CPW Filters with Defected Ground Structures for RF and Microwave Applications

Both radiofrequency (RF) and microwave (MW) ablation devices are clinically used for tumor ablation. Several studies report less dependence on vascular mediated cooling of MW compared to RF ablation. We created computer models of a cooled RF needle electrode, and a dipole MW antenna to determine differences in tissue heat transfer.We created Finite Element computer models of a RF electrode (Cooled needle, 17 gauge), and a MW antenna (Dipole, 13 gauge). We simulated RF ablation for 12 min with power controlled to keep maximum tissue temperature at 100 ºC, and MW ablation for 6 min with 75 W of power applied. For both models we considered change in electric and thermal tissue properties as well as perfusion depending on tissue temperature. We determined tissue temperature profile at the end of the ablation procedure and calculated effect of perfusion on both RF and MW ablation.Maximum tissue temperature was 100 ºC for RF ablation, and 177 ºC for MW ablation. Lesion shape was ellipsoid for RF, and tear-drop shaped for MW ablation. MW ablation is less affected by tissue perfusion mainly due to the shorter ablation time and higher tissue temperature, but not due to MW providing deeper heating than RF. Both MW and RF applicators only produce significant direct heating within mm of the applicator, with most of the ablation zone created by thermal conduction.Both RF and MW applicators only directly heat tissue in close proximity of the applicators. MW ablation allows for higher tissue temperatures than RF since MW propagation is not limited by tissue desiccation and charring. Higher temperatures coupled with lower treatment times result in reduced effects of perfusion on MW ablation.

In this paper, we design and implement a coplanar waveguide (CPW) bandpass filter utilizing defected ground structure (DGS) technology. The CPW DGS technology, which only needs one or a series connection of a few cells to exhibit the bandgap characteristics, can provide the attenuation poles in the upper and lower bands to improve the rolloff characteristics of the bandpass filter. Moreover, the equivalent lump values of the CPW DGS are also calculated and good agreement between EM simulation and numerical calculation is obtained. The measured results show that the improved selectivity of upper and lower bands are 10.7 and 46.5 dB/GHz, respectively. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 331–334, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20294

This paper addresses DGS based inductively coupled bandpass filters fabricated on Coplanar Waveguide (CPW) technology. The addition of the DGS to the conventional inductively coupled resonator BPF allows the miniaturization of the resonator by exploiting the transversal dimensions of the CPW, while maintaining its performance with respect to insertion and return loss values. On the other hand, the DGS cell allows reconfiguration of the structure from a single band to a multiband BPF. The design procedure of the filters with the DGS is explained with filters designed at 5 GHz. Simulated and measured results show good agreement.

A multi-band band stops filtering (MB-BSF) characteristics with modified dual-polarized dipole antenna using the grounded coplanar waveguide (GCPW) filter for the 3G, 4G, and 5G base station applications are explored in this research paper. Firstly, the modified dipole arms are arranged in a crisscross manner to generate orthogonal polarizations with CPW feed designed to operate in the frequency band of 1.6-3.6 GHz. Secondly, meandered slot GCPW is patterned on the modified dipole antenna and is modeled to provide band stop characteristics with sharp roll-off for 3G, 4G, and 5G. As an outcome, the anticipated antenna is operating in the band of 1.6–2.78 GHz and 3.2–3.8 GHz for VSWR < 1.6 with a guard band of 2.85–3.18 GHz. The proposed antenna provides the isolation of more than 30 dB, the half-power beam width of 70 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> ±1 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> , and realized gain of 8.73 dBi throughout the operating band of 3G, 4G, and 5G for Base Transceiver Station (BTS) applications.

Several coplanar waveguide series stubs and filter structures based on such stubs were designed and manufactured on standard semiinsulating GaAs substrates and thin GaAs membranes as well as on silicon based thin dielectric membranes. Coplanar waveguide circuits realized on thin membranes offer significant advantages over conventional coplanar or microstrip lines for monolithic or hybrid MIC applications.

