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


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 First, the edges of the conventional square patch have been replaced by first iteration Koch pre-fractal curves.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 IE3DTM 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.