Design of a Compact Dual-Band Bandpass Filter Using Opposite Hook-Shaped Resonator

In this letter, a compact dual-band bandpass filter is presented for wireless area networks (WLAN) operations. The filter, which is only 0.04 λ0× 0.09λ0in overall dimensions, is composed of two symmetric parts. In each part, two opposite hook-shaped strips with different resonant paths are used to achieve the dual-band operation at 2.4 and 5.8 GHz, with 19.54% and 15.12% fractional bandwidth, respectively. The central frequencies of the two passbands can be controlled independently by adjusting dimensions of the hooks. To verify the proposed idea, a prototype is implemented, and the measurement results agree well with the full-wave electromagnetic simulated responses.