Electronically switchable and reconfigurable microwave devices such as filters are in great demand for wireless communication
systems. The switchable Lowpass/Bandpass filter (LPF/BPF) can be used to control the spectrum of proposed signals and support
multiple information channels. The PIN diodes are used to achieve exchange between the lowpass filter and bandpass filter with
tunable bandwidth. The lowpass filter concept is demonstrated by ninth-order Chebyshev-type using stepped impedance resonators. as
the number of diodes used increase as the roll off at the two 3dB frequency for bandpass is modified, with a little decrease in the bandwidth
due to the shift of lower 3dB frequency to higher value, while the upper 3-dB frequency is nearly remain constant around 11 GHz.
The switchable LPF/BPF is designed, fabricated and measured. Experimental results are in good agreement with the simulated results
for each of the lowpass and bandpass filters response. |
