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A model describing the time constant of a transmission-line integrator is presented. By representing the formulations of integrators in the discrete-time (or Z) domain, we implement the integrators with equal-length transmission lines. Three integrators with different time constants and frequency bands are built and tested. The experimental results are in good agreement with theoretical values. Index Terms--Equal-length line, microwave integrator, time constant, Z transforms.

Simple and accurate formulations are employed to represent discrete-time infinite impulse response processes of both first- and second-order differentiators in the Z-domain. These formulations, in conjunction with the representations of transmission-line elements in the Z-domain, lead to transmission-line configurations that are eligible for wide-band microwave differentiators. Both the first- and second-order differentiators in microstrip circuits are implemented to verify this method. The experimental results are in good agreement with simulation values. Index Terms--Equal-length line, microwave differentiator, Z-transforms.

A synthesizing method is presented to design and implement digital dual-band filters in the microwave frequency range. A dual-band filter consists of a bandstop filter and a wide-band bandpass filter in a cascade connection, wherein the transfer functions of both the bandpass filter and bandstop filter are expressed in the Z domain. The bandstop filter is implemented by using a coupled-serial-shunted line structure, while the wide-band bandpass filter is constructed by using a serial-shunted line configuration. In particular, the bandwidth of each passband of the dual-band filter is controllable by adjusting the characteristics of both the bandpass filter and bandstop filter. By neglecting the dispersion effect between microstrip lines of different widths over a wide bandwidth, a dual-band filter is realized in the form of microstrip lines and its frequency responses are measured to validate this method. Index Terms--Bandstop filter, dual-band filter, microstrip lines, wide-band bandpass filter, Z domain.

ABSTRACT In this letter, a novel coupling configuration for a stepped impedance resonator (SIR) is proposed and used in the design of triple-passband filters with a small circuit. The filter was designed to have higher selectivity by manipulating direct coupling, input, and output external quality factors of the SIR. The second and third resonant frequencies can be tuned by adjusting the structural parameters. To verify the proposed configuration, triple-passband Chebyshev filters were designed and implemented using microstrip lines. The consistency between the measured results and full-wave simulation prediction validated that the configuration of the proposed filters is feasible. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:124-127, 2015 [ABSTRACT FROM AUTHOR]