Design of a New Reduced Size Dual-Mode Microstrip Resonator Bandpass Filter for Modern Wireless Applications

Abstract

In this paper, the design of a new compact size dual-mode microstrip resonator is presented as a candidate for use in modern wireless applications. The proposed resonator structure is a result of applying two reduction techniques to the conventional square patch dual-mode microstrip resonator. First, the edges of the conventional square patch have been replaced by first iteration Koch pre-fractal curves. The proposed resonator filter has been designed for ISM band applications, at 2.4 GHz, using a substrate with a relative dielectric constant of 10.8 and thickness of 1.27 mm. This has shown to result in dual-mode resonator with a side length of 16.05 mm, which represents a size reduction of about 24%, as compared with the conventional square patch resonator using the same substrate and designed at the same frequency. Moreover, the resonator size has been further reduced by inserting a crossed slot in the patch structure. The resulting microstrip patch dual-mode resonator has been found to possess a side length of about 11.55 mm, which represents a size reduction of about 61% as compared with the conventional square patch dual-mode resonator. Modeling and performance evaluation of the presented resonator structures have been carried out using a method of moments based IE3D™™ SSD electromagnetic simulator from Mentor Graphics Corporation. Simulation results show that the proposed filter has acceptable return loss and transmission responses besides the miniaturized size gained.