Slow-wave Microstrip Research Articles

Design of PIN diode controlled variable attenuator using slow wave microstrip lines

We describe a simple PIN-diode-controlled variable attenuator that employs a 0-dB branch-line directional coupler, and present a method to reduce the size using slow-wave microstrip lines. At the center frequency, the attenuation monotonically varied from 0.7 to 23 dB with the control voltage. By using slow-wave microstrip lines, we achieve a 60% size reduction compared to a conventional structure. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 323–327, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21159

A size reduced reflection-mode phase shifter

We describe a reflection-mode phase shifter which exhibits a large phase-shift range and is size-reduced by using slow-wave microstrip lines. We characterize its response between 1.9 and 2.1 GHz and achieve a more than 300° phase shift with less than 3.5-dB insertion loss, with 435° at its center frequency. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 457–459, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21198

Analysis and circuit model of a multilayer semiconductor slow-wave microstrip line

An analytical single-layer reduction quasi-static formulation to accurately compute all the line parameters of metal insulator semiconductor (MIS) and Schottky contact multilayer slow-wave microstrip lines is presented. It is valid for a wide range of parameters and its validity is compared with the full-wave spectral domain analysis technique. We also obtain a circuit model, which is able to accurately explain the experimental results, including dispersion at the lower end of the frequency range, for both the MIS and Schottky contact microstrip lines. Useful data to design passive components based on these lines are also presented.

A new type of slow‐wave 1D PBG microstrip band‐pass filter

AbstractIn this paper, a new type of slow‐wave 1D PBG microstrip band‐pass filter with a half‐wavelength linear resonator is introduced. Reduction of the central frequency (slow‐wave effect) is over 50%, as compared to the conventional band‐pass filter of the same type. Additional coupling is over tuning narrow lines that can be used to regulate the filter's performance. In addition, it has very good S11 parameters and low losses in the band‐pass. Simulation and experimental results are in good agreement. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 201–203, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10868

Propagation characteristics of suspended MIS coupled slow‐wave microstrip lines

AbstractThe single‐layer reduction (SLR) formulation is presented to compute the propagation characteristics, that is, the slowing factor (normalized phase constant) and the attenuation constant of the even and odd modes of the suspended MIS coupled slow‐wave microstrip lines. The proposed structure is suitable for the design of a compact high‐directivity coupler. For the standard coupled MIS microstrip line the SLR computes the slowing factor with deviation about 1% and the attenuation constant with 0.005 dB/mm difference against reults of the spectral domain analysis (SDA). The SLR is as accurate as the SDA; however, computationally it is much faster than the SDA. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 403–405, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10476

Electric-magnetic-electric slow-wave microstrip line and bandpass filter of compressed size

This paper presents a novel integrated microstrip low-loss slow-wave line. The new microstrip replaces the conventional metal strip by composite metals paralleling the electric surface and magnetic surface (MS). The MS made of an array of coupled inductors shows a high-impedance state in the stopband, below which the propagation properties can be well controlled by varying the dimensions of the electric surface and MS. The dispersion curves obtained by matrix-pencil analyses closely correspond to those obtained by scattering-parameter extraction. Theoretical results, as confirmed experimentally, indicate that an increase of over 60% in the slow-wave factor can be achieved without sacrificing propagation losses, using the proposed structure. This electric-magnetic-electric (EME) microstrip is insensitive to the alignment position of the periodical structure, and can be constructed using conventional printed-circuit-board fabrication processes and integrated with other microwave components in a multilayered circuit. A compact EME bandpass filter (BPF) with suppressed harmonic responses is presented. The length of the filter is reduced by 26%, and the measured insertion loss and fractional bandwidth is comparable to that of a conventional microstrip BPF on the same substrate.

