Ultra-wideband balun and power divider using coplanar waveguide to microstrip transitions

An ultra-wideband transition from coplanar waveguide (CPW) to a pair of microstrip lines is presented in this letter. It is shown that the proposed transition can be used to devise an ultra-wideband T-junction power divider with equally split in-phase output signals. More importantly, it is demonstrated that the out-of-phase magnetic currents in the slots of the CPW can be utilized to achieve an out-of-phase power divider or a balun. Both the T-junction power divider and the balun benefit from compact size and good performance over an ultra wide frequency band from 3 to 16 GHz. Prototypes of both proposed devices are fabricated and measured to provide an experimental verification on the concept and numerically predicted features.     

A coplanar probe to microstrip transition

A transition between a coplanar probe and a microstrip transmission line is reported. The transition is significant in that it does not require substrate via holes. A set of microstrip impedance standards was developed for the purpose of de-embedding the transition. The latter is suitable for measuring the S parameters of a number of low-cost monolithic microwave integrated circuits with coplanar probes     

The picosecond pulse transmission on the conductor-backed coplanar waveguide with via holes

-The picosecond pulse propagation on the conductor-backed coplanar waveguide (CBCPW) with via holes is investigated. For this purpose, an empirical dispersion formula by fitting measurement data is proposed and Gaussian picosecond pulse transmissions on the CBCPW with via holes are simulated. By comparing the modeling data with the simulation result by the reported formula, we verify the usefulness and effectiveness of the proposed expression.     

Wideband coplanar waveguide-to-rectangular waveguide transition using fin-line taper

This letter introduces a new wideband coplanar waveguide-to-rectangular waveguide transition. The transition uses a uniplanar circuit in line with the waveguide, which eases the design and fabrication. The design does not require airbridges. Simulations and measurements of X-band (8.2-12.4 GHz) transitions based on both a low- and high-permittivity material (/spl epsiv//sub r/= 2.33 and 10.8) show that the transition works fine over the full frequency band. For /spl epsiv//sub r/= 2.33 the measured return and insertion loss of a back-to-back transition are more than 16 dB and less than 0.4dB, respectively. The corresponding values for /spl epsiv//sub r/= 10.8 are more than 10 dB and less than 1.0 dB, respectively, over 90% of the frequency band. The measured insertion loss values indicate losses of less than 0.14 dB and 0.36 dB at the center frequency for a single transition on a substrate with /spl epsiv//sub r/= 2.33 and 10.8, respectively.     

Grounding microstrip lines with via holes

Grounding microstrip circuits with via holes is an established technology and modeling isolated via holes with analytical models is well known. However, the availability of electromagnetic field solvers provides an opportunity to model via holes and the metallization surrounding them in a more realistic fashion. Calculated equivalent inductances for single and double via hole configurations are presented. A microstrip interdigital filter with grounded resonators provides experimental verification     

W波段反对称渐变探针过渡转换的设计

介绍了一种反对称渐变波导微带探针过渡结构,采用高频仿真软件HFSS仿真分析了这个波导微带过渡结构在W频段的特性,并对影响过渡性能的几个因素进行了敏感性分析,得出了可供工程应用参考的设计曲线。在全波导带宽内,实现了插入损耗小于0.088 dB,回波损耗大于27 dB。该结构具有宽频带、结构简单和易加工等优点,可广泛用于毫米波固态电路系统中。     

Full wave modeling of microstrip via holes

A rigorous full-wave analysis of microstrip via hole grounds is performed using a three-dimensional mode-matching method associated with a suitable segmentation technique. Theoretical results are compared with measured data showing excellent agreement.     

一种V波段波导-微带对极鳍线过渡结构的设计研究

文章研制了一款V频段的波导微带转换器,该转换器采用对极鳍线过渡结构,并提出了一种抑制谐振及基片安装引起的高次模的设计方案。实际测试回波损耗小于-21 dB,插入损耗小于1.6 dB。     

Surface-to-surface transition via electromagnetic coupling ofmicrostrip and coplanar waveguide

A structure which forms a transition from coplanar waveguide on one substrate to microstrip on another is described. Energy is transferred via electromagnetic coupling rather than with wire bonds. A full-wave formulation along with the theory of asymmetrically coupled lines is used to analyze the transition. Two model transitions were built and tested. Theory and measurement show good agreement when the coupler length to width ratio is larger than 0.6     

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)     

RF characterization and isolation properties of mesoporous Si by on-chip coplanar waveguide measurements

We report on the broadband electrical characterization of thick mesoporous silicon layers used as RF microplates for on-chip integration of high-Q passive devices in a CMOS-compatible process. To measure the RF losses of the microplate we have fabricated several designs of Coplanar Waveguides (CPWs), for form-factors relevant to the sizes of on-chip passive RF devices, on thick mesoporous Si layers (RF microplates) of various thicknesses, and we compared the results with those obtained from similar CPWs integrated directly on the p-type Si substrate. For maximum measurement sensitivity of the loss, the CPWs were designed to be very good transmission lines matched to 50 Ω port impedances. We also characterized the grown mesoporous Si by performing electromagnetic simulations of the structure and identifying the measured and simulated S-parameters over a broadband frequency region, for the appropriate simulator input of complex permittivity. The measured results show that, for CPW features commensurate with the scale of on-chip RF passive devices, a 50-μm-thick mesoporous Si layer on the Si substrate reduces the losses to 1/6th–1/4th of the values corresponding to a p-type Si substrate, showing that mesoporous Si is an excellent material for CMOS-compatible on-chip integration of high-Q passive devices.     

