Low-loss Bandpass Filter Research Articles

Low-loss and high-selectivity bandpass filter with harmonic suppression and piezoelectric transducer tuning

A low-loss and high-selectivity bandpass filter with harmonic suppression and piezoelectric transducer (PET) tuning is presented. At the 3.5 GHz passband, the insertion loss is 1.48 dB, and the transmission zeros at 3.05 and 4.08 GHz have rejection of 55 dB. The rejection at the 7 GHz second harmonic is 50 dB. A PET tunes the bandstop sections to obtain a tunable suppression (>45 dB) around the second harmonic from 5.35 to 7.8 GHz.

New wide-band DC-block cymbal bandpass filter

A new low-loss dc-blocking parallel-cascaded bandpass filter is presented. The filter is much easier to use and fabricate, more compact, and simpler to design than the conventional end- or parallel-coupled line filters. The filter has a wide passband with a 2:1 voltage standing-wave ratio bandwidth of around 10% and an insertion loss of 0.5 dB at 10 GHz. Simulated results agree very well with experimental results.

High-Q inductors and low-loss bandpass filters on Al2O3 substrates by thin-film technology

High-Q spiral inductors were designed and fabricated on high-resistivity Al2O3 substrates with an air-bridge technology. A maximum Q-value of 36 was achieved for a 2.74 nH inductor at 2.5– 5.5 GHz. Detailed broadband models for inductors and interdigital capacitors have been developed based on measured results, which enable us to build a low insertion loss 2.4 GHz bandpass filter with a size of 2 mm×2 mm. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 322–326, 1999.

Ka-band slot-fed higher order-mode low-loss Fabry-Perot filters

Low-loss bandpass filters consisting of Fabry-Perot resonators excited by slots which couple to higher order resonator modes are demonstrated. For close reflector spacings, the slots efficiently couple power from rectangular waveguide to the TEM/sub 400/ and TEM/sub 300/ modes of the resonator. At Ka-band the filters have insertion losses less than 1 dB in general and less than 0.5 dB in some cases. The unloaded Q values of the filters range from 1500 to 3000. The filters are mechanically tunable over a 25% bandwidth.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Slot-fed higher order mode Fabry-Perot filters

Low-loss bandpass filters consisting of Fabry-Perot resonators excited by waveguide-fed slots coupling to higher-order resonator modes are demonstrated. For close reflector spacings, the waveguide couples efficiently through the slots to the TEM/sub 400/ and TEM/sub 300/ modes. The characteristics of both rectangular and circular waveguide feeds with various slot lengths and widths are presented. At X-band the filters have unloaded Q values which range from 1000 to 7000 with insertion losses less than 1 dB. The filters which have the rectangular waveguide feeds are mechanically tunable over a 20% bandwidth. >

Development of a High-Q Multilayer Ceramic Resonator

It has been discovered that multilayer ceramic resonators, manufactured by a cofiring method at a temperature above the melting point of the inner conductor, have an improved Q-factor. The increase in Q-factor enabled the realization of an S-band multilayer low-loss bandpass filter (BPF). In this paper the insertion loss of the cofired BPFs is examined, and a relationship between firing temperature and Q-factor is established.

A low-loss bandpass filter using electrically coupled high-Q TM/sub 01 delta / dielectric rod resonators

For a TM/sub 01 delta / mode dielectric rod resonator placed coaxially in a TM/sub 01/ cutoff circular waveguide, characteristics such as the resonant frequency, its temperature coefficient, the unloaded Q, and the other resonances are discussed on the bases of accurate calculations using the mode-matching method. The results show that this resonator compares favorably with a conventional TE/sub 01 delta / mode dielectric resonator, particularly for realization of a high unloaded Q. Analytical results also verify that interresonator coupling between these two resonators can be expressed equivalently by a capacitively coupled LC resonant circuit. A four-stage Chebyshev filter having a ripple of 0.035 dB and an equiripple bandwidth of 27 MHz at a center frequency of 11.958 GHz was fabricated using these resonators. Its insertion loss is 0.5 dB, which corresponds to an unloaded Q of 17000, and no spurious response appears in the frequency range below 17 GHz. >

Some new approaches to improved low-loss SAW bandpass filters

In recent years several new forms of low-loss SAW bandpass filter have been devised which are suitable for mass production. The letter describes a variety of modifications to these basic configurations which can lead to superior performance in various important respects, including increased fractional bandwidth and greater stopband rejection.

New Application of Evanescent Mode Wave-Guide to Filter Design

Evanescent waveguide (rectangular or round) sections are used in conjunction with an admittance inverter synthesis technique incorporating frequency variable turns ratios to realize wide-band microwave (up to 1 octave) and low-frequency (60-MHz) low-loss bandpass filters. This work extends and corrects previous published information.

A hybrid ferrimagnetic-dielectric microwave filter

This paper describes a low-loss tunable dielectric resonator band bandpass filter for the frequency range 1 to 12 GHz. The filters are mechanically and/or magnetically tuned. Mode splitting, due to coupling between dimensional dielectric resonances with ferrimagnetic modes, and heat sinking techniques significantly improve the power-handling capabilities.