Dual-mode Cavity Research Articles

Design and Development of Advanced Cavity-Based Dual-Mode Filters Using Low-Temperature Co-Fired Ceramic Technology for $V$-Band Gigabit Wireless Systems

In this paper, a novel concept of 3-D integrated -band dual-mode cavity filters, which permit the realization of a variety of quasi-elliptic responses by creating transmission zeros, has been demonstrated using multilayer low-temperature co-fired ceramic (LTCC) technology. A single-cavity resonator is designed to generate a degenerate resonance of two orthogonal modes ( and ), enabling dual-mode operation. The appearance and elimination of transmission zeros have been analyzed through the multipath coupling diagrams and lumped-element models. The quasi-elliptic dual-mode filters with the appropriate locations of the transmission zeros are then developed for receiver and transmitter channels of a -band transceiver module. Two pre-synthesized, dual-mode cavity filters are vertically stacked with two types of inter-coupling slots (1: rectangular, 2: cross) to realize the multipole filters for 60-GHz wireless local area network narrowband applications. These proposed filters are the first to be reported and have great potential to be integrated into miniaturized -band LTCC transceiver modules.

Design of dual-mode bandpass waveguide elliptic filters for simple fabrication by milling

New dual-mode bandpass waveguide elliptic filters with the added advantage of easy fabrication by milling are introduced. The filters have an in-line configuration in which the dual-mode cavities are kept homogeneous with no intracavity coupling elements. Coupling between adjacent cavities is implemented by rectangular irises, which are placed at the center top of the cross section. The structure can be fabricated as a single piece which is completed by a metallic cover plate. Example filters are designed to show the performance of this class of dual-mode filters. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.

Synthesis and design of asymmetrical dual-band bandpass filters based on equivalent network simplification

Although the synthesis of symmetrical dual-band bandpass filters has been studied, little seems to be known about the general asymmetrical case. In this paper, a procedure for the synthesis of general asymmetrical dual-band bandpass filters implemented with inline dual-mode cavities is proposed. The inline architecture, as well as the asymmetrical nature of the response, lead naturally to the choice of an extended box topology or generalizations of the latter. It was recently shown that these topologies possess the property of multiple solutions, meaning that the related coupling matrix synthesis problem admits several solutions. On one hand, this multiplicity offers some flexibility to the designer, but on the other hand, working with multiple solutions may lead to ambiguities during the tuning process. Our procedure takes the best of both worlds: using the list of equivalent coupling matrices, simplifications of the original topology can be obtained by canceling some particular couplings. The locations of cancelled couplings are chosen so as to preserve the electrical response and to provide some hardware simplifications. It is also shown that the resulting simplified topology no longer has the multiple solution property, therefore solving ambiguity problems. The procedure is detailed and demonstrated on two examples.

Symmetric dual-mode filter based on substrate integrated waveguide (SIW)

A planar four-pole dual-mode filter with symmetric transmission response based on substrate integrated waveguide (SIW) is proposed. The filter centered at 10 GHz, consisting of two TE102–TE201 dual-mode SIW cavities, is implemented in a single layer substrate by PCB process. A linear microstrip taper is used to implement the transition between 50 Ω microstrip and SIW. The measured results are in agreement with simulated results.

Substrate integrated waveguide (SIW) asymmetric dual-mode filter and diplexer

Substrate integrated waveguide (SIW) can be used to implement high Q waveguide components with the same easy and low-cost fabrication process as planar circuits. In this paper two inline three-pole dual-mode filters with asymmetric transmission response based on SIW are presented. These two filters, consisting of a TE102-TE301 dual-mode SIW cavity and a TE101 mode SIW cavity, are centred at around 10 GHz with a transmission zero on the left of the passband and the right of the passband, respectively. Based on the two kinds of three-pole deal-mode filters, a diplexer with isolation better than 35 dB is developed. A linear microstrip taper is used to implement the transition between microstrip and SIW. The measured results agree with simulated results.

