Sharp Cutoff Frequency Response Research Articles

Lowpass Filter with Wide Stopband Based on T-Shaped Resonator Loaded Step-Impedance Hairpin Resonator

A lowpass filter with wide stopband based on stepped impedance hairpin resonator is proposed. Multiple transmission zeros are created in the stopband region by different size T-shaped resonator to achieve wide stopband. A lowpass filter with 3dB cutoff frequency (fc) at 3.2GHz is designed, simulated and fabricated. Experimental results indicate that stopband can be extended to more than 7fc with a rejection level of 20dB after loading T-shaped resonator. The insertion loss is lower than 0.4dB and return loss is better than 16dB in the passband. Excluding the feed lines, the size of the filter is less than 0.26λg X 0.06λg. The modified filter is of good value in engineering application for its small size, sharp cutoff frequency response and wide stopband.

Design and Implementation of High Performance Miniature Uniplanar Microwave Low Pass Filter up to 15GHz

Objectives: This work is introduced to design, implementation and specific analysis of printed miniature uniplanar micro strip low pass filter having a cut off of 15GHz on RT/duroid 6010.2 substrate. Methods/Statistical analysis: Besides, the paper examines simulated responses of three circuits which are predominantly lumped element circuit, stepped impedance and EM simulation with respect to conventional design circuit simulations where in both the design strategy will match the tested results. Findings: This proposed work comprises low pass filter design, lumped design and basic design by using only micro strip lines technology. The EM Structure sight design technique gives good sharp cut-off frequency response when compare with other technique towards low insertion loss which brings about having extraordinary concurrence for incredible relationship. Predominantly, AWR microwave office tool is used for designing and analysis. Application/ Improvements: The proposed design configuration will have more extensive application in advancements like 5G, Satellite, radars, Port Vessel Traffic Services and military communication system.

DESIGN AND SIMULATION OF PRINTED MICRO STRIP LOW PASS FILTER BASED ON THE ELECTROMAGNETIC MODELS 18GHZ PRINTED MICROSTRIP LOWPASS FILTER USING X-MODELS

This paper presents the Design, Simulation and characterization of Printed Micro strip Low Pass Filter based on 15 mil Alumina substrate. Simulations show a comparison between a pure EM simulation with EM Sight and a more efficient hybrid approach that combines EM analysis (using X-Models) with conventional circuit simulations and both approaches match the measured data. Furthermore, the proposed paper has four different low pass filter designs, lumped design; basic designs uses only micro strip lines; advanced design uses multiple edge coupled micro strip lines, EM sight design provides a very sharp cut-off frequency response with low insertion loss, results having great agreement with excellent correlation. Tuning and Optimization of the design is carried out using AWR Microwave office tool.

Compact Varactor-Tuned Microstrip High-Pass Filter With a Quasi-Elliptic Function Response

This paper presents a novel circuit topology of a tunable high-pass filter with a quasi-elliptic function response. A detailed theoretical analysis for the performance operating mechanism is demonstrated. With the assistance of mutually inductive coupling introduced, a pair of tunable transmission zeros (TZs) is synthesized at the lower passband edges and significantly improves the filter selectivity. Experiments are carried out by using the liquid crystal polymer bonded multilayer printed circuit board technology to validate the design. It is found that the implemented filter achieves a wide continuous tuning range covering from 1030 to 2150 MHz with low insertion loss, and which indeed are limited by the Schottky diodes used. It is also illustrated that two measured TZs are properly controlled at each tuning stage, which not only offers a sharp cutoff frequency response with a rejection level greater than 22 dB, but also provides an approximately unchanged response shape. Good agreement between the measured and simulated results can finally be observed.

Stamp Modeling, Analysis and Design of Defected Microstrip Structure for Lowpass Filters Based on Properties of Metamaterials

Defected microstrip structure (DMS) is one kind of metamaterials, which has many characteristics that bandgap and slow wave characteristic and so on. Three types of defected microstrip structure (DMS) units which are cross-shaped, round-head-shaped and square-head-shaped DMS are proposed and investigated. Further, three DMS units are used in the design of lowpass filters (LPFs) and the obtained performances are examined. Based on three DMS units, three lowpass filters using sixteen cascaded proposed DMS units are designed and fabricated. The designed LPFs exhibit sharp cutoff frequency response, low insertion loss, and excellent stopband performance.

Compact Continuously Tunable Microstrip Low-Pass Filter

A compact continuously varactor-tuned low-pass filter using microstrip stepped-impedance hairpin resonators is proposed in this paper. A detailed theoretical analysis for the performance tuning mechanism is illustrated by using equivalent circuit models. The experiment results are provided to validate the proposed filter. From the measured results, it is found that five varactor diodes with two applied bias voltages used in the proposed design work well as a flexible tuning network, which not only provide a wide frequency tuning range of 46% from 1.60 to 2.94 GHz, but also offer an ability of selectivity controlling by using different applied voltages. Furthermore, the proposed filter using multiple cascaded hairpin resonators provides a very sharp cutoff frequency response with low insertion loss in each state, together with a wide and deep stopband with a rejection level greater than 20 dB. Good agreement between the measured and simulated results can be observed finally.