This paper explores the potential of phase change materials (PCM) for dynamically tuning the frequency response of a dumbbell u-slot defected ground structure (DGS)-based band stop filter. The DGSs are designed using co-planar waveguide (CPW) line structure on top of a barium strontium titanate (Ba0.6Sr0.4TiO3) (BST) thin film. BST film is used as the high-dielectric material for the planar DGS. Lower insertion loss of less than -2 dB below the lower cutoff frequency, and enhanced band-rejection with notch depth of -39.64 dB at 27.75 GHz is achieved by cascading two-unit cells, compared to -12.26 dB rejection with a single-unit cell using BST thin film only. Further tunability is achieved by using a germanium telluride (GeTe) PCM layer. The electrical properties of PCM can be reversibly altered by transitioning between amorphous and crystalline phases. We demonstrate that incorporating a PCM layer into a DGS device allows for significant tuning of the resonance frequency: a shift in resonance frequency from 30.75 GHz to 33 GHz with a frequency shift of 2.25 GHz is achieved, i.e., 7.32% tuning is shown with a single DGS cell. Furthermore, by cascading two DGS cells with PCM, an even wider tuning range is achievable: a shift in resonance frequency from 27 GHz to 30.25 GHz with a frequency shift of 3.25 GHz is achieved, i.e., 12.04% tuning is shown by cascading two DGS cells. The results are validated through simulations and measurements, showcasing excellent agreement.

In this paper, a microfluidically reconfigurable coplanar waveguide (CPW) filter is presented with a tuning range of $\sim$ 1.6:1 and four different states. The passband frequency of the filter is changed based on employing the capacitive loading effect of a liquid metal placed on top of each CPW resonator using three parallel micro-channels. In addition, because of the loading effect of the metal bridges, miniaturization by a factor of 40% is achieved. The filter is digitally tuned from 3.4 to 5.5 GHz with an insertion loss of less than 5.0 dB and a relative bandwidth of 5 $\pm$ 0.35%. The RF power-handling capability of the filter is characterized using a customized measurement setup. It is observed that the filter can be used for input RF powers of up to $\sim$ 20 W for short-duration excitation conditions and 10 W for high-average-power excitation conditions. The filter is realized using common printed circuit board technology and a polydimethylsiloxane structure. Design methodology, simulation, and measurement results of the filter prototype are presented.

This paper introduces the design of low pass filter for radar applications. The main block of the proposed filter is the combination of defected microstrip structure (DMS), compensated microstrip capacitors, and two defected ground structures (DGS). The proposed filter has several desirable features such as low insertion loss of 0.3 dB within the pass band, a wide rejection band from 1.5 GHz to 8.3 GHz with more than 20 dB attenuation, as well as sharp cutoff. Moreover, the proposed design has a compact size of 5.8cm×3.5cm. Experimental measurements of the fabricated filter agree with simulation results, which confirm that the proposed DMS/DGS filter design is suitable for radar and microwave applications.

Design of multipurpose digital FIR double-band filter using hybrid firefly differential evolution algorithm

In this paper, an analytical method of resonant frequency, tuning range, the effective relative dielectric constant, and characteristic impedance is proposed, which is for coplanar waveguide (CPW) resonator loaded by defected ground structure (DGS) and micro-electromechanical systems (MEMS) capacitors. The analytical solution is achieved by an employing equivalent method. The resonant frequency, tuning range, and effective relative dielectric constant are obtained by the analytical solution. For verifying the effectiveness of the proposed method, a CPW tunable bandstop filter (BSF) with DGS and MEMS capacitors is designed, simulated, and fabricated, results show good effectiveness of the proposed analysis method. By changing the height of the MEMS beam with the actuation voltage, the designed BSF can switch the center frequency among three states (i.e. 18.5 GHz, 18.2 GHz, 17.5 GHz, respectively), and fractional bandwidth is changed as well (i.e. 37.8%, 45.6%, 49.5%, respectively).

