Four decade bandwidth uniplanar balun

A new realisation of a double junction balun with four decade bandwidth is presented. The balun is designed using coplanar line (CPS) and coplanar waveguide with finite ground planes (CPW/sub FGP/). The simple theoretical model which describes the double junction balun as the all-pass network has been introduced. The measured VSWR is less than 1.3 and insertion loss less than 0.5 dB in the frequency range 300 kHz-4.0 GHz.<>     

A 0–55-GHz Coplanar Waveguide to Coplanar Strip Transition

A broadband coplanar waveguide (CPW) to coplanar strip (CPS) transmission line transition directly integrated with an RF microelectromechanical systems reconfigurable multiband antenna is presented in this paper. This transition design exhibits very good performance up to 55 GHz, and uses a minimum number of dissimilar transmission line sections and wire bonds, achieving a low-loss and low-cost balancing solution to feed planar antenna designs. The transition design methodology that was followed is described and measurement results are presented.     

CPW Circulators with Barium Ferrite Thin Films

A miniaturized circulator using barium ferrite films with a coplanar waveguide(CPW) structure is designed and optimized by high frequency electromagnetic field simulations based on finite element methods.The best circulation performance of the film circulator based on 10 μm thick barium ferrite thin films is obtained with an insertion loss of 0.13 dB and an isolation of 22.89 dB around 36.9 GHz.The microwave characteristics of film circulators with CPW and CPW with ground(CPWG) structures have been compared.The influences of the gap between the ground and the signal line,and the ferromagnetic resonance line width on the microwave properties are also studied.     

Low-loss micromachined inverted overlay CPW lines with wideimpedance ranges and inherent airbridge connection capability

A new type of overlay coplanar waveguide (CPW) structure, “inverted overlay CPW (IOCPW)” is developed using micromachining techniques to provide easy means of airbridge connection between the ground planes, as well as to achieve low losses over wide impedance ranges. Measured IOCPW showed less than 1 dB/cm loss at 50 GHz over a wide impedance range from 25 to 80 Ω. It also offered low effective dielectric constant, and insensitivity to the substrate losses. Wide impedance ranges and simple process steps make IOCPW a promising uniplanar transmission line medium for mm-wave monolithic applications     

A Fully Embedded 60-GHz Novel BPF for LTCC System-in-Package Applications

In this paper, a novel LTCC stripline (SL) 60-GHz band-pass filter (BPF) composed of transitions to coplanar waveguide (CPW) pads for monolithic microwave integrated circuit integration is presented. For low-loss interconnection with active devices, a CPW-to-SL vertical via transition integrating air cavities and a CPW-to-CPW planar transition using internal ground planes are proposed and implemented. The fabricated transition shows an insertion loss of 1.6 dB and a reflection loss below -20 dB at the passband of the filter. The implemented SL BPF using dual-mode patch resonators shows a center frequency of 60.4 GHz, 3.5 % bandwidth, and reflection losses below -15 dB at the passband. Excluding the insertion loss of the transitions, the filter insertion loss reveals 4.0 dB     

新型宽带GCPW射频传输转换

本文提出了一种新型宽带GCPW(Grounded Coplanar Waveguide,地面共面波导)射频传输转换结构,用于解决两个不同平面背靠背式的GCPW射频传输转换。首先将GCPW转换为CPW,宽带共面波导的传输转换是通过金带连接的方式实现传输平面的转换。在工作频率为2GHz—17.5GHz,带宽为15.5GHz的条件下,这种传输转换形式实现了传输损耗小于0.5d B,回波损耗大于16.7d B。这种传输方式较好的解决了较大间距背靠背式GCPW射频信号的传输转换,而且过渡结构简单,尺寸小,工程上容易实现。     

Miniaturized wideband dual linearly and circularly polarized printed square slot antenna for multiradio wireless systems

A dual symmetrical coplanar waveguide (CPW)-fed small size wideband printed square slot antenna (SSA) with dual linearly and circularly polarized radiation capability is presented. The antenna is composed using a square slot, two symmetrical orthogonal CPW feed lines connected to horizontal and vertical arm of L-shaped radiator, an embedded parasitic inverted-L strip at the lower left corner of the square ground slot and engraving slots in the ground plane. Circular polarization (CP) is achieved due to two orthogonal CPW feed lines and a common L-shaped radiator. Isolation between ports is improved by engraving slots at the lower left corner of ground plane and embedded parasitic inverted-L strip. The sense of dual-polarization can be changed in pass-band by changing the port excitation. Measured antenna reveals that an 84.4% (4.6 GHz, 3.15–7.75 GHz) −10 dB impedance bandwidth (IBW) and about 33% (2.03 GHz, 5.12–7.15 GHz) 3-dB axial ratio bandwidth (ARBW). Isolation between ports <−16 dB is achieved over usable CP band.     

