Abstract
In this paper miniaturized quarter wavelength rectangular shaped multimode ring resonator bandpass filter with extended diagonal corners and internally located high impedance perturbation stubs, is proposed. Input/output open stubs are tightly coupled to the extended diagonal corners running parallel to the two sides of the ring resonator, implemented to generate wide passband and wide stop-band. Cut-off frequencies can be shifted to the higher side by increasing the length of the sides of resonator. By inserting the perturbation stubs, rectangular ring resonator produces three degenerate modes out of which first two form a wide passband. Small square patch is attached to the opposite interior corners of the ring resonator and T-shaped stub attached to the opposite longer side of the resonator are tightly coupled with feeder line to improve the return loss, insertion loss and skirt-characteristics. Shorter sides of the rectangular ring resonator are bent in U-shaped to increase the effective length of the resonator eventually the bandwidth is widened. Filter is designed and simulated for the center frequency of 3.2 GHz, bandwidth from 2.0 GHz to 4.0 GHz, on dielectric constant 3.38 and thickness 0.508 mm. Electromagnetic simulator Ansoft HFSS is used to optimize the filter dimensions.
Highlights
Microstrip wideband bandpass filter is an important RF end component in wireless communication systems
One of the popular design topologies, square ring resonator is used in [3] to design compact ultra-wideband bandpass filter in which two sets of open stubs bent at 900 are running parallelly outside the square ring resonator and one end of open stubs connected to the opposite diagonal corner of the resonator
In [6], UWB bandpass filter is designed with three resonant modes in multimode-resonator based on half-mode substrate integrated structure and four resonant modes are achieved from a pair of electromagnetic band-gap (EBG) incorporated in a pair of parallel coupled lines
Summary
Microstrip wideband bandpass filter is an important RF end component in wireless communication systems. In [6], UWB bandpass filter is designed with three resonant modes in multimode-resonator based on half-mode substrate integrated structure and four resonant modes are achieved from a pair of electromagnetic band-gap (EBG) incorporated in a pair of parallel coupled lines This type of structure is compact in size and produced ultra-large stopband. Compact ultra-wideband bandpass filter is composed of multi-mode resonator (MMR) In this filter three circular shaped patches connected to high impedance open stub are serving as three resonators. Multi-mode resonator in-general is selected in order to design ultra-wide passband compact bandpass filter. This information provides the degree of freedom for the selection of the k values eventually precise value of electrical lengths and centre frequency (fc) can be found
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