A compact dual-band band-pass filter is proposed in this paper. The central frequencies of the passbands are around 2.46 GHz and 5.86 GHz. There are two resonators located at the top side layer and the bottom side(the CPW) layer, respectively. Dual-resonance operation usually needs two resonators on the same layer to generate two passbands simultaneously. However,in this paper the size can be reduced efficiently by connecting resonators at two layers through via-holes to implement dual-band performance. Furthermore, the stop-band for this novel filter with T slot-line, L-line and rectangular micro-strips can be extended to 30 GHz. To verify the feasibility of the design above, a dual-band band-pass filter has been implemented on a Rogers RT5880 substrate (thickness is 0.508 mm). This filter with passbands operated at 2.46 GHz and 5.86 GHz can finely meet the IEEE 802.11 n wireless local area network (WLAN) bands requirements.
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