Perforated microstrip structure for miniaturising microwave devices

The perforated slow-wave microstrip is proposed for high-frequency microwave devices and characterised experimentally and theoretically up to 7 GHz. The perforated structure is realised with a periodic-inductive-section-maintained uniform edge-shape. The slow-wave factor is demonstrated to be 1.2 times larger than that of a conventional microstrip over a wide frequency range. The perforated slow-wave microstrip shows reduction of physical length and superior quality-factor. The proposed structure is easier to fabricate than other slow-wave structures, which require multilayer substrates.

Propagation characteristics of Schottky contact suspended slow-wave microstrip line

The single-layer reduction (SLR) model computes the normalized phase constant (/spl beta///spl beta//sub 0/), dielectric loss (/spl alpha//sub d/), and conductor loss (/spl alpha//sub c/) for the Schottky contact slow-wave microstrip (SCSM) line with accuracy about 2.0% for /spl beta///spl beta//sub 0/, and within 0.01 dB/mm for the total loss (/spl alpha//sub t/=/spl alpha//sub d/+/spl alpha//sub c/) as compared against the experimental results. The SLR model has been further used to analyze the normal and abnormal characteristics of a proposed Schottky contact suspended slow-wave microstrip (SCSSM) line with 22% increase in /spl beta///spl beta//sub 0/ over the normal SCSM line. The SCSSM line could be useful in the lower range of RF for the development of compact components.

A novel low-loss slow-wave microstrip structure

A low-loss slow-wave microstrip line using a periodic structure in the ground plane is presented. The periodic structure is realized with metal pads etched in the ground plane connected by thin lines to form a distributed LC network. The slow-wave factor is demonstrated to be 1.2-2.4 times larger than that of conventional microstrip lines over a wide frequency range. Due to the unique design of the structure, low insertion loss comparable to conventional microstrips has been achieved. The proposed structure is easier to fabricate than other slow-wave devices which require multilayer substrates or very fine features.

Slow wave propagation using interconnections for IC technologies

A new microstrip slow wave transmission line, based on a periodic structure made with the two metallic levels used in ICs, is described. Using on-wafer measurements, an effective permittivity as high as 20 in a wide microwave frequency range is reported. The transmission line has also been measured to obtain the characteristic impedance and the losses. Using the basic periodic structure theory the propagation constant of this media has been computed and good agreement has been obtained with that of the measurement. This slow wave structure is very promising for use in MMIC because of its very compact design.

Characteristics of Multiconductor, Asymmetric, Slow-Wave Microstrip Transmission Lines

Spectral-domain technique has heen applied to analyze multiconductor, asymmetric, slow-wave microstrip lines. It is observed that 1) the coupled slow-wave microstrip line on a two-layer substrate may have substantially different propagation constants for even and odd modes and 2) the slow-wave factor of an odd mode of coupled microstrip lines on a three-layer substrate may be equal to or larger than that of an even mode under appropriate conditions. This presents the flexibility to realize a large variety of passive components, such as directional couplers, phase shifters, and attenuators.

Slow-Wave Characteristics of Ferromagnetic Semiconductor Microstrip Line

A new slow-wave microstrip line made of a ferromagnetic semiconductor (FMS) substrate is proposed and its characteristics are discussed. Another possibility of a slow-wave microstrip line by a ferromagnetic (FM) substrate is also described in this paper. It is shown that these structures have more desirable and flexible guided wave properties than the conventional metal-insulator-semiconductor (MIS) microstrip line.

Slow-wave directional coupler and its applications

The directional coupler and the traveling-wave directional filter made of coupled slow-wave microstrip lines are proposed and their characteristics discussed. These structures exhibit interesting characteristics not readily available in conventional transmission lines.

Slow-wave power divider

A novel power divider made of a coupled slow-wave microstrip line is proposed and its characteristics discussed. The difference between the attenuation constants for even and odd modes in a coupled slow-wave microstrip line are successfully used to eliminate a resistor.

Characteristics of coupled slow-wave microstrip lines

The spectral-domain technique has been applied to investigate the characteristics of coupled slow-wave microstrip lines.