An experimental study on the resonant frequency of shorted elliptical patch Manidipa Nath (1) , T. Chakravarty (2)* & Asok De (3) * 1. SAMEER,Plot-L2, Block-GP, Sector-5, Salt Lake, Kolkata-700091 2. Future Institute of Engineering & Management, Sonarpur Station Road, Kolkata – 700150. Email: tap_chak@vsnl.net 3. Delhi College of Engineering, Sahabad, Daulatpur, Bawana Road, Delhi – 110042 Email: asokde@mail.com I. Introduction In this paper, a parametric study on the resonant frequency of shorted elliptical microstrip antenna is presented. A feed probe is located off-axis to generate closely spaced dual resonances for weakly elliptical patch. Using multiple shorting posts, the resonant frequencies of these modes are selectively tuned. Measured results are compared with simulation studies (IE3D) for validation. These results are presented. It is shown that such resonators have potential to operate as compact and tunable antenna Considering the present challenges in a microstrip antenna design, small impedance bandwidth in a microstrip antenna is an area where new techniques are evolved. A number of procedures have evolved over the years, which display an increase in bandwidth [1,2]. For increasing the effective bandwidth, a microstrip antenna of a small instantaneous bandwidth is electronically tuned over a large frequency range. For a fixed dimension of a microstrip antenna tunability can be obtained by connecting a variable reactive load to the patch. One particular method of varying the reactive loading is by changing the number or positions of the shorting posts. When the shorting post is placed between the patch and the ground plane, it changes the field distribution and provides inductive loading to the patch and hence changes its resonance frequency. In [3], a shorted annular elliptical patch is presented for GPS applications. Circular polarization is achieved with single feed. The characteristics of SAEP (shorted annular elliptical patch) is presented, where Mathiew functions have been approximated by Bessel function for weakly elliptical structure. In a recent article [4], study of surface wave emissions for SAEP are presented. The radiator consists of annular elliptical patch with inner border shorted to ground. To validate the results both numerical simulations and measurements are presented. In both the above mentioned works, annular shorted elliptical patch and its characteristics are studied. In the following sections, studies on elliptical patch with multiple shorts located in off-centred positions are presented. An elliptical patch loaded with multiple shorts has not been presented before in literature. The effort has been to study the impact of shorts on the resonant frequencies, thereby generalizing the potentiality of application areas . 1-4244-0123-2/06/$20.00 ©2006 IEEE 1469