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In this work, a new method for stopband extension in both open-ended and interdigital parallel-coupled line filters is presented. This method is intended for the suppression of spurious bands which inherently appear in the stopband of this kind of filters. The multispurious suppression is achieved by means of a precise control of the coupling between resonators at unwanted resonant frequencies. The coupling section lengths between successive resonators are used as control parameters to obtain the required couplings. The dependence of the coupling coefficients on coupling section lengths at resonant frequencies is given by closed expressions, obtained following an energetic coupling approach. Several microstrip bandpass filters designed following the new method are presented as examples. These filters feature wide spurious-free bands with high rejection levels. [ABSTRACT FROM AUTHOR]

In this study, the design of parallel-coupled line bandpass filters (BPFs) is investigated from an energetic coupling theory approach. The proposed filter design process allows the design of BPFs with improved characteristics. In particular, it is possible to implement filters with reduced occupation area, larger passband bandwidth and improved rejection performance. This is accomplished by controlling the coupling coefficient between resonators by means of the coupling section length. The suggested design technique is validated through the design, fabrication and measurement of several coupled line microstrip BPFs centred at 2.0 GHz. [ABSTRACT FROM AUTHOR]

A class of microstrip lowpass filter (LPF) with a sharp‐rejection, ultra‐broad stopband is reported. It employs rat‐race directional couplers properly arranged to operate as bandstop transversal filtering sections (TFSs). The theoretical foundations of this LPF approach are described, and the performance control of its building bandstop TFS is verified. Moreover, a proof‐of‐concept microstrip LPF prototype with a 3 dB cutoff frequency of 1 GHz and a 20 dB stopband up to 5.86 GHz has been built and tested. [ABSTRACT FROM AUTHOR]

This paper proposes a method to obtain the isothermal static DC curves of microwave FET power amplifiers, avoiding the use of pulsed measurements and accounting for the self-heating problem in this type of device. The method requires the determination of the thermal resistance of the device under test and the measurement of its static DC curves under different ambient temperatures. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 378–380, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20475 [ABSTRACT FROM AUTHOR]

A class of microstrip lowpass filter (LPF) with a sharp-rejection, ultrabroad stopband is reported. It employs rat-race directional couplers properly arranged to operate as bandstop transversal filtering sections (TFSs). The theoretical foundations of this LPF approach are described, and the performance control of its building bandstop TFS is verified. Moreover, a proof-of-concept microstrip LPF prototype with a 3 dB cutoff frequency of 1 GHz and a 20 dB stopband up to 5.86 GHz has been built and tested. [ABSTRACT FROM AUTHOR]

A new continuous-wave linear frequency modulated radar scheme, which allows the accomplishment of high resolution radar images independently of the target position, is presented. Range resolutions around 15 cm can be achieved transmitting a gigahertz of bandwidth with a maximum distance of 15 km. [ABSTRACT FROM AUTHOR]