In recent years, the wireless LAN communication system's standard and technology has been widely used on a various field.
Dual-band pass filters have become important components for wireless LAN communication systems. Therefore, dual-band pass filter is essential for the development of wireless LAN communication systems.
Dual-band pass filters for wireless LAN operate at 2.4 GHz band of IEEE 802.11b/g and 5 GHz band of IEEE 802.11a.
Various kinds of dual-band pass filters have been studied and developed. However, design method of the existing dual-band pass filter is complex and its size is big.
In order to solve the above problem, in this paper, dual-band pass filter was designed by adjusting stopband via open stubs in compliance with the frequency bands of 2.4 GHz and 5.2 GHz, which enabled the dual-band operate of filter. In addition, the dual-band pass filter was highly miniatured by using open stubs. Furthermore, the dual-band pass filter was also designed by using step stubs for a further improvement of performance of the filter. The dual-band pass filter can be designed by adjusting the sizes of the step stubs in compliance with the frequency bands of 2.4 GHz and 5.2 GHz, which has the improved performance compared with the existing dual-band pass filter.
Two types of the dual-band pass filters designed by proposed design method in this paper has been fabricated and measured. The measured results for the fabricated dual-band pass filters agreed well with the simulated ones, and hence, it was confirmed that the proposed design method of a dual-band pass filters for wireless LAN is available.
Above results indicates that the proposed filter is a promising candidate for application to dual-band operate.