A beat-frequency tunable dual-mode fiber-Bragg-grating external-cavity laser

A dual-mode external cavity laser employing two spatially separated fiber Bragg gratings has been investigated. We experimentally demonstrated that, without utilizing polarization separation techniques, a closely spaced (/spl sim/0.3 nm) dual-mode emission can be stabilized if a specific in-phase relation between the external feedbacks and the gain chip facet residual feedback is satisfied at both lasing wavelengths. The radio-frequency (RF) beat signal generated by the dual-mode optical signal had a typical extinction ratio of 25 dB above the noise floor and a 3-dB linewidth of approximately 2 MHz. The RF beat signal had a frequency tuning range of 200 MHz, where the dual-single-mode spectrum can be maintained.

New in-line dual- and triple-mode cavity filters with nonresonating nodes

This paper presents new in-line pseudoelliptic bandpass filters with nonresonating nodes. Microwave bandpass filters based on dual- and triple-mode cavities are introduced. In each case, the transmission zeros (TZs) are individually generated and controlled by dedicated resonators. Dual- and triple-mode cavities are kept homogeneous and contain no coupling or tuning elements. A third-order filter with a TZ extracted at its center is designed by cascading two dual-mode cavities. A direct design technique of this filter is introduced and shown to produce accurate initial designs for narrow-band cases. A six-pole filter is designed by cascading two triple-mode cavities. Measured results are presented to demonstrate the validity of this novel approach.

A new probe‐excited dual‐mode cavity filter

AbstractThis paper presents a novel configuration for dual‐mode cylindrical cavity filters operating in the TE111 mode. The proposed configuration is compact yet simple, with only one coupling probe to excite two orthogonal TE111 modes in a cylindrical waveguide cavity. A prototype is designed to operate at 10 GHz. Simulated and experimental results are provided. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 335–337, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11053

CAD applying the finite-element method for dielectric-resonator filters

The progress of numerical techniques now permit us to analyze rigorously complex devices such as dual-mode cavity multipole filters or planar passive elements for coplanar monolithic microwave integrated circuits (MMICs). In this paper, we describe a rigorous design of dielectric resonator (DR) filters applying the finite-element method (FEM). We first present a dual mode coupling technique which replaces classical DRs, coupling, and tuning screws, which are commonly used in dual-mode filters, by slotted DRs. Next, a new theoretical analysis based on the contribution to the dual-mode filter response of the first DR hybrid mode and of higher order modes is described. This analysis can be applied to any type of microwave dual-mode filter. It allows us to define a procedure which explains the presence and controls the position of the two transmission zeros in the filter responses. In this paper, this procedure has been applied to improve filtering performances of a dual-mode DR filter. Finally, a synthesis method is developed to rigorously design for the first time, a four- and an eight-pole slotted DR elliptic filters. The experimental results were obtained with no tuning and the theoretical ones show good agreement.

Miniaturized HTS/dielectric multilayer filters for satellite communications

Presently, most communication satellites contain well over a hundred of filters in their payload. Typical satellite multiplexers use dual mode cavity or dielectric resonator filters which are large and heavy. As future advanced electronic systems for satellite communications become more complex, they will need even more filters requiring filter miniaturization without performance degradation. Therefore, any improvement in filter technology consistent with this requirement could enhance satellite's performance. To reduce the size, weight, and cost of the multiplexers without compromising performance, we introduce a new class of dual mode multilayer filters consisting of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// and LaAlO/sub 3/ thin films. The multilayer configuration in C-band, for example, occupies only 1% of the volume of its dielectric resonator counterpart. Details of the design, fabrication, and testing of these filters will be presented.

Correction To "The Relationship Between Dual Mode Cavity Cross-coupling And Waveguide Polarizers"

Correction To "The Relationship Between Dual Mode Cavity Cross-coupling And Waveguide Polarizers"

The relationship between dual mode cavity cross-coupling and waveguide polarizers

Cross-coupling in dual-mode cavity filters may be obtained by introducing an asymmetry within the cavity cross section at an angle of 45/spl deg/ to the two orthogonal modes. This paper presents a novel formula relating the resulting cross coupling coefficient between the orthogonal resonances to the polarization of a waveguide polarizer. Previous theories for such polarizers may then be applied directly to the dual mode filter situation. Formulas enabling the dimensions of the asymmetries for required coupling coefficients are presented for square and circular waveguide cross sections.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A new rigorous method for the determination of iris dimensions in dual-mode cavity filters

