Grounded Coplanar Waveguide Research Articles

Finite ground coplanar waveguide (FGC) low loss, low coupling 90-degree crossover junctions

Microwave and millimeter-wave integrated circuits and RF distribution networks often require two transmission lines to cross over each other. In this paper, experimental measurements and three-dimensional (3-D) finite difference time domain analysis are used to thoroughly characterize coplanar waveguide (CPW) and finite ground coplanar waveguide (FGC) 90-degree crossover junctions. It is shown that FGC crossover junctions have approximately 15 dB lower coupling than CPW crossover junctions. Furthermore, it is shown that the FGC junctions do not excite the parasitic slotline mode, whereas, the CPW junctions do excite the slotline mode. The results presented indicate that the FGC crossover junction is easier to implement and has better characteristics than the CPW crossover junction.

W-band micromachined circuit combining networks

In circuit-combining networks, low-loss interconnecting transmission lines are pivotal in reducing excess loss. Micromachined finite ground coplanar waveguides are used in this study as low-loss interconnects showing significant improvements in line loss while maintaining 50-/spl Omega/ characteristic impedance. Wilkinson power dividers, reactive tee junctions, and right-angle bends are combined with micromachined interconnects in 1:2, 1:4, and 1:8 power-dividing networks and show measured loss reduction of 0.3-1.0 dB depending on circuit type and size from 85 to 95 GHz.

A CPW T-resonator technique for electrical characterization of microwave substrates

An impedance independent method is proposed using a finite ground coplanar waveguide (CPW) T-resonator to electrically characterize microwave materials. Silicon-based CPW T-resonators are designed and measured, with calibrated data agreeing well with other methods up to 30 GHz. Uncalibrated measurements produce dielectric constant and attenuation results within 3.7% and 25%, respectively, of those obtained with calibration. Hence, the CPW T-resonator can be used to provide rapid and accurate characterization of microwave substrates with unknown dielectric properties.

Tunable millimeter-wave filters using a coplanar waveguide andmicromachined variable capacitors

In this paper, new micromachined tunable bandpass filtersfor multi-band millimeter-wave telecommunication systems areproposed. Two types of millimeter-wave tunable filters have beenfabricated using micromachining technology and the responses of thefilters have been measured: one type is a two-pole lumped elementfilter and the other a two-pole resonator filter. The frequencytunability of the filter has been achieved by changing the gapbetween a common coplanar waveguide ground plate and a movablecantilever beam connected to the transmission line with acontrollable range of 2.5 µm. The deflection of the cantileverbeam has been measured with applied dc voltage. With the applied biasvoltage from 0 to 50 V, the fabricated filters have shown centerfrequency shifts of 0.6 GHz (2.3%) at 26.6 GHz and 0.8 GHz (2.5%)at 32 GHz for the lumped element and resonator filters, respectively.The mechanical lifetime of the fabricated gold cantilever structurehas been tested by observing the existence of the spring memoryphenomenon; there is no memory phenomenon or breakdown until arepeated actuation of 1.6×108 cycles.

FDTD analysis of a new transition from coplanar waveguide to rectangular waveguide

AbstractA rectangular waveguide fed by a grounded coplanar waveguide (GCPW) is investigated using the finite‐difference time‐domain (FDTD) method. A patch is used to couple energy to the rectangular waveguide (RW) by placing the waveguide opening around the patch. The coupling from the GCPW to the patch is accomplished via an open end. For a 10 dB return loss, a relative bandwidth of 14% is obtained for a GCPW‐to‐RW transition. A back‐to‐back GCPW‐to‐RW transition is analyzed, and is found to have good insertion‐loss characteristics, which verifies that power is indeed coupled to the waveguide. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 199–201, 2001.

Grounded coplanar waveguide-fed aperture-coupledcavity-backed microstrip antenna

Microstrip antennas aperture coupled to a grounded coplanar waveguide (GCPW) have been fabricated on a single layer substrate and studied experimentally and theoretically. Through-plated via holes are used to suppress spurious parallel plate modes. Measurements demonstrate that this antenna element has good performance for both bandwidth and radiation patterns. Calculations using a commercial CAD package are in reasonable agreement with measured data.

Mode conversion at GCPW-to-microstrip-line transitions

Mode conversion at the transition between grounded coplanar waveguide (GCPW) and microstrip line is demonstrated. Experimental results show the effect of overmoding in a conductor-backed coplanar waveguide on the transition behavior. A simple micromachining solution is used to cancel the parasitic modes triggered by the transition in the GCPW feed line. This results in an insertion loss of 0.3 dB and a return loss better than -18 dB from 75 to 110 GHz. The transition can prove very useful for millimeter-wave packaging and interconnects.

Coplanar waveguide radial line double stub and application to filter circuits

Coplanar waveguide (CPW) and grounded coplanar waveguide (GCPW) radial line double stub resonators are experimentally characterized with respect to stub radius and sector angle. A simple closed-form design equation, which predicts the resonance radius of the stub, is presented. Use of a double stub resonator as a lowpass filter or as a harmonic suppression filter is demonstrated, and design rules are given.

Effect of parasitic dielectric resonators on CPW/aperture-coupled dielectric resonator antennas

The effects of parasitic dielectric resonators on the HE11δ and HE13δ modes of a cylindrical dielectric resonator antenna (DRA) have been studied. The DRA was excited electromagnetically with a grounded coplanar waveguide through an aperture in the common ground plane. Strong couplings were observed for the HE11δ mode with the parasitic element superimposed on the driven DRA, and for the HE13δ mode with parasitic elements placed on both sides of the driven DRA. Results indicate significant enhancement in bandwidth for both modes, and good radiation patterns for the HE11δ mode.

Characteristics of a coplanar waveguide HEMT mount on GaAs substrate

In a special integrated coplanar waveguide HEMT mount, designed for a wide band (1-60 GHz) on-wafer measurement of the characteristics of HEMTs on GaAs, significant power loss as high as 30% of the input power over a range of frequencies is observed. This power loss is mainly attributed to the radiation through two via holes connecting the coplanar waveguide ground planes to the backside metallization in the mount. Based on this assumption, an approximate theoretical model is developed to substantiate the experimental observations. >

Coplanar waveguide aperture coupled patch antennas with ground plane/substrate of finite extent

Coplanar waveguide (CPW)/aperture coupled microstrip patch antennas constructed with ground coplanar waveguide (GCPW), finite coplanar waveguide (FCPW) and channelized coplanar waveguide (CCPW) are demonstrated. The measured characteristics show that the CCPW/aperture coupled microstrip patch antenna has the largest bandwidth, whereas the GCPW/aperture coupled microstrip patch antenna has the best front-to-back ratio.