Suspended Substrate Microstrip Line Research Articles

Design of LPF using suspended substrate microstrip lines as high‐Z sections for stopband extension

ABSTRACTThis article introduces the use of suspended substrate microstrip lines (SSMLs) as high‐Z sections in the design of lowpass filters (LPFs) to extend the stopband. The SSMLs are formed by etching slots on the backside of microstrip lines and placing the substrate on an aluminum base with grooves that cover these slots. The higher characteristic impedance property of SSMLs brings about not only shorter length for high‐Z lines but also a larger high‐to‐low impedance ratio, thus deepening the stopband suppression and shifting the spurious passband away. As a demonstration, a wide stopband LPF combining this structure with hammer‐shaped stubs is designed, fabricated, and measured. The 20 dB stopband is obtained from 1.45 to 11.77 GHz. Compared with reported LPFs, this shows the widest fractional bandwidth (FBW) of 156% without sacrificing other performances. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1204–1207, 2016

Fourier transform analysis of a unilateral fin line and its derivatives

A unilateral fin line and its derivatives are analysed utilising the Fourier transform and mode-matching. The image theorem is used to transform a unilateral fin line into an infinite number of suspended substrate microstrip lines. New rigorous dispersion relations are obtained in fast-convergent series, which are efficient for numerical computation. Calculations are performed to illustrate the rate of convergence and accuracy of the series solution.

Fast microchannel plate detector with an impedance matched anode in suspended substrate technology

Fast particle detectors with subnanosecond pulse widths are key elements in modern time-of-flight mass spectrometers. Typically, an impedance matched transmission line from the extended anode to the coaxial cable is necessary to obtain fast pulses. We present an approach using a planar geometry for the transmission line. Thereby, the impedance match is realized with a transition from a 50 Ω suspended substrate microstrip line to a coaxial 50 Ω line. A prototype with an active area of 1.8 cm diameter including a strategy to reduce peak ringing was built and tested. The mean pulse width measured with a 1 GHz analog oscilloscope was 520 ps (full width at half maximum) with a rise time of 380 ps. The robust, compact, and low-weight design of the detector is well suited for an application in space, where weight, space, and power consumption are very limited resources.

Higher order modes in suspended substrate microstrip lines

The characteristics of both types of higher order modes in suspended substrate microstrip lines are evaluated using spectral domain analysis. Also, the cutoff frequencies of the first two higher order modes are computed and the operation bandwidth is evaluated. The obtained results are compared with some estimated values given by other authors. Finally, design curves are reported for practical suspended substrate microstrip line structures. >

Computer-aided design for finlines and suspended-substrate microstrip lines

The computer-aided design of finlines and suspended-substrate microstrip lines are investigated. The numerical results of this paper show good agreement with those computed by other techniques for unilateral finlines and open suspended microstrip lines. The approach of this paper may be used to the computer-aided design of many other kinds of transmission lines and circuits for millimeter wave applications.

Computation of the dispersion characteristics of a shielded suspended substrate microstrip line

The dispersion characteristics of a shielded suspended substrate microstrip line are calculated using five different sets of basis functions for the current distributions. Their comparison leads to the more suitable basis functions for the acquisition of fast and accurate results for frequencies up to 100 GHz. >

Propagation characteristic for a suspended substrate microstrip line with pedestal

In the letter the full-wave analysis of a suspended substrate microstrip line with pedestal is investigated for the first time. Two auxiliary problems are constructed for obtaining the fields above and below the plane of the pedestal support. The characteristic equation is derived using the spectral Galerkin method.

Computer-aided design models for broadside-coupled striplines and millimeter-wave suspended substrate microstrip lines

Models were derived from the results of conformal transformation on homogeneous stripline, the equivalence of the odd-mode with the quasi-TEM mode of covered microstrip line, and logarithmic regression of spectral-domain results. Effects of finite strip thickness have been taken into account. These models are fully compatible with the needs and trends of computer-aided and programmable-calculator-aided microwave and millimeter-wave integrated circuit design.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>