Realization of a Compact Microstrip Antenna: An Optimization Approach Vibha Rani Gupta and Nisha Gupta Birla Institute of Technology, Mesra, Ranchi– 835215, India Received 23 February 2005; accepted 24 July 2005 ABSTRACT: A new compact square microstrip patch antenna is proposed using the optimi- zation approach, namely, the genetic algorithm (GA). The antenna is designed at three different frequencies, 785 MHz., 1.57 GHz, and 2.46 GHz, for mobile communication, GPS, and Bluetooth applications, respectively. The simulations are carried out using IE3D from Zeland Software, which is based on the method of moments (MoM). The antenna consists of a probe-fed truncated-corner square patch with four inserted slits along the four diagonals and four angular grooves along the four edges of the patch. The proposed design has a reduced antenna size, as compared to the conventional microstrip antenna at a given operating frequency. The return loss, impedance, and axial-ratio bandwidth are determined and com- pared with the conventional square-patch antenna. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE 16: 367–373, 2006. Keywords: compact microstrip antenna; size reduction; optimization; genetic algorithm I. INTRODUCTION Antenna design presents unique challenges in terms of size, cost, and performance, such as return loss, band- width, gain, and so forth. As a result, designers usu- ally take the approach of combining the full-wave technique used for EM analysis with the optimization technique. In particular, the genetic algorithm (GA) [1] has gained greater momentum in the field of EM optimization, as it can be suitably combined with a full-wave technique such as the method of moments (MoM) [2]. At the same time, it yields results that satisfy the given requirements in a nonintuitive fash- ion. With the advent of wireless technology and ever- increasing demand for high-data-rate wireless com- munication, small size of the antenna has become an important requirement for portable applications. Mi- crostrip antennas are being widely used for aerospace applications and in small portable wireless communi- cation equipment because of their compactness, light weight, low profile, and relative ease of fabrication. Rectangular, circular, and triangular patch shapes are commonly used patches. However, changing the basic shape can give rise to substantial size reduction. Several microstrip patch configurations have been studied in the past [3–7] for producing substantial size reduction using high-permittivity substrate, shorting pins, partially filled high-permittivity substrate, fractal configurations, and so on. In the present work, a new, compact, square, circularly-polarized microstrip patch antenna with four slits inserted along the four diago- nals and four angular grooves along the four edges of the patch is proposed. The genetic optimization tech- nique is used in the design. An IE3D EM simulator and optimization package is used in the design, which allows the users to define the shape of the patch antenna as optimization variables. The built-in opti- mizer is used to optimize the shape of the structure for Correspondence to: N. Gupta; email: ngupta@bitmesra.ac.in. DOI 10.1002/mmce.20157 Published online 3 April 2006 in Wiley InterScience (www. interscience.wiley.com). © 2006 Wiley Periodicals, Inc. 367