A Microstrip Bandpass Filter Based On Novel Resonators

A microstrip bandpass filter (BPF) using a novel defected ground structure (DGS) resonators and inter-digital capacitors is proposed in this paper. The BPF is designed by cascading a novel microstrip highpass filter (HPF) and a lowpass filter (LPF). The LPF with a 3 dB cutoff frequency of 6GHz is constructed by a laddershaped transmission line on the top plane and a combined open loop DGS on the bottom one, resulting high selectivity and good stopband performance. The HPF consists of a ladder-shaped transmission line with zigzag slot on the top plane and the open loop DGS on the bottom one, providing two transmission zeros and steep rejection slope. The designed BPF with a 3 dB bandwidth of 2GHz and center frequency of 5GHz exhibits sharp cutoff frequency response. The BPF also shows good stopband performance with rejection better than 20 dB from DC to 3.55GHz in lower stopband and 6.2 to 14GHz in upper stopband, respectively. The measured results agree well with the simulations.

Compact lowpass filter based on coupled-line hairpin unit

A compact lowpass filter (LPF) with sharp cutoff frequency response and wide rejection bandwidth is proposed. The proposed LPF has a simple structure and comprises one microstrip coupled-line hairpin unit, one spiral slot and two open stubs. A demonstration filter with 3 dB cutoff frequency at 2.0 GHz has been designed and fabricated. Theoretical and simulated results are presented, which are in good agreement with the measured results.

DGS resonator with two transmission zeros and its application to lowpass filter design

A novel defected ground structure (DGS) with two transmission zeros and a sharp cutoff frequency response is proposed. Both the two transmission zeros generated by the new DGS are lower than the one generated by a dumbbell-shaped DGS etched the same square area dimensions. On the basis of the proposed DGS, a lowpass filter has been designed, fabricated and measured. The filter with 3 dB cutoff frequency at 4 GHz exhibits a very sharp cutoff frequency response and an ultra wide stopband with rejection better than 25 dB from 4.2 to 23 GHz. Measured results show good agreement with simulated ones.

Compact lowpass filter with wide stop-band using coupled-line hairpin unit

A novel transmission line configuration is proposed to design a lowpass filter (LPF) with sharp cutoff frequency response and wide rejection bandwidth. The proposed LPF is realised by a cascading microstrip coupled-line hairpin unit, semi-circle defected ground structures and semi-circle stepped-impedance shunt stubs. Theoretical and simulated results are presented, which are in good agreement with measured results.

Compact Elliptic function Lowpass Filter based on Defected Ground Structure

A compact microstrip lowpass filter (LPF) with prominent cutoff sharpness and wide stopband is presented. The microstrip LPF is composed of a broadened microstrip line on the top side of the microstrip structure, an H-shaped defected ground structure (DGS) and a modified dumbbell (DB) DGS in the ground plane. It has a simple design procedure and easily can be tuned. The designed filter is developed and experimental results show that it has a sharp cutoff frequency response.

Compact lowpass filter with sharp transition knee by utilising a quasi--slot resonator and open stubs

Designs of a compact lowpass filter using a slotted-ground-plane resonator are presented. Unlike conventional design of cascading bandstop slotted-ground-plane resonators in the literature, the introduced filter is presented, which consists of a quasi-π slot in the ground plane, and a microstrip line with several stepped-impedance (SI) open stubs. The quasi-π slot provides a very sharp cutoff frequency response with low insertion loss. Furthermore, to increase rejection bandwidth, additional transmission zeros are added into frequency characteristics by connecting the SI open stubs at the microstrip line. An equivalent circuit of the proposed lowpass filter is simply represented by resistor, inductor and capacitor (RLC)-lumped elements. According to measured results, compared with a conventional H-slot resonator, the resonance frequency of the resonator is reduced from 3.5 to 2.0 GHz and the ratio of frequency reduction is about 43%. The measured insertion loss at a passband is below 0.3 dB, and the rejection band over 25 dB is from 1.95 to 9.0 GHz.

Compact size K-band bandpass filter

A novel compact size K-band bandpass filter using triangular closed-loop resonators is proposed. By introducing cross-coupling capacitance between the input and output ports of the filter, a transmission zero in the upper band is obtained. The filter has the advantages of compact size with dimensions of 11×8.6 mm and a sharp cutoff frequency response. It also has good passband characteristics, and the return loss is more than 15 dB. The measured results show good agreement with the simulation results.

