A novel open-loop dumbbell-shaped DGS bandpass unit is proposed and it has a property of quasi-elliptic bandpass characteristic. The two transmission zeros bounding the passband can be easily controlled by the open-loop edge ength and open-end location. With a DGS unit alone, a 3-order quasi-elliptic bandpass response can be achieved and it offers better band edge skirt and smaller circuitry size than the conventional DGS bandpass filter. From the simulatedand measured results of the bandpass filter using two DGS units, the passband characteristic matches the 5-order quasielliptic mathematical model. Moreover, this filter can alsoprovide a 20-dB wide upper stopband upto 6 times of center frequency.
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