Wide-band microstrip-to-coplanar stripline/slotline transitions

Wide-band microstrip line to coplanar stripline (CPS) transitions are proposed. The transition consists of a multisection matching transformer and a quarter-wavelength radial stub for the impedance matching and field matching between the microstrip line and CPS, respectively. The proposed planar transition has the advantages of compact size, wide bandwidth, and straightforward design procedure. Several parameters are studied through simulations and experiments to derive some design guidelines. With the return loss of better than 14 dB, the 1- and 3-dB back-to-back insertion loss bandwidth can cover from 1.4 to 6.6 GHz (1 : 4.7) and from 1.1 to 10.5 GHz (1 : 9.6), respectively. In addition, the microstrip-to-CPS transition is extended to design a microstrip-to-slotline transition by tapering the CPS into a slotline. From 2.7 to 10.4 GHz (1 : 3.85), the back-to-back return loss is better than 15 dB and the insertion loss is less than 3 dB.     

A wideband coplanar stripline to microstrip transition

A wideband coplanar stripline (CPS)-to-microstrip line was developed. The transition has a simple structure for the ease of fabrication with low cost. The measured performance of two back-to-back transitions exhibits an insertion loss of less than 3 dB and a return loss of better than 10 dB over a bandwidth from 1.3 GHz to 13.3 GHz (1:10.2). For narrower bandwidth, an insertion loss of less than 1 dB with a return loss of better than 10 dB was achieved from 1.4 GHz to 7.3 GHz (1:5.2)     

一种新型叉指式共面波导的设计与制作

设计制作了一种新型叉指式共面波导传输线并对其性能进行了初步的研究。通过微加工技术加厚的接地线可以减少传输线平行部分之间的相互干扰,仿真和测试表明在5~20GHz范围内其回波损耗有两个极小值,极小值的位置随传输线结构参数的变化而变化。以-20dB为基准,这两个极小值附近的带宽可以达到1.95GHz,相对带宽分别可以达到23.5%和9.97%,相应的插入损耗在0.33dB/cm和0.5dB/cm左右。这种传输线有助于减小器件整体尺寸,在带通滤波器和移相器的设计方面有重要用途。     

Compact CPW-Fed ultrawideband MIMO antenna using hexagonal ring monopole antenna elements

In this paper, a compact coplanar waveguide (CPW) fed ultra-wide band (UWB) multi input multi output (MIMO) antenna is proposed. The antenna consists of two antiparallel hexagonal ring monopole elements. Circular arcs shaped grounded stubs are used to enhance the isolation, both the arcs are connected through stub to make common ground. Tapering of the slots of CPW feed line at feed point, and grounded slots are introduced for impedance matching over UWB. The proposed antenna is fabricated and impedance bandwidth, isolation, radiation pattern, and gain are measured. Moreover, envelop correlation coefficient (ECC) results are given. Proposed antenna structure operates in the frequency range 3–12 GHz with a fractional bandwidth of 120% keeping isolation better than 15 dB. The antenna has a compact size of 45 × 25 mm².     

A compact planar ultra-wideband bandpass filter with multiple resonant and defected ground structure

A compact bandpass filter with dumbbell shape Defected Ground Structure (DGS) operating on ultra wide pass band (UWB – 3.1 to 10.6 GHz) is proposed. It is based on hybrid microstrip coplanar waveguide (dual sided metal) structure. A Multiple Resonant Structure (MRS) is constructed using coplanar waveguide (CPW) planar transmission line. The MRS makes the resonance using quarter wavelength and half wavelength open-ended CPW. The equispaced three resonances at lower (3.1 GHz), center (6.85 GHz) and higher edge (10.6 GHz) of the whole Ultra Wide Band is achieved using CPW MRS. To make the band as flat as possible, two more resonances are introduced using quarter wavelength microstrip patches on top of the commonly shared substrate, so the proposed filter becomes a five pole bandpass filter. A dumbbell shaped defected ground structure on either side of CPW MRS improves the return loss almost less than 20 dB over the whole UWB passband. The simulated results of proposed filter show good transmission response within passband and good rejection in out of the band. The simulated and measured results are very close to each other which proves the efficacy of proposed design.     

Via-free broadband microstrip to CPW transition

A broadband microstrip to coplanar waveguide (CPW) transition is proposed. The design is based on vertical resonant coupling between the microstrip and CPW. The transition does not require via holes, wire bonds, or air bridges. The design of the transitions at C band shows good agreement with return loss better than -15 dB over 2.8-7.5 GHz. The new transition has the advantages of broad bandwidth and easy fabrication     

