An ultra-compact VHF CRLH-line bandpass filter less than (λg/19)2 with a broad stopband

A VHF bandpass filter is designed to be extremely compact and working suitable for a lighter and high-fidelity T-DMB receiver. A super-small distributed element CRLH unit cell is devised based on the T-type equivalent circuit and the three blocks of the unit cell are cascaded by matching the neighboring impedances. Therefore, the overall footprint of the filter is less than (wavelength/19)x(wavelength/34), and the passband with low insertion- and return loss is obtained as demanded in the 180-MHz T-DMB service. Besides, this zeroth-order resonance filter shows an excellent performance of suppressing the spurious harmonics over a very broad stopband up to several GHz.