A novel 1.8 GHz compact microstrip low pass Filter (LPF) based on quasi‐Yagi defected ground structure (DGS) and compensated capacitors is proposed in this article. The filter has a very sharp cut‐off frequency response with low insertion loss and achieves a wide reject band with overall 20 dB attenuation from 2.8 GHz up to 10 GHz. The equivalent circuit model of Yagi‐DGS unit is derived using AWR software and the circuit parameters are extracted by using a simple circuit analysis method. The advantage of this structure is that the reject band can be controlled by tuning the dimension of yagi‐arms at higher frequency rang. To improve the filter characteristics in reject band, a new metal box has been used to minimize the loss in pass band and to extend the reject band. The proposed LPFs are designed and fabricated. The compact filter occupies an area of (0.45 λg × 0.35 λg) with λg = 44 mm. A comparison between simulation and measurement results confirms the validity of the LPF configuration and design procedure. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:523–528, 2014

A switched filter bank with 2N states for an N channel system is designed, fabricated, and tested. The design implements input and output manifold-coupled multiplexers with tunable filters. The bandwidth associated with a channel filter can be added or removed by actuating switches placed within the filter itself. This type of tuning allows for the switching of channel filters without affecting the other filters connected to the manifold. The concept is demonstrated using coplanar waveguide filters and diplexers.

Improved performances, compact size, and lower cost are the key driving factors for advancement of modern communication systems. To meet these stringent requirements, defected ground structures (DGS) can be an effective tool. In this article, a comprehensive review of various DGS configurations emphasizing the background and evolution, classification, equivalent circuit modeling techniques, and their applications in different areas of microwave engineering has been presented. A review of different DGS‐engineered band stop filters (BSFs), low‐pass filters (LPFs), and high‐performance band‐pass filters (BPFs) is included. An overview of the applications of DGS in performance improvements of microwave antennas in terms of impedance matching, size reduction, spurious response suppression, mutual coupling reduction, cross‐polarized radiation suppression, and application of DGS in accomplishing a beam‐steering operation for a phased array antenna has also been included. Radio frequency identification (RFID) and microwave sensors, which are finding increased application, are introduced, and applications of DGS in conventional and chipless RFID tag design as well as in low‐cost passive microwave sensor implementation are also discussed. Additionally, applications of DGS in high‐impedance microstrip line realization and in output power and operational efficiency enhancement of microwave active circuits like oscillators and power amplifiers are covered. Finally, some limitations and challenges of DGS implementation in microwave circuits and antennas are discussed. Overall, adaptation of DGS in conventional passive and active microwave applications and in new emerging fields, like RFID and sensors, are covered in this article.

Coplanar waveguide (CPW) transmission lines periodically coupled to split‐ring resonators (SRRs) are analyzed, designed, and characterized. Due to inductive coupling between the lines and SRRs, signal propagation is inhibited in the vicinity of the resonant frequency of the rings. The result is a stop‐band behavior that can be of interest for the elimination of frequency parasitics in CPW‐based devices. Two different approaches are envisaged: a uniplanar structure, where CPW and rings share the same metal level; and a bimetal structure with SRRs etched on the back side of the substrate. It has been found that the latter exhibits almost negligible insertion losses in the pass band, and sharp cutoff and a high level of rejection in the stop band, with few unit cells. Since ring dimensions are small compared to the signal wavelength at resonance, the proposed SRR‐CPWs are very promising for the design of miniaturized microwave circuits. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 3–6, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11269

A Dual polarized antenna with guard band characteristics with modified dual-polarized dipole antenna using the grounded coplanar waveguide (GCPW) filter for the 3G, 4G, and 5G base station applications are explored in this research paper. Firstly, the modified dipole arms are arranged in a crisscross manner to generate orthogonal polarizations with CPW feed designed to operate in the frequency band of 1.6-3.6 GHz. Secondly, meandered slot GCPW is patterned on the modified dipole antenna and is modeled to provide band stop characteristics with sharp roll-off for 3G, 4G, and 5G. As an outcome, the anticipated antenna is operating in the band of 1.6-2.78 GHz and 3.2-3.8 GHz for VSWR < 1.6 with a guard band of 2.85-3.18 GHz. The proposed antenna provides the isolation of more than 30 dB, the half-power beam width of 70o±1 0, and realized gain of 8.73 dBi throughout the operating band of 3G, 4G, and 5G for Base Transceiver Station (BTS) applications. Simulation studies shows that for the deployed cell sites, the maximum downlink data rate and throughput were 2.03 Mbps and 50.97 Mbps, and the maximum uplink data rate and throughput were 0.15 Mbps and 35 Mbps. The maximum received power and SNIR are -50 dBm and 60 dB, and the maximum RSRP of -65 dBm, RSRQ of -11 dB, and RSSI of -40 dBm.