High frequency electrical circuits on a planar lightwave circuitplatform

We investigated the propagation losses and the characteristic impedances Z_L of coplanar waveguides (CPWs) and microstrip lines (MSLs) on a planar lightwave circuit (PLC)-platform formed on a silica/silicon substrate. The loss of the CPWs was 2.7 dB/cm at 10 GHz on the PLC-platform with 30 μm thick silica layer. Thus, a cm-order circuit of this CPW is difficult to fabricate in the 10 Gb/s module. This is because the silicon substrate has a large loss tangent (tan δ). On the other hand, the loss of the MSLs, where a ground plane shielded the high loss silicon substrate, could be improved to 0.9 dB/cm at 10 GHz with 30 μm thick polyimide. These lower loss MSLs on a PLC-platform can be applied to module operation at 10 Gb/s. Furthermore they have the advantage that they are suitable for application to array device circuits or circuits in a module where several devices are integrated because unlike CPWs the ground planes are not divided by signal lines or DC bias lines. The structure of CPWs and MSLs on a PLC-platform with a Z_L of 50 Ω was also studied in detail     

Design and fabrication of a new micromachined interdigital coplanar waveguide

In this paper, a new micromachined interdigital coplanar waveguide (CPW) structure has been developed and its characteristics have been studied as a function of transmission line parameters. In interdigital CPW, the ground conductor is thickened by micromachining techniques which is helpful for reducing the interference between the adjacent center conductors while microwave transmits along it. Within the frequency range from 5 to 20 GHz, the return loss of this structure has two minimal values whose positions change with the structural parameters. The relative bandwidths reached 23.5% and 9.97% at 8.3 and 16.55 GHz while the insertion losses are about 0.33 and 0.5 dB/cm, respectively. The interdigital CPW is useful for designing bandpass filter and phase shifter and minimizing the whole size of microelectromechanical system (MEMS) devices.     

Ku-band RF MEMS tunable comb line band reject filter on coplanar transmission line

A band reject filter with tuning capability is presented on a CPW transmission line on silicon substrate using comb line and RF MEMS variable capacitor, enabling compatibility with planar IC technology. A conventional CPW on a substrate consists of a central strip conductor with semi-infinite ground planes on either side. A comb line is etched on the signal line of the CPW and the MEMS bridge capacitor is put on the same line in shunt. Tunability of the filter is achieved by putting the MEMS bridge in either up or down state. The rejection at the centre frequency of stop bands are around ?40.24 dB for down state and ?38.21 dB for up state of the bridge. A low insertion loss, as low as ?0.68 dB, is obtained in the pass band. The proposed device structure is simulated using ANSOFT HFSS v13^® for RF analysis and COVENTORWARE (2008)^® for mechanical and electromechanical characterization, both static and transient analysis.     

Wideband coplanar waveguide RF probe pad to microstrip transitions without via holes

A novel via-less coplanar waveguide (CPW) to microstrip transition is discussed and design rules based on simulations and experimental results are presented. This transition demonstrates a maximum insertion loss of 1 dB over the frequency range from 10 GHz to 40 GHz with a value of 0.4 dB at 20 GHz. This transition could find a variety of applications due to its compatibility with RF systems-on-a chip, low loss performance, low cost and its ease of fabrication.     

CPW to Rectangular Waveguide Transition on an ${hbox{LiNbO}}_{3}$ Substrate

This paper presents transition from coplanar waveguide (CPW) to rectangular waveguide for $W$ -band (75–110 GHz) operations. The waveguide consists of a cosine-shaped fin extending from the upper waveguide wall onto the CPW signal electrode. The design features direct integration of the waveguide with opto-electronic devices on lithium niobate $({hbox{LiNbO}}_{3})$ for the applications of millimeter wave to optical signal processing. Simulations and measurements show that the model works very well over the entire $W$-band. Measurements of fabricated devices have yielded return loss of more than 10 dB and insertion loss of about 2.8 dB over the operating bandwidth.      

Wide-band superconducting coplanar delay lines

Two 25-ns high-temperature superconductor delay lines with novel double-spiral meander line structures were fabricated and measured, one based on the conventional coplanar waveguide (CPW) and the other based on the conductor-backed CPW. Compared with other published studies, the performance of the Conductor-backed CPW delay line is among the best in terms of the widest resonance-free band (2-18 GHz), low insertion loss (0.06 dB/ns at 60 K and 10 GHz), small ripple (<1 dB up until 16 GHz), and small dispersion (<2 ns in the variation of group delay between 2-18 GHz). This is also the first coplanar delay line successfully demonstrated without using wire bonding. The reflecting elements in the delay lines were identified through time-domain measurements. Full-wave simulations were performed to compare the double-spiral meander-line structure with conventional double-spiral line, and to identify the geometric factors restricting the bandwidth of the double-spiral meander line.     

A Broadband CPW-to-Microstrip Modes Coupling Technique

A broadband vertical transition from coplanar waveguide (CPW)-to-microstrip modes is presented. The transition has a double resonance and can be tuned for very wide-band operation. The CPW-to-microstrip modes coupling technique is useful for the vertical integration of multi-layer millimeter-wave circuits, packaging and antenna feeding networks. A vertical transition has been fabricated on 100 μm silicon substrate for operation at W-band frequencies and shows less than 0.3 dB of insertion loss and better than 12 dB of return loss from 75 to 110 GHz. A 94 GHz CPW-fed microstrip antenna showing a 10-dB bandwidth of about 30 % has been built using the same transition technique.