Vladimir V. Tyurnev

DUAL-MODE SPLIT MICROSTRIP RESONATOR FOR COMPACT NARROWBAND BANDPASS FILTERS

A straight split dual-mode microstrip resonator is proposed. The frequencies of the two flrst oscillation modes in the resonator may be brought closer together by adjusting a split parameter whereas the frequency of the third mode remains approximately equal to the doubled average frequency of the flrst and the second modes. It is shown that formulas derived within 1D model give qualitatively true relations between the resonant frequencies and the structure parameters of the resonator. Examples of narrowband bandpass fllters of the fourth and the sixth order are described. Transmission zeros below and above the passband substantially improve the fllters performance. The simulated frequency response of the three-resonator dual-mode fllter is compared with the measured response of the fabricated fllter.

Highly Selective Suspended Stripline Dual-Mode Filter

Miniature bandpass fllter constructions based on a novel dual-mode suspended stripline resonator are proposed. Because of a special structure of the resonator, the frequencies of two flrst oscillation modes may be brought closer together. That allows realizing narrowband fllters with the wide upper stopband. The fllters have low insertion loss in the passband at small dimensions. Several transmission zeros substantially improve the fllter performance. The derived coupling coe-cients account for some features in the frequency response of the fllter. The second-order and fourth-order fllters with transmission zeros have been fabricated and measured.

Miniature Suspended-Substrate Bandpass Filter

A new quasi-lumped suspended-substrate stripline structure admitting implementation of miniature highly selective narrowband filters is studied. Appreciable improvement of the device selectivity is achieved with supplementary strip conductors introduced between the resonators, which induce attenuation poles near both passband edges. Furthermore, these supplementary conductors reducing the coupling between the resonators allow diminishing the interresonator spacing and the total size. A four-resonator filter is synthesized using the intelligence optimization method. Experimental results of the manufactured filter are presented. Received 6 July 2010, Accepted 11 August 2010, Scheduled 16 August 2010 Corresponding author: V. V. Tyurnev (tyurnev@iph.krasn.ru).

A microstrip diplexer based on dual-mode resonators

A miniature third-order microstrip diplexer comprising a traditional T-shaped dual-mode resonator at the input and one dual-mode resonator of original design, with regular strip conductors split from one end, at the output of each channel. The passband formation in each channel of the diplexer involves two resonances of the lowest modes of one split microstrip resonator and the resonance of one of the two modes of the T-shaped microstrip resonator. The proposed device is simple to manufacture and allows the central frequencies and bandwidths in each channel to be varied within broad limits. The good prospects of the proposed microstrip diplexer are confirmed by the high characteristics of its working prototype.

Miniature bandpass microwave filter with interference suppression by more than 100 dB in a wide rejection band

A new planar resonator design in which a single conductor is replaced by three parallel stripe conductors located one above the other on a suspended two-layer substrate is proposed. It is shown that the resonator longitudinal sizes can be significantly reduced and, at the same time, the resonator intrinsic Q factor and frequencies of higher oscillation modes can be increased. A fourth-order bandpass filter with a central frequency of the transmission band (relative width 5%) of 1 GHz has been developed and fabricated. This filter has a −100-dB rejection band up to frequencies exceeding 10 GHz. The filter is enclosed in a metallic case with an internal size of 38 × 12 × 7.5 mm. It is shown that a similar filter fabricated in accordance with low-temperature cofired ceramic (LTCC) technology has a −40-dB rejection band up to 30 GHz, with sizes reduced to 5.0 × 4.25 × 1.24 mm.

SYNTHESIS AND INVESTIGATION OF THREE- SECTION MICROSTRIP FILTER ON FOLDED DUAL-MODE STEPPED-IMPEDANCE RESONATORS

A new structure of an ultra-wide bandpass fllter is considered. An intelligence method of optimization is applied flrst for synthesis of three-section fllter on dual-mode resonators. An area of fractional bandwidth values and values of dielectric constant of the substrate, where synthesis problem for the fllter has a solution, is determined theoretically. Experimental results show good agreement with simulated values.

A miniature dual-band filter based on microstrip dual-mode resonators

A microstrip dual-band bandpass filter (DBF) with an original miniature design is described. The filter consists of thee microstrip dual-mode resonators, which are rendered dual-mode by splitting their regular strip conductors from one end by longitudinal slots. The formation of one passband of the DBF involves the resonances of even modes of each microstrip double-mode resonator, while the other passband is formed by the resonances of odd modes. The proposed device is simple to manufacture and allows the central frequencies and widths of each passband to be tuned within broad limits. A method of DBF tuning has been developed. Good prospects of the proposed microstrip DBF are confirmed by the high characteristics of its working prototype.