A compact microstrip lowpass filter with sharp selectivity and wide stopband designed on the basis of dual-plane, is presented. Initially, a basic one pole defected ground structure (DGS) filter is modified so as to achieve sharp selectivity as well as compact size. The modified DGS reduces the circuit size of the filter by 68.8%. To suppress the higher order harmonics, mirrored symmetrical uniform impedance stubs are designed in the top surface of the substrate, thereby wide stopband up to 20 GHz is achieved. The stopband suppression level of the filter is improved by incorporating a spurline resonator which acts as a defected microstrip structure (DMS) in the top microstrip line. The designed filter has 3 dB cutoff frequency of 2.11 GHz with high relative stopband bandwidth of 159.2% within the rejection level of 18 dB. The wide passband frequency range of the proposed filter covers the GSM, GPS, Wi-Fi communications and various L-band applications such as aircraft surveillance etc.

Compact microstrip lowpass filter with high harmonics suppression using defected structures

A Compact Dual Band-Bandpass Filter (DB-BPF) with wide stopband rejection is proposed in this article The basic tools used in the structure are Short Circuited Stepped Impedance Resonators (SCSIR), Open Stub Resonators (OSR) First, a Single Band-Bandpass Filter (SB-BPF) is designed with wide stopband rejection, and then it is modified to DB-BPF Both the SB-BPF and DB-BPFs have similar type of construction except for an additional SCSIRs used in DB filter The structure of the filters, use the source-load coupling and OSR to generate transmission zeros, which suppresses harmonics and achieves wide stopband The use of SCSIRs make the SB and DB bandpass filters size compact to 0099λg×0094λg and 0118λg×0092λg, where λg is guided wavelength with a wide stopband upto 685f0 with 22 dB suppression for SB-BPF and 278f1/757f0 with 22 dB suppression for DB-BPF, where f0 and f1 are centre frequencies of first and second passbands respectively

Compact dual bandpass filter for terrestrial radio and GSM applications

A novel microstrip tunable dual-band bandpass filter with high attenuation level in the upper stopband region is presented. The proposed structure comprises of T-shaped resonators and the coupled microstrip feeding lines. To reach a compact size, the feeding lines are bended. By altering the physical lengths, the characteristics of BPF can easily tune. So, the operational frequencies of the filter can be adjusted and has been fixed to 2.1 GHz and 2.63 GHz, which are applicative for 3G and 4G systems. The insertion-losses of the first and second pass-bands are only 0.68 dB and 1.08 dB, respectively. The undesired harmonics in the upper stopband, with an excellent attenuation level of −38 dB, are rejected up to 6.65 GHz. The results exhibit high return loss of 19.3 dB and 30.7 dB in the first and second pass-bands. The proposed circuit has been fabricated and tested that the obtained results are well close to the simulations results. The total size of the designed circuit is only 16.4 × 13.4 mm 2 .

Design of a compact microstrip tunable dual-band bandpass filter

In this paper, two compact tuneable bandpass filters (BPFs) based on the coupled feed lines are introduced. To approach a compact size, the coupled feed lines are bended. To design a high performance single-band bandpass filter (BPF), coupled feed lines are loaded by T-shaped stubs (as main resonators) and rectangular stubs (as suppressor stubs). Also, the mechanism of coupled feed lines combining with T-shaped open stubs is analyzed to show a tunable passband. The dual-band BPF includes two big radial-stubs, two small radial-stubs, two T-shaped structures and spiral coupled feed lines. The LC model of big radial-stubs is analyzed to compute the equation of transmission zero using its transfer function. The passband frequency of single-band BPF resonates at 2.12 GHz (3G) with corresponded insertion loss of 0.83 dB. Also, for dual-band BPF, the measured insertion-losses of first and second passbands are close to 0.8 and 1.1 dB, respectively. The frequency responses of BPFs are easily adjusted by altering the physical dimensions, demonstrating a adjustable performance. To verify the correct operation of circuits, the proffered filters are implemented and tested.

Microstrip bandpass filters using coupled feed lines for third and fourth generation communications

This paper, for the first time, presents a design technique to realize a miniaturized dual-band bandpass filter based on E-shape microstrip structure for integrated wireless multi-band communication systems. The filter is patterned on a double layer substrate to achieve compact size. On the bottom layer, two E-shape microstrip structures are realized and coupled through a space gap g c to perform the specified dual passbands. The filtering response of the two passbands is improved using a top layer substrate employs two λ /4 short-circuited stubs coupled through one via hole. These two filter circuits are capacitively coupled using overlapping microstrip lines. To demonstrate the technique and design process, a multi-band bandpass filter is developed to serve a multi-communication system having center frequencies of 2.4/5.3 GHz. The filter is designed, simulated and measured. The results from the simulation and measurement show good agreement. The filter circuit size is very small about 4.24 mm × 6.76 mm × 0.63 mm excluding the feeding ports.

Miniaturized dual-band bandpass filter using E-shape microstrip structure

Recently the E-shape microstrip structure was proposed in order to develop miniaturized ultra-wide band (UWB) bandpass filters. In spite of its attractive features, no thorough analysis of this structure is available in the literature. In this paper, the E-shape microstrip structure with grounded center conductor is analyzed and, for the first time, an approximate equivalent circuit is proposed for its behavior. Based on the equivalent circuit, two compact second-order microwave filters with UWB responses are designed, fabricated and measured. The approximate dimensions of the filter covering the whole UWB is about 3 mm × 1.5 mm × 0.4 mm. The theoretical and measured responses of the filters show good agreements.

http://ieeexplore.ieee.org/iel5/6088932/6101646/06101791.pdf

A lumped element equivalent circuit of E-shape microstrip structure for UWB filter design

Summary form only given, as follows. One type of E-shape microstrip structure is composed of half wave length hairpin resonator loaded by a grounded stub at its middle. For the first time, using an equivalent circuit for this structure, high-order UWB bandpass filter design technique is presented based on cascading E-shape microstrip structures. Two third-order UWB bandpass filter are designed, simulated, fabricated and measured. These filters have compact sizes approximately smaller than 3.5mm × 3.2mm × 0. 4mm. The theoretical and measured results show excellent agreement. It is observed that UWB bandpass filters with the E-shape microstrip structure are capable of offering campact circuit size, flat group delay, good selectivity, excellent wideband rejection and low insertion loss.

High-order UWB bandpass filter using cascading e-shape microstrip structure

In this article, a compact bandstop filter (BSF) with desirable four attenuation narrow bands is developed for multiple wireless network systems. The developed filter composes of two microstrip circuits. In the first microstrip circuit, stepped-impedance and two open-circuit stubs in defected microstrip structure (DMS) are analyzed to generate the first and the second rejection bands. The third and the fourth stopbands are realized using a second microstrip circuit consist of two dual-mode resonators. This circuit are capacitively coupled to the DMS-circuit. The filter attitude is very well explained using a coupling mechanism diagram. To demonstrate the developed concept, dual and quad-bandstop filters are designed, fabricated, and measured to supress the frequencies of (2.4 GHz and 5 GHz WLAN) and (1.56 GHz GPS, 2.4 GHz WLAN, 3.5 GHz WiMax, and 5.25 GHz WLAN) respectively. The measured results agree with the predicted ones closely. The measured responses improved that the quad-BSF can apply 10 dB attenuation bandwidths of 81 MHz, 73 MHz, 60 MHz, and 129 MHz centred at 1.56 GHz, 2.4 GHz, 3.5 GHz, and 5.25 GHz respectively. The designed filter has overall circuit area of 125 mm2 excluding the feeding ports.

Compact multiple bandstop filter using integrated circuit of defected microstrip structure (DMS) and dual-mode resonator

In order to prevent interference with some selected narrowband communication channels, UWB filters with rejections at these bands are preferred or sometimes necessary for some UWB systems. In this paper, for the first time, a technique for generating rejection notches in the miniaturized UWB filters employing the E-shape microstrip structure is presented. It is shown the attenuated bands can be achieved by capacitively coupling grounded quarter wavelength (λ g /4) stub or E-shape microstrip structures to the main filter structure. The performances of a second-order filter with a single rejection notch and a third-order filter with one and two rejection notches are evaluated using an accurate equivalent circuit model as well as by simulation and measurement. The dimensions of the third-order filter are about 4 mm × 4.2 mm × 0.4 mm excluding the feeding ports.

http://ieeexplore.ieee.org/iel7/6476772/6483692/06483921.pdf

Raaed T. Hammed

Papers

Miniaturized dual-band bandpass filter using E-shape microstrip structure

A lumped element equivalent circuit of E-shape microstrip structure for UWB filter design

High-order UWB bandpass filter using cascading e-shape microstrip structure

Compact multiple bandstop filter using integrated circuit of defected microstrip structure (DMS) and dual-mode resonator

Compact multi-notched UWB bandpass filter using E-shape microstrip structure