Rainee N. Simons

Theoretical and experimental characterization of coplanar waveguide discontinuities for filter applications

A full-wave analysis of shielded coplanar waveguide (CPW) two-port discontinuities based on the solution of an appropriate surface integral equation in the space domain is presented. Frequency-dependent scattering parameters for open-end and short-end CPW stubs are computed using this method. The numerically derived results are compared with measurements performed in the frequency range 5-25 GHz and show very good agreement. From the scattering parameters, lumped-element equivalent circuits have been derived to model the discontinuities. The inductors and capacitors of these models have been represented by closed-form equations, as functions of the stub length, to compute the circuit element values for these discontinuities. >

Modeling of some coplanar waveguide discontinuities

Lumped equivalent circuit models for several coplanar waveguide (CPW) discontinuities such as an open circuit, a series gap in the center conductor, and a symmetric step in the center conductor are presented, and their element value are given as a function of the physical dimensions of the discontinuity. The model element values are de-embedded from measured S-parameters, and the effects of the center conductor width and the substrate thickness on the equivalent circuit element values are obtained. The characteristics of a CPW right-angle bend using a compensation technique are presented. The frequency dependence of the effective dielectric constant is measured and compared to computed values. >

A new rectangular waveguide to coplanar waveguide transition

A novel rectangular-waveguide-to-coplanar-waveguide transition is described. The transition uses a ridge in one of the broad walls of the waveguide and a nonradiating slot in the opposite wall to split and rotate the electromagnetic fields of the rectangular waveguide TE/sub 10/ mode into the coplanar waveguide (CPW) fields. This transition should permit the use of CPW-based circuits in the millimeter-wave frequency range and the development of microwave probes above 50 GHz for fast and inexpensive testing of the millimeter-wave circuits.<<ETX>>

Modeling of coplanar stripline discontinuities

The paper presents a technique to obtain lumped equivalent circuit models for typical coplanar stripline (CPS) discontinuities such as an open circuit, a short circuit, and a series gap in one of the strip conductors and gives their element values as a function of the discontinuity physical dimensions for a specific substrate. The model element values are determined from the discontinuity scattering parameters which are de-embedded from the measured scattering parameters using a thru-reflect-line (TRL) algorithm. In addition, the resonant frequency of a spur-slot is presented as a function of the spur length. The experimental results are validated by data obtained using the finite-difference time-domain (FDTD) technique.

On-wafer characterization of millimeter-wave antennas for wireless applications

This paper demonstrates a deembedding technique and a direct on-substrate measurement technique for fast and inexpensive characterization of miniature antennas for wireless applications at millimeter-wave frequencies. The technique is demonstrated by measurements on a tapered slot antenna (TSA). The measured results at Ka-band frequencies include input impedance, mutual coupling between two TSAs, and absolute gain of TSA.

Coplanar-waveguide aperture-coupled microstrip patch antenna

The performance characteristics of a coplanar waveguide (CPW) aperture-coupled microstrip patch antenna were investigated experimentally. A grounded CPW with a series gap in the center strip conductor was used to couple microwave power to the antenna through an aperture in the common ground plane. Results indicate good coupling efficiency and confirm the feasibility of this feeding technique.<<ETX>>

Coplanar stripline propagation characteristics and bandpass filter

In this paper, a coplanar stripline bandpass filter is developed. The propagation characteristics of the coplanar stripline used for the construction of the filter are presented in the form of phase constant and attenuation constant. The filter is characterized experimentally as well as theoretically by use of the finite-difference time-domain (FDTD) technique. The agreement between the measured and modeled filter characteristics is very good.

Integrated uniplanar transition for linearly tapered slot antenna

This paper presents the design, fabrication, and numerical modeling of two new uniplanar microstrip-to-coplanar strip (CPS) line transitions and a new variant of the linearly tapered slot antenna (LTSA). This new variant with an integrated uniplanar microstrip-to-coplanar strip line feed is called a V-LTSA. The advantages of these transitions in packaging and monolithic microwave integrated circuits (MMIC) integration are listed. The two transitions and the feed are modeled using finite difference time domain (FDTD) method. The overall agreement between the measured and modeled return-loss and insertion-loss characteristics of two back-to-back transitions is good. The resonance frequencies predicted by the FDTD method are within a few percentage points of the measurements. Furthermore, the V-LTSA with the feed is experimentally shown to have a wide return loss (/spl les/-10 dB) bandwidth, good radiation patterns, and low cross-polarization. The gain of the V-LTSA is 9 dB at the design frequency of 10 GHz. A proof-of-concept package to house the feed is experimentally evaluated and shown to have negligible effect on the antenna characteristics. This type of antenna readily integrates with MMIC packages in an array having a brick architecture. The V-LTSA has potential applications in phased arrays. >

Channelized coplanar waveguide: discontinuities, junctions, and propagation characteristics

The authors present lumped-element circuit models for several CCPW (channelized coplanar waveguide) discontinuities, together with their element values as a function of frequency. The discontinuities characterized are an open circuit and a right-angle bend. The measured frequency dependence of the effective dielectric constant, epsilon (eff), and the unloaded quality factor, Q, are also presented for CCPW lines fabricated on epsilon (r)=2.2+or-0.02 RT/Duroid 5880, epsilon (r)=6.0+or-0.15 RT/Duroid 6006, and epsilon (r)=10.2+or-0.025 3M Epsilam-10 substrates. Attention is then given to the design and characterization of CCPW T-junction and 1-to-3 in-phase, matched power divider. The performance of a novel coax-to-CCPW in-phase, N-way radial power divider circuit is also presented.<<ETX>>

Experimental and theoretical study of parasitic leakage/resonance in a K/Ka-band MMIC package

In this paper, electromagnetic (EM) leakage and spurious resonances in a K/Ka-Band (18-40 GHz) MMIC hermetic package designed for a phase shifter chip are studied using the finite element method (FEM) and the numerical simulation results are compared with the measured data. Both the measured and calculated data indicate several spurious resonances in the 18-24 GHz region and the origin of this phenomenon is identified by virtue of the modeling capability of the FEM. Moreover, the effect of dc bias lines, bond wires, shielding, and the asymmetry of the package on electrical performance are closely examined. In addition, the effect of adding a resistive coating to the inside surface of the package lid and also the use of dielectric packaging materials with very high loss tangent are studied in view of the suppression of the spurious resonances. Finally, design guidelines for the improved package are presented.