Compact Microstrip Lowpass Filter Research Articles

Design of Compact Low Pass Microstrip Filter For Wireless Communication System

A compact microstrip low pass filter has been designed using step impedance technique. Two slots were cut in the ground plane just below the high impedance microstrip lines. The proposed filter has spurious free response for wide band width with sharp cut-off characteristics. The filter has been designed for a cutoff frequency 2.5 GHz and provides good agreement between the simulated and measured results.

Novel Compact Microstrip Lowpass Filters with Wide Stopband Using Defected Ground Structure

In this paper, a novel defected ground structure (DGS) is proposed for lowpass filter (LPF) applications. The proposed structure exhibits wideband attenuation without increasing the circuit size, as compared with the conventional DGS. An equivalent circuit for the proposed DGS is described, and its equivalent-circuit parameters are analyzed and extracted. Benefitting from the quasi-elliptic function of the DGS, a demonstration LPF using one DGS unit and a compensated microstrip line is designed, and an attenuation pole near to the passband edge is realized to enhance roll-off of the stopband. To improve rejection level of the stopband, three cascaded DGS units are utilized for the LPF design. The fabricated LPF shows more than 20 dB attenuation from 2.1 GHz to over 8.0 GHz, as well as sharp rolloff. The simulated and measured results are presented, showing good agreement.

Compact microstrip lowpass filter with very wide stopband using open stubs loaded with defected front coupled tapers

A novel microstrip lowpass filter is proposed to achieve a very wide stopband and high selectivity as well as compact size. This filter utilizes a resonator with symmetric structure that consists of a transmission line, loaded with open stubs. Each stub ends with a defected taper and these tapers are coupled two by two to generate enhanced capacitances and increase the selectivity. Two units of these resonators are then used in combination with open stubs and triangular shaped resonators to widen the stopband and form the final filter. This filter is then fabricated and measured. The measured and simulated results are in good agreement.

Compact microstrip lowpass filter with ultra-wide stopband

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.

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 quasi-elliptic microstrip lowpass filter with wide stopband

A compact microstrip lowpass filter with quasi-elliptic response is proposed. To achieve compact design, both symmetrically loaded radial-shape patches and meandered main transmission line are adopted. To realise the quasi-elliptic response and strengthen the roll-off sharpness for the filter, a coupled capacitor between adjacent radial-shape patches is introduced in interdigital form. Furthermore, the adoption of radial-shape patches and the interdigital structure can introduce both serial and parallel resonance in the circuit. Thus, a wide stopband with 7th harmonic suppression is achieved. A demonstration filter with 3 dB cutoff frequency at 1.18 GHz has been designed, fabricated and measured. Results show that a relative stopband bandwidth of 132.3 (referred to a suppression degree of 15 dB) is obtained while achieving a high figure-of-merit of 11543.

Compact lowpass filter with wide stopband using modified semi-elliptic and semi-circular microstrip patch resonator

A compact microstrip lowpass filter based on a novel patch resonator is reported. The novel semi-circle and semi-ellipse patch resonators are loaded by rhomboid and delta-stub structures, respectively. The filter consists of three cascaded microstrip patch resonators with different dimensions. The stopband with an attenuation level better than -20 dB is obtained from 3.68 up to 19 GHz. The proposed filter has low insertion loss in the passband, sharp, high and wide rejection in the stopband, and compact size. The filter is optimally designed, fabricated and measured. Simulation and measurement results are presented and compared and good agreement with the response of simulation and measurement is demonstrated.

Compact microstrip low‐pass filter using complementary split ring resonators with ultra‐wide stopband and high selectivity

AbstractThe transmission characteristic of the microstrip with complementary split ring resonator (CSRR) is researched. Compared with the conventional structure, this filter can achieve a wider bandgap by shifting the gap of CSRR from the side of the microstrip to the underside. And then, a lower transmission zero can be realized by loading a pair of narrow slots in the gap of the ring. The equivalent circuit model of the structure is provided. By cascading CSRR cells with different transmission zeros, a ultra‐wide bandgap low‐pass filter (LPF), which has a cutoff frequency at 4.3 GHz is designed. The designed LPF has a high performance with an insertion loss lower than 0.3 dB in pass band, a high out‐band suppression more than 20 dB (4.55–25 GHz), and a very sharp transition band about 0.25 GHz (4.3–4.55 GHz). © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 430–433, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24942

Microstrip Coupled-Line Lowpass Filter with Wide Stopband for RF/Wireless Systems

We present the design of a compact microstrip lowpass filter with a wide stopband which is up to ten times the cutoff frequency. The filter is based on a coupled-line configuration and shunt open stubs. The open stubs create additional transmission zeros, which are used to extend the stopband of the filter without any additional components or cascaded units. A prototype lowpass filter with a 3 dB cutoff frequency of 0.428 GHz and a 15 dB stopband extended up to 4.77 GHz is fabricated to validate the theoretical predictions.