Compact Elliptic-Function Low-Pass Filter Using Defected Ground Structure

A novel elliptic-function low-pass filter (LPF) is presented, which consists of a dumb-bell-shaped defected ground structure (DB-DGS), a spiral-shaped defected ground structure (SP-DGS) and a broadened microstrip line. The DB-DGS provides the required wideband attenuation in stopband, while the SP-DGS provides steep transition from passband to stopband. A 2.4 GHz five-pole LPF is developed and experimental results show that it has a sharp cutoff frequency response. The measured passband insertion-loss is below 0.3 dB, and the rejection band over 20 dB is from 2.95 to 8.25 GHz.

New compact microstrip stacked slotted resonators bandpass filter with transmission zeros using high‐permittivity ceramics substrate

AbstractThe miniaturization of hairpin band‐pass filters by employing two high‐permittivity ceramic substrates (with respective dielectric constants of 9.7 and 26.1) are investigated. Microwave dielectric ceramics with high permittivity are commonly applied in several microwave communication components. With the advantages of compact size, high‐permittivity ceramics can be used as the substrate for band‐pass filters. Moreover, the fundamental characteristics of newly developed slotted resonators. In this article, the designed vertically stacked slotted resonators structures are simulated using an IE3D simulator. The responses of the fabricated filters using Al2O3 (εr = 9.7, Q × f = 350,000 GHz) and 0.8(Mg0.95Zn0.05)TiO3‐0.2Ca0.61Nd0.26TiO3 (εr = 26.1, Q × f = 46,000 GHz) ceramic substrates are designed at a center frequency of 2.45 GHz. This vertically stacked slotted resonators and sharp cutoff frequency response band‐pass filter should be useful in many wireless communication systems. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1377–1379, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23366

Design of compact, broad-stopband lowpass filter using modified stepped impedance hairpin resonators

A compact elliptic function lowpass filter using a stepped impedance hairpin resonator is proposed. The filter has the advantages of compact size, low insertion loss, easy fabrication, a wide stopband, and sharp cutoff frequency response. In order to cause a sharp cutoff frequency response and the wide stopband suppression, a coupled stepped impedance resonator is taken into consideration for the newly proposed lowpass filter. A demonstration filter has been designed, fabricated and tested, and the results agree well with the theory. The size of the filter is less than 0.037λg×0.093λg, where λg is the waveguide length at the cutoff frequency 1.5 GHz, and the 10 dB rejection stopband can be extended to more than 15 GHz. The filter is useful for many microwave system applications.

Compact Structure With Three Attenuation Poles for Improving Stopband Characteristics

A novel compact structure with three controllable finite attenuation poles at stopband is presented. The new structure is composed of a pair of symmetrical parallel coupled-lines and a capacitive load. With this configuration, three finite attenuation poles are available, which can improve the stopband characteristics of low-pass filters (LPFs) or the upper stopband performances of band-pass filters. The research method is based on a transmission-line model for tuning the finite attenuation poles. In order to examine the feasibility of the proposed structure, a new type of LPF with broad stopband and sharp cutoff frequency response is designed, fabricated, and measured. The experimental results of the fabricated circuit agree well with the simulation and analytical ones

Microstrip stepped‐impedance hairpin resonator low‐pass filter with defected ground structure

AbstractIn this paper, a new microstrip stepped‐impedance hairpin resonator (SIR) low‐pass filter (LPF) using a defected ground structure (DGS) is proposed. The proposed SIR hairpin low‐pass filter using DGS provides a very sharp cutoff frequency response with low insertion loss. Furthermore, the SIR hairpin low‐pass filter can provide attenuation poles for the wide‐stopband characteristic due to the resonance characteristic of the DGS. Design parameters for the SIR low‐pass filter are derived based on stepped‐impedance theory and the equivalent‐circuit model for the DGS. The experimental results show excellent agreement with the theoretical simulation results. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 405–408, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21364

Compact microstrip stepped-impedance hairpin resonator low-pass filter with aperture

A new microstrip stepped-impedance hairpin resonator (SIR) low-pass filter (LPF) using aperture is proposed. This filter has the advantages of compact size and easy fabrication. Also, it provides a very sharp cutoff-frequency response with low insertion loss of 0.13 dB and wide-stopband characteristic. The filter is useful for many microwave-system applications. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 517–520, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21033

A compact low‐pass filter with ultra‐wide stopband

AbstractThis paper presents a compact microstrip low‐pass filter with ultra‐wide stopband and sharp cutoff frequency response. The conventional shunt open‐stub filter with a slot on the ground plane has a wide stopband at high frequency, and the coupled open‐stub microstrip filter has a sharp cutoff response at low frequency. The combination of these structures gives the filter the characteristics of an ultra‐wide stopband and a prominent cutoff sharpness. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 303–306, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20452