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A compact microstrip dual-mode dual-band bandpass filter is presented. The filter consists of two E-shaped resonators and two T-shaped feedlines. By utilising the odd-mode and even-mode resonance properties of the proposed E-shaped resonator, the new filter is designed with two transmission poles in both passbands. Furthermore, the introduced two T-shaped feedlines and a coupling between them can result in multi-transmission zeros in the stopband, which will improve the selectivity of the filter. To validate the design theory, a dual-mode dual-band filter with two passbands located at the centre frequencies of 1.8 and 2.4 GHz, respectively, were designed and fabricated. Both experimental and simulation results are provided, with good agreement. [ABSTRACT FROM AUTHOR]

A compact microstrip lowpass filter with an ultra-wide stopband is proposed. To achieve wide stopband suppression and compact size, both symmetrically loaded resonant patches and meander transmission line are adopted. A demonstration filter with 3 dB cutoff frequency at 1.3 GHz has been designed, fabricated and measured. The proposed filter also exhibits a very wide stopband of 152%, and is able to suppress the eleventh-harmonic response together with a small size of 0.12λg × 0.071λg, where λg is the guided wavelength at 1.3 GHz. [ABSTRACT FROM AUTHOR]

A novel miniaturised microstrip lowpass filter has been studied. With triangular and high–low impedance resonators symmetrically loaded, the proposed filter has successfully achieved size reduction and performance enhancement simultaneously. A demonstrator filter with 3 dB cutoff frequency at 1.5 GHz has been designed, fabricated and measured. Results show that a roll-off of 257 dB/GHz together with a relative stopband bandwidth of 157.4% can be obtained while achieving a high figure-of-merit of 38747. [ABSTRACT FROM AUTHOR]