Open Loop Resonator Bandpass Filter Research Articles

Band pass filter comparison of Hairpin line and square open-loop resonator method for digital TV community

The selection of the right filter design method is a very important first step for a radio frequency engineer. This paper presents the comparison of two methods of band pass filter design using hairpin-line and square open-loop resonator. Both methods were applied to obtain filter designs that can work for broadcasting system in digital television community. Band pass filter was simulated using design software and fabricated using epoxy FR-4 substrate. The results of simulation and measurement shown return loss value at 27.3 dB for hairpin line band pass filter and 25.901 for square open-loop resonator band pass filter. Voltage standing wave ratio parameter values were 1.09 and 1.1067 for hairpin line and square open-loop band pass filter respectively. The insertion loss values for the Hairpin line band pass filter and square open-loop band pass filter were 0.9692 and near 0 dB, respectively. Fractional bandwidth, for hairpin line band pass filter, was 6.7% while for square open-loop band pass filter was 4.8%. Regarding the size, the dimension of square open-loop resonator was approximately five times larger than hairpin-line band pass filter. Based on the advantages of the hairpin line method, we recommend that researchers choose the filter for digital TV broadcasting.

Integrated Open Loop Resonator Filter Designed with Notch Patch Antenna for Microwave Applications

This paper presented the design of integrated open loop resonator bandpass filter with notch type antenna for the use in microwave applications. Chebyshev type filter is selected as the filter characteristics and cascaded design with the antenna to produce a single module, Integrated Filter Antenna (IFA). Special feature of the antenna is the implementation of notch on the patch antenna to improve the efficiency. IFA is then simulated in electromagnetic simulation tool, Agilent Advance Design System (ADS) version 2016 and measured using R&S Vector Network Analyzer. It shows that the proposed IFA produced good measured return loss >-30dB with both vertical and horizontal gain of 9.11dBi and 8.01dBi respectively.

Design of Integrated Open Loop Resonator Bandpass Filter Antenna for 2.4GHz Applications

This paper presented the design of integrated filter antenna for 2.4GHz microwave applications. Open loop resonator bandpass filter is designed to increase the bandwidth of the antenna by producing the range of frequencies that can be accepted by the antenna structure. Direct connection between the filter structure and antenna may cause impedance mismatch and deteriorates the performance of both antenna and filter. Thus, by integrating both filter and antenna into a single module, the overall performance can be improved and increase the efficiency of the system with improved bandwidth. The design used FR4 with dielectric constant of εr = 4.7 with substrate thickness of 1.6mm. It is shown that the simulation result for the proposed integrated filter antenna produce return loss, S11=-20.009dB, gain of radiation pattern is 3.36dB and an increase of bandwidth to approximately 3.74% compare to the single structure antenna.

An Improved Microstrip Open-Loop Resonator Bandpass Filter with DGSS for WLAN Application

This paper presents a novel harmonic-suppressed microstrip open-loop resonator bandpass filter with the different transmission line characteristic impedance of the feed line and open-loop resonator for wireless local area network (WLAN) application. To improve the stopband rejection of the filter, the dumbbell-shape defected ground structure (DGS) are applied under the feed lines to suppress the harmonics and the equivalent parameters extraction formulations of double-dumbell-shaped DGSs are the first to proposed. The bandpass filter with center frequency of 2.44 GHz were designed and fabricated on a TLX substrate with thickness of 1 mm and dielectric constant of 2.55. Measurement results show the filter has a wide stopband characteristic with 30 dB attenuation up to 7.5 GHz and only has an –1.23 dB insertion loss while it is a little larger than the conventional one. The measured results are in good agreement with the simulated results. It can be widely used for WLAN application.

RF CIRCUIT DESIGN INTEGRATED WITH MICROSTRIP DGS

This paper presents microstrip transmission lines for designing a microstrip open loop resonator bandpass filter and a novel dual band transmitter. Microstrip open loop resonator bandpass filter with the dumbbell DGS under feed lines enhances the harmonic suppressed at the center frequency of 2.44 GHz. An asymmetric dumbbell DGS-integrated microstrip line is applied to the dual band transmitter which performs as a frequency doubler at 6.8 GHz or a power amplifier at 2.4 GHz. For the proposed bandpass filter, it has a wide stopband characteristic with attenuation −25 dB up to 8 GHz and has an −1.25 dB insertion loss by using two dumbbell DGS. Measurements of the dual band transmitter show that in frequency double mode, fundamental suppression and maximum output are −41 dBc and 7.8 dBm. And in amplifier mode, second harmonic suppression, P1 dB and gain achieve −52.6 dBc, 13.7 dBm and 16.5 dB, respectively.

Microstrip Open Loop Resonator Bandpass Filter with DGS for WLAN Application

This paper presents a novel harmonic-suppressed microstrip open loop resonator bandpass filter with defected ground structure (DGS) for wireless local area network (WLAN) application. To improve the stopband rejection of the filter, DGSs are applied under the feed lines to suppress the harmonics. The bandpass filter with center frequency of 2.44 GHz is designed and fabricated on a TLX substrate with thickness of 1 mm and dielectric constant of 2.55. By using two dumbbell-shape DGSs the filter has a wide stopband characteristic with attenuation −25 dB up to 8 GHz and has an −1.25 dB insertion loss while it demonstrates a little larger than the conventional one. The measured results agree well with the simulation results. The proposed filter is found to possess low in-band insertion loss and high out-band suppression, making it suitable in WLAN application.

Compact hexagonal open-loop resonator bandpass filters using capacitive side-coupled stub and spurline technique

Compact quasi-elliptic bandpass filters using hexagonal open-loop resonators are presented. To miniaturise circuit size, a pair of capacitive side-coupled stubs and two pairs of spurlines are placed skilfully into the filter structure. The new filter operating at 1.65 GHz was analysed, simulated and fabricated. Good agreement between simulations and measurements verified the validity of the methodology. Moreover, the circuit size only occupies 21.1×14.1 mm2 (≃0.21λg×0.14λg).

COMPACT AND HARMONIC SUPPRESSION OPEN-LOOP RESONATOR BANDPASS FILTER WITH TRI-SECTION SIR

Abstract—A compact open-loop resonator bandpass filter with suppression of the second and the third harmonics is demonstrated in this paper. This novel filter is based on a Tri-Section SIR to achieve size minimization and suppressed spurious response. The simulations and measurements of a 0.9 GHz prototype bandpass filter are presented. The measured results agree well with simulation and calculation.

A Compact C-CMRC Feeding Open-Loop Resonator for Harmonic Rejection Bandpass Filter

A compact open-loop resonator bandpass filter is presented to suppress the spurious passband using compensated compact microstrip resonant cell (C-CMRC) feeding structure. Based on the inherently compact and stopband characteristics of the C-CMRC feeding, the proposed filters shows a better spurious rejection performance than the only open-loop resonator filter. The suppression is -57.4 dB, -49.5 dB, and -43.9 dB at the 2nd, 3rd and 4th harmonic signal separately. All the performance of proposed filters have been verified by the measured results.