A novel design of miniature filter-antenna with broad stop-band characteristic

A new miniature micro-strip filter-antenna with broad stop-band characteristic is designed in this paper. The filter-antenna consists of two SIR (stepped impedance resonators), parallel coupled line and inverter L-shaped antenna. The antenna plays role of not only a radiator, but also one resonator of the filter. The SIR gives a way to control spurious response frequency which leads to a wide stop-band. And length of SIR is smaller than UIR (Uniform impedance resonator) in the same resonant frequency which can reduce the size of the filter-antenna. The filter-antenna has been simulated by HFSS.17. The results show that the filter-antenna has about 8% (2.36-2.55GHz) fractional bandwidth in condition that S11<;10dB, and the gain in band is about 1.8dBi. The stop-band reaches to 7.8GHz and the gain in stop-band is less -18dBi. The size of this SIR filter-antenna is about 0.26λ
_g
, × 0.5λ
_g
, which is much less than UIR filter-antenna.