Novel SIR bandpass filter with compact coupling

Dual-band and tri-band SIR bandpass filters with compact coupling and sizes reduction are proposed, and two paths coupling is introduced. In the new design, split ring SIR and DGS techniques are applied to not only reduce the size but also improve the filter frequency responses. The presented filters have advantages of compact and novel structures, smaller sizes compared to the traditional SIR bandpass filters, and nicer performances such as high selectivity, low passband insertion losses and so on, and all these can be quite useful in wireless communication systems.