Post dielectric resonator at the junction of three rectangular waveguides: calculations and measurements

A low-profile dual-polarized metasurface antenna with high isolation and low cross-polarization is proposed in this communication. The proposed metasurface consists of an array of 4×4 patches. Through characteristic mode analysis (CMA), a pair of degenerate modes is identified to achieve the desired radiation features. By modifying the patches of the metasurface, the strongest mode current distributions of the two modes are moved from the center to the edge of the metasurface. One feed port can efