Effect of Curvature on a Microstrip Printed Antenna Conformed on Cylindrical Body at Superhigh Frequencies Ali Elrashidi 1 , Khaled Elleithy 2 , Hassan Bajwa 3 1 Department of Computer and Electrical Engineering, University of Bridgeport, Bridgeport, CT 06604, USA (aelrashi@bridgeport.edu) 2Department of Computer and Electrical Engineering, University of Bridgeport, Bridgeport, CT 06604, USA (elleithy@bridgeport.edu) 3Department of Computer and Electrical Engineering, University of Bridgeport, Bridgeport, CT 06604, USA (hbjwa@bridgeport.edu) Abstract- Curvature has a great effect on fringing field of a microstrip antenna and consequently fringing field affects effective dielectric constant and then all antenna parameters. A new mathematical model for input impedance, return loss, voltage standing wave ratio and electric and magnetic fields is introduced in this paper. These parameters are given TM 10 mode and RT/duroid-5880 PTFE substrate material. The introduced model is valid at superhigh frequency range (3– 30 GHz). Keywords: Fringing field, Curvature, effective dielectric constant and Return loss (S11), Voltage Standing Wave Ratio (VSWR), Transverse Magnetic TM 10 and TM 01 modes. 1. Introduction Due to the unprinted growth in wireless applications and increasing demand of low cost solutions for RF and microwave communication systems, the microstrip flat antenna, has undergone tremendous growth recently. Though the models used in analyzing microstrip structures have been widely accepted, the effect of curvature on dielectric constant and antenna performance has not been studied in detail. Low profile, low weight, low cost and its ability of conforming to curve surfaces [1], conformal microstrip structures have also witnessed enormous growth in the last few years. Applications of microstrip structures include Unmanned Aerial Vehicle (UAV), planes, rocket, radars and communication industry [2]. Some advantages of conformal antennas over the planer microstrip structure include, easy installation (randome not needed), capability of embedded structure within composite aerodynamic surfaces, better angular coverage and controlled gain, depending upon shape [3, 4]. While Conformal Antenna provide potential solution for many applications, it has some drawbacks due to bedding [5]. Such drawbacks include phase, impedance, and resonance frequency errors due to the stretching and compression of the dielectric material along the inner and outer surfaces of conformal surface. Changes in the dielectric constant and material thickness also affect the performance of the antenna. Analysis tools for conformal arrays are not mature and fully developed [6]. Dielectric materials suffer from cracking due to bending and that will affect the performance of the conformal microstrip antenna. 2. Background Conventional microstrip antenna has a metallic patch printed on a thin, grounded dielectric substrate. Although the patch can be of any shape, rectangular patches, as shown in Figure 1 [7], are preferred due to easy calculation and modeling. Fringing fields have a great effect on the performance of a microstrip antenna. In microstrip antennas the electric filed in the center of the patch is zero. The radiation is due to the fringing field between the periphery of the patch and the ground plane. For the rectangular patch shown in the Figure 2, there is no field variation along the width and thickness. The amount of the fringing field is a function of the dimensions of the patch and the height of the substrate. Higher the substrate, the greater is the fringing field. Figure. 1. Rectangular microstrip antenna L W ɛ r