14 MHz with 54 MHz impedance bandwidth were achieved for planar antenna. The cylindrical curved patch antenna has good impedance band width of 76 MHz and 3 dB axial ratio band width 11 MHz. The 3 dB AR beam width for planar and curved patch antenna 138 degree & 148 degree and 84.2 degree & 58.6 degree in E plane and H plane respectively. The simulated bore sight gain for planar and cylindrical curved antenna are more than 2.89 dBic and 3.12 dBic respectively over the operating band. Key Words: Circularly polarized square Patch Antenna, Coaxial Feed, Impedance mismatch Bandwidth, conformal Antenna, Axial Ratio (AR). 1. INTRODUCTION Conformal microstrip antennas have been extensively studied and employed in a variety of communication systems [1-2]. Despite the inherent disadvantages of low bandwidth, medium or low gain, the conformability of these antennas to host surfaces makes them a obvious choice for varied communication applications [1-2]. This 1.9 GHz band is used to support the extension to serve the cordless telephone. In 2005, in India, this band was allocated for cordless telephone. Circular polarization becomes a need for patch radiator where there may be chances of problem of orientation mismatch between transmitter and receiver [3]. Circular polarization is obtained by the resultant of two linear polarized wave of 90 degree apart. The 90 degree phase shift can be achieved either by singly fed with perturbation in the structure and feeding in diagonal or doubly fed to the patch [3-9]. Another method for obtaining circular polarization by perturbing the structure either in patch or ground plane which produces two orthogonal modes[3-9]. In [6], A singly fed CP antenna is presented with slotted ground plane. Four asymmetric square slots are embedded on the ground and four rectangular slits are etched at the edge centre of the patch for the production of circular polarization [6]. The simulated maximum AR bandwidth (0.938 %,), and impedance bandwidth (4.886 %) were obtained using FR-4 material in [6]. In this article, the interesting thing to produce circular polarization is that, the way to make asymmetric slot placed asymmetrically in the ground plane. The main aim of this paper is to obtain circular polarization in conformal cylindrical patch [10-14] exactly in the same way as that of planar patch. Both the patch antenna on planar structure as well as on cylindrical structure are designed and simulated in CST microwave studio [15] 2 PLANAR ANTENNA DESIGN A top and bottom view of proposed patch antenna is shown indicated in fig 1. The dimensions of simple patch antenna 34.84 mm x 34.84 mm with ground plane of 46.91 mm x 46.91 mm are designed. The feed is placed along Y axis at the point (-6 mm, 0). Two asymmetrical slots are etched on the ground plane placed asymmetrically for the production of circular polarisation. Fig 1. Simple planar patch [12-14] 2.1 Variation of bigger and smaller slots in the ground plane: Initially the slots were etched at 6.66 mm and -1.04 mm away from the centre along the diagonal [7-8]. At first, the radius of bigger slot is varied and the result is observed in term of S11, AR, and frequency keeping remaining dimension of the patch, and bigger slots etc fixed. The best AR, S11 are obtained at a optimized dimension of bigger radius 5.07 mm shown in fig 2 (a-b). The circular polarization is being