Compact microstrip lowpass filter with sharp roll-off and wide stop-band

A microstrip lowpass filter with enhanced performance is developed. The studied filter is based on a novel patch resonator that features strong slow-wave effects, and can also implement either an improved roll-off or an enhanced stop-band. A demonstrator filter with 3 dB cutoff frequency fc =2.4=GHz is optimally designed, fabricated and measured. Results indicate that a roll-off of 92.5=dB/GHz together with a relative stop-band bandwidth of 135.5= (referred to a 30=dB suppression) is obtained while achieving a highest figure-of-merit of 10106. Both simulations and measurements are presented and compared.

Compact quasi-elliptic lowpass filter using symmetric rectangular coupled capacitors

A compact microstrip lowpass filter using symmetric rectangular coupled capacitors is proposed. The introduction of an interdigital structure between the symmetric rectangular capacitors can reduce the filter size, owing to the increase in the loading capacitance, and also can provide the finite attenuation poles, thus quasi-elliptic function and stopband extension are fulfilled. Finally, a demonstration filter is designed, fabricated and tested to show the validity of the proposed lowpass filter structure.

Low Insertion-Loss, Sharp-Rejection and Compact Microstrip Low-Pass Filters

Complementary split ring resonators are used to design compact, low insertion loss (IL), low pass filter with sharp cut-off. A prototype filter implementing area is 0.23 lambdagtimes0.09lambda g, lambdag being the guided wavelength at 3-dB cut-off frequency (fc) 1.887GHz. Maximum IL is within 0.5dB up to 1.717GHz and 20-dB stopband extends up to 3.4fc

Compact Low-Pass Filter with Sharp Skirt Characteristics and Broad Stopband

A new compact microstrip low-pass filter and its equivalent-circuit model are developed. The philosophy of the structure behind this novel microstrip low-pass filter is simple as it is composed of a pair of symmetrical parallel coupled-line and an open-stub. With this configuration, a finite attenuation pole near the stopband cutoff frequency is available and adjustable by simply tuning the circuit parameters. Furthermore, the rejection bandwidth of this type of low-pass filter can be extended. In order to validate the feasibility of the proposed design method, a low-pass filter based on a microstrip structure is designed, fabricated, and measured. Experimental results agree very well with the simulation and analytical results.

Compact microstrip lowpass filter using a meander‐line structure

AbstractA novel compact microstrip lowpass filter using N‐turn meander line structure is proposed. This low pass filter provides a transmission zero near the passband edge and low passband insertion loss. Both the cutoff frequency and transmission zero can be easily controlled by changing the meander line dimensions to ease the filter design. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1339–1341, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21619

Compact microstrip low-pass filter with suppression of spurious response

A novel compact low-pass filter (LPF), with suppression of spurious response, is proposed. The new LPF is compact in size due to the slow-wave effect and proper layout. The LPF, consisting of two shunt-connected LPFs with characteristics of quasi-elliptic function, has a wide stopband with sharp roll-off. A demonstration filter is designed, fabricated and tested. Theoretical and experimental results are presented.

Compact microstrip lowpass filter with wide stop‐band integrating a bandstop structure in an open‐loop resonator

AbstractA novel compact microstrip lowpass filter integrating a bandstop structure in an open‐loop resonator is proposed. The lowpass filter has the advantages of compact size, wide rejection in the stop‐band, and three transmission zeros in the stop‐band for suppressing the harmonics. A demonstration filter is designed, fabricated, and tested. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 582–584, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21236

Compact microstrip low-pass filter with sharp rejection

This letter presents a compact multisection sharp-rejection microstrip low-pass filter. Each section consists of a microstrip line section and an interdigital capacitor. The analysis for optimizing the attenuation poles by adjusting the finger number, and the width and length of the microstrip line section, is presented. The cascaded four-section low-pass filter has a return loss of better than 17 dB and an insertion loss of less than 0.7 dB from DC to 1.6 GHz. The rejection is better than 20 dB from 2.1 to 7.5 GHz.

A novel compact microstrip lowpass filter using a meander open-loop resonator

A novel compact microstrip lowpass filter using a meander open-loop resonator is proposed. The lowpass filter has the advantages of compact size, wide and high rejection in the stopband, and low insertion loss in the passband. A demonstration filter is designed, fabricated, and tested. The theoretical and experimental results are presented. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 66–67, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20725

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

Compact microstrip lowpass filter

A novel compact microstrip lowpass filter using the slow-wave resonator is described. This filter has the advantages of low insertion loss in the passband, high and wide rejection in the stopband and compact size. A demonstration filter is designed, fabricated and tested. Theoretical and experimental results are presented.