Proceedings of IEEE 2008 6th National Conference on Telecommunication Technologies and IEEE 2008 2nd Malaysia Conference on Photonics, 26-27 August 2008, Putrajaya, Malaysia Circuit Element Modeling Scheme for a Hairpin Resonator by Using EDA Tool Goh Chin Hock, Sanjay Devkumar, Mohammad Hadi Badjian and Chandan Kumar Chakrabarty Department of Electronics and Communication Engineering, Universiti Tenaga Nasional Selangor Darul Ehsan, Malaysia chinhockgunitenedm; sanl y@unitenx t; mhadicuniten.edu.my; chandanguniternedumy Abstract-This paper describes how a circuit element modeling scheme was used to analyze and optimize a microstrip open loop resonator. With the discrete optimization, realistic values can be assigned to the designed resonator. The circuit element models of the open loop resonator represent the structure very well with respect to electromagnetic models. Besides that, it provides a fine computation speed of simulation to study the resonator. The understanding and intuition of particular segment of the structure is very helpful and valuable for the designers to make the initial estimation. Keywords-analytical element model; open loop resonator; discrete optimization; capacitive coupled structure I. INTRODUCTION The electromagnetic spectrum is limited and has to be shared. Thus, emerging wireless communication system has continued to challenge microwave filter with ever more stringent constraint and particular specification. Microwave filters were designed with higher performance, smaller dimension, lighter weight and lower cost in order to meet the market needs. As the resonators are the basic structure blocks of microwave filters, numerous studies were performed by researchers. Due to the advantages of small dimension and ease of fabrication, microstrip hairpin resonator has been widely investigated. From the conventional hairpin resonator to proposed capacitive coupled structure and stepped impedance hairpin resonator, size reduction has been significantly achieved [1-2]. Besides that, the first spurious response has been shifted to higher frequency band in order to have larger bandwidth of stopband. Numerous configurations of miniaturized hairpin resonators and stepped impedance resonators were proposed. Figure 1 shows the various type of hairpin resonator has been proposed. They have been described by using odd and even mode as well as network models in term of ABCD matrix [3-6]. Besides that, some resonator configurations include with valuable circuit design implementation such as equivalent lumped element circuits. However, microwave resonator realization can be challenging as the values maybe assigned with unrealistic value. Moreover, the resonator might difficult to be fabricated as the size do not meet the specification of the printed circuit board technology as shown in Table I. In this paper, circuit element modeling scheme is used to design and analyzed the microstrip open loop resonator. The open loop resonator is segmented into two parts in order to study the characteristic of the capacitive coupled transmission line. Useful information about the effect of the dimension change is provided. Figure 1. Various of type of hairpin open loop resonator TABLE I. TYPICAL TRACE WIDTH, SPACE AND PAD SIZE All Dimension in Inches Type Minimum metal width and space Minimum pad size A 0.010 0.021 B 0.008 0.021 C 0.006 0.016 D 0.005 0.013 E 0.004 0.013 II. ELEMENT MODELS FOR OPEN LOOP RESONATOR A conventional open loop hairpin resonator is modeled with circuit element modeling scheme by using linear circuit simulator. The modeling scheme is using EM quasi-static model [7] that is heavily relies on the involved numerical algorithms. Vector variables are defined for each parameter that will be discretely optimized. Three hairpin resonators with different feeding configuration are represented with element models and analyzed with linear circuit simulator. Figure 2 shows the element models for the hairpin resonator type A. Simulation response of the discretely optimized [8] open loop resonator is shown in Figure 3 and 4. The simulation change on the graph can be observed as the variables are tuned and optimized. Table II shows the s-parameter of the discretely 978-1-4244-2215-9/08/$25.00 ©2008 IEEE. 170