Title :
Compact UWB bandpass filter on hybrid microstrip/slotline structure with improved out-of-band performances
Author :
Li, Rui ; Zhu, Lei
Author_Institution :
Sch. of Electr. & Electron. Eng., Nanyang Technol. Univ., Singapore
Abstract :
A compact ultra-wideband (UWB) bandpass filter with good in-band and out-of-band performances is proposed and implemented on hybrid microstrip/slotline structure. A multiple-mode slotline resonator with stepped-impedance configuration is first properly constructed, aiming to allocate its first three resonances occurring at desired positions within the UWB passband. Two 50 Omega microstrip feed lines are then placed perpendicular to this slotline resonator on the opposite side of the substrate. As a result, an initial back-to-back microstrip-slotline bandpass filter is constituted with the targeted UWB passband. Later the slotline resonator is twisted and an additional coupling between two open-ends of feed lines is introduced, resulting in miniaturizing its overall circuitry size and enhancing the roll-off skirts out of the passband. In final, defected ground structures (DGSs) are formed on the two feed lines to improve the upper stopband performance. Two UWB bandpass filters are designed, fabricated and measured. Measured results demonstrate an UWB passband from 3.25 to 10.21 GHz with in-band return loss >10.43 dB and group delay variation <0.34 ns.
Keywords :
band-pass filters; band-stop filters; cavity resonator filters; microstrip filters; microstrip lines; microstrip resonators; network synthesis; slot line components; substrates; UWB bandpass filter; defected ground structures; frequency 3.25 GHz to 10.21 GHz; group delay variation; hybrid microstrip-slotline structure; improved out-of- band performances; in-band return loss; microstrip feed lines; multiplemode slotline resonator; resistance 50 ohm; stepped-impedance configuration; ultrawideband bandpass filter; Band pass filters; Coupling circuits; Feeds; Loss measurement; Microstrip filters; Microstrip resonators; Passband; Resonance; Slotline; Ultra wideband technology;
Conference_Titel :
Microwave and Millimeter Wave Technology, 2008. ICMMT 2008. International Conference on
Conference_Location :
Nanjing
Print_ISBN :
978-1-4244-1879-4
Electronic_ISBN :
978-1-4244-1880-0
DOI :
10.1109/ICMMT.2008.4540286