Investigation on Resonance and Radiation Properties of Rectangular Microstrip Antennas with Partially Filled Metamaterial Substrates and Superstrates Rowdra Ghatak, 1 Chiranjib Goswami, 2 Dipak Ranjan Poddar 3 1 Microwave and Antenna Research Laboratory, Department of ECE, National Institute of Technology Durgapur, West Bengal, India 2 Department of AEIE, Asansol Engineering College, West Bengal, India 3 Department of E & TCE, Jadavpur University, Kolkata, West Bengal, India Received 1 July 2011; accepted 31 January 2012 ABSTRACT: In this article, the effect on the resonance and radiation characteristics of a rectangular microstrip patch antenna partially loaded with inhomogeneous substrates and superstrates consisting of l-negative (MNG) and double-negative (DNG) metamaterials are investigated. It is observed that the size of the DNG and MNG material regions of the sub- strate influences the antenna gain and can be used to tune the resonant frequency as well as the bandwidth. Embedded DNG substrate blocks placed on either side of the radiating edge of the antenna results in increasing the gain to about 10 dBi and in dual-band resonance characteristics. Embedded MNG substrate resulted in gain enhancement to about 9.50 dBi. DNG materials used as superstrates result in dual-band operation with similar gain in both bands, whereas a MNG superstrate leads to improved impedance bandwidth. Moreover, dual-band characteristics can be achieved with almost the same realized peak gain in both bands, by using an optimum proportion of MNG and DNG materials as substrate. V C 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 00:000–000, 2012. Keywords: metamaterials; dispersive media; microstrip antennas I. INTRODUCTION Ever increasing requirement of compact antenna with high gain and wide bandwidth in wireless communication has put lot of challenges to antenna designers. Microstrip patch antennas are widely used, due to their low cost, low weight, low profile, and compact size. Some techniques reported to minimize planar antenna size are based on cut- ting slots on the surface of the patch [1], using shorting pins [2], and using high dielectric substrate materials, as well as thick substrates. Radiation efficiency and cross- polarization levels may degrade with the presence of these additional elements. The use of metamaterials (MTMs), properly tailored to miniaturize antenna size and improve parameters such as impedance matching, gain, bandwidth, efficiency, has been documented in [3]. Investigations on the use of MTMs for circuit size miniaturization and performance enhancement has acquired considerable importance in the last few years. These materials can be classified into: materials with negative real part of the permittivity (e-negative or ENG), negative real part of the permeability (l-negative or MNG) and materials having both these quantities negative (double-negative or DNG) in a given frequency range [4]. Ziolkowski proposed the usage of DNG MTMs to enhance radiation from electrically small antennas [5]. MTMs are also used to reduce the physical size of patch antennas [6–8]. The modified TM mode of a patch antenna loaded with double-positive (DPS)–MNG or DNG for dual-band application is reported in Ref. 9. It is demonstrated in Ref. 10 that a periodic arrangement of metallic split-ring resonators (SRRs) and wires can be modeled as a homogeneous macrostructure, provided that inclusion dimensions and separations are much smaller Correspondence to: R. Ghatak; e-mail: rowdraghatak@yahoo. com V C 2012 Wiley Periodicals, Inc. DOI 10.1002/mmce.20646 Published online in Wiley Online Library (wileyonlinelibrary.com). 1