横向Ka波段波导微带探针过渡的设计和优化

介绍了一种横向Ka波段宽带波导-微带探针过渡的设计,基于有限元场分析软件Ansoft HFSS对该类过渡的设计方法进行了研究。最后给出了Ka波段内的优化数据。仿真结果表明,该宽带波导-微带探针过渡在26.5G~40GHz内插入损耗小于0.065 dB,达到了设计目标。     

Wideband coplanar stripline to double-sided parallel-strip line transition

A novel wideband transition between the coplanar stripline and the double-sided parallel-strip line is presented. The simple transition consists of two tapered lines, one located on the top layer and one tapered line on the bottom layer. Through the proposed transition, horizontally distributed electric fields of the coplanar stripline become rotated by 908 to match the vertically distributed fields of the double-sided parallel- strip line. Simulated and measured results of a back-to-back transition show good agreement.     

Effect of coplanar probe pad design on noise figures of 0.35 μmMOSFETs

The effects of different coplanar ground-signal-ground (GSG) probe pads on the noise figure characteristics of submicron MOSFETs are presented. Devices with top-level metal as probe pads shielded by grounded bottom-level metal possess the most appropriate probe pad structure for characterising the noise performance of MOSFETs. Equivalent circuits of the probe pads are used to explain the different noise behaviours     

Q波段微带到带状线垂直过渡结构

层间垂直过渡结构通常被用来实现组件结构的小型化和高密度设计,在毫米波电路布线中起着不可或缺的作用。本文设计了一种可用于Q波段的微带线到带状线的垂直过渡结构,在微带线的末端采用“水滴”匹配结构,以金属通孔连接传输线的形式进行射频信号的垂直传输。运用三维高频电磁仿真软件(HFSS)建立该结构,并与其他类似结构进行性能仿真比对。优化结果表明,这种结构在42~47 GHz频带范围内,反射系数小于-20 dB,带内插入损耗优于0.3 dB,可以满足工程应用的要求。相比同类型的其他垂直过渡结构,本文结构在减小占用面积的同时保持了良好的传输性能。     

一种四频段多L型缝隙天线研究与设计

设计了一款共面波导馈电的多L型缝隙天线.通过在一个三角形辐射贴片上开L形缝隙实现多频的性能, 优化调整L形缝隙的大小以及相关参数可以灵活控制其每个频段的带宽.该天线具有多频带、小型化等特性, 通过共面波导馈电和采用高介电常数基板的方法降低了天线的谐振频率, 使得天线可以工作在更低频段.通过电磁仿真软件HFSS13.0对天线性能进行大量仿真实验与计算, 该天线在回波损耗小于-10 dB以下时, 其工作频段为1.254~1.276 GHz、1.537~1.623 GHz、1.804~1.845 GHz、2.097~3 GHz.该天线的结构简单、易于加工实现, 能够满足GPS、第三代第四代移动终端内置天线的小型化和多频段的要求.     

Analytical expression for the input impedance of a microstrip probe in waveguide

We present a closed-form expression for the the input impedance of a microstrip probe in a rectangular waveguide. The probe extends only part way across the waveguide and is therefore compatible with RF components that require an open circuit at low frequencies. Our analysis is based on the spectral-domain method and is able to take into account the orientation of the antenna with respect to the direction of propagation. We have examined the validity of our model by carrying out extensive impedance measurements at 5GHz. In those cases where the probe did not extend more than half way across the waveguide, excellent agreement was obtained. We show that the bandwidth of a probe that stretches only part way cross the waveguide is very much greater than the bandwidth of a probe that stretches all of the way across the waveguide and that is earthed at both ends. Moreover, the input resistance is lower and more suited to submillimetre-wave detectors such as SIS tunnel junctions. Our expression suggests that it should be possible to develop low-impedance, wideband probes for nearlydouble-height waveguide, and this implies that the upper frequency limit to which probes and waveguides can be manufactured can be extended well into the THz frequency range. A related, and often neglected consideration, is that the ohmic loss associated with an oversized waveguide is very much smaller than the ohmic loss associated with a reduced-height waveguide.     

Analysis of microstrip line to waveguide end launchers

The expression for impedance is derived using the self-reaction concept with the assumption of a sinusoidal current distribution existing in the conductor loop. Three different cases of end launchers are computed for their corresponding input impedances. Comparison between calculated and measured input return loss of an end launcher shows good agreement between theory and experiment at Ka-band frequencies     

Novel coplanar waveguide to slotline transition on high resistivity silicon

Two novel coplanar waveguide (CPW) to slotline transitions have been fabricated and tested on high resistivity silicon. The first transition uses an air bridge to couple RF power from the CPW line to the slotline and has the entire circuit on the top side of the wafer. In the second transition, the grounded CPW (GCPW) line and the slotline are on opposite sides of the wafer and are coupled electromagnetically. The measured average insertion loss and return loss per transition are better than 1.5 and 10 dB, respectively, with a bandwidth greater than 30% at C-band frequencies.<>     

Comparison of models for the probe inductance for a parallel-plate waveguide and a microstrip patch

Four different models for the probe inductance of a circular probe in an infinite parallel plate waveguide are studied. These models include a uniform-current model, a cosine-current model, a gap-voltage source model, and a coaxial-frill model. These different models treat the vertical variation of the fields within the substrate and the field of the coaxial feed with varying degrees of rigor. Numerical high frequency structure simulator data are also compared with the results of these models in order to draw reliable conclusions about the accuracy of these models as a function of the substrate thickness. A simple computer-aided design formula for the probe inductance of a coaxial feed probe for a rectangular microstrip patch antenna is also introduced.