A variational method based on the mode expansion is used in order to determine the accurate physical dimensions of coupling irises in dual-mode cavity filters. By considering the concept of localized and accessible modes, a series of convergence tests are carried out in order to optimize the number and nature of modes which should be included in the numerical calculations. As a consequence, the size of matrices involved and the corresponding computation time are reduced dramatically. This approach, validated by corresponding experimental data, allows us to achieve a considerable reduction of the fabrication time of this type of filter. Actually, the filter can be tuned immediately without any correction of the calculated irises.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Filter design using in-line triple-mode cavities and novel iris couplings

The authors present principles for triple-mode filter designs based on a sidewall-tuned triple-mode cavity and two iris geometries. It is shown that these principles allow optimal filter realizations with a minimum number of triple- and dual-mode cavities. Verification of these principles is obtained by realizing several filter types. Experimental results are provided for elliptic-function filters of fifth, sixth (both in in-line configuration), and seventh order. >

A circuit model of probes in dual-mode cavities

An accurate model of coaxial probes used as input and output ports in dual-mode cavities (either air-filled or dielectric-loaded) is presented. The model precisely predicts such empirically observed phenomena as limited out-of-band isolation, generation of extra transmission zeros, and asymmetric responses. The model parameters can be determined from simple measured data. It is shown how the model can be used in the analysis and synthesis of canonical dual-mode filters. Experimental verification of the model for several configurations showed excellent agreement with theory. >

Synthesis and Realization of Narrow-Band Canonical Microwave Bandpass Filters Exhibiting Linear Phase and Transmission Zeros

The present study is concerned with the synthesis and realization of narrow-band canonical microwave bandpass filters exhibiting additional couplings between nonsuccessive resonant circuits. These bypass couplings effect, on the one hand, attenuation poles at finite frequencies and, on the other hand, make the bandpass filter nonminimum-phase, and therefore offer degrees of freedom for group delay equalization in the passband. The realization of canonical network structures with bypass couplings is possible by extracting from the chain matrix an ideal transformer, the input of which is connected, for example, in shunt with and its output in series with the remainder two-port. The extraction is associated with the reduction by 2 of the degree of the denominator polynomial of the chain matrix elements. To realize a clear correlation between the bypass elements and the electrical performance, canonical structures with sections that are bypassed only once or twice are proposed. Theoretical and measured curves of the examples of realization for 1235 MHz, consisting of coaxial cavities, and for 4000 MHz, consisting of dual-mode cavities, are seen to be in close agreement.

Dispersion studies of the 22 GHz water vapor line shape: I. The Lorentzian behavior

The line shape of the self-broadened rotational (5 −1 → 6 −5) transition of water vapor at v 0 = 22.235 GHz has been investigated on the basis of resonance dispersion information. Detailed information on absolute intensity, width, shift, and wing response was obtained without molecular effect modulation. A differential refractometer with one dual-mode cavity sensor was operated in the pressure range 5 × 10 −4 to 20 torr at 27°C. The dispersion was measured at fixed frequencies ( v 0±250 MHz) with slowly varying vapor pressure. In this first part of the study the results obtained for pressures above 0.1 torr are presented. For pressures higher than 2 torr, a Lorentzian line shape was confirmed with a constant maximum dispersion of ±0.387 × 10 −6. Down to 0.1 torr, the line center displayed Lorentzian behavior with the pressure-linear width of 17.99 MHz/torr and a violet shift of 1.38 MHz/torr, but the wing dispersion dropped more rapidly with decreasing pressure while the maximum dispersion increased. The Lorentzian line strength was determined and found to be in good agreement with the theoretical value as determined by the transition probability for the asymmetric rotor. The experimental strength yielded a maximum linear power absorption coefficient of 7.21 × 10 −6 cm −1.

Single-Mode Cavity Maser at 2200 Mc (Correspondence)

Cavity masers which have been reported in the literature have utilized a dual-mode cavity resonant at the pump and signal fre-quencies, but Strandberg, et al., has reported an X-band cavity maser which can be operated with the cavity resonant only at the signal frequency. Siegmann has also reported a multiplicity of resonances in his cavity maser for the pump signal which might possibly be caused by some sort of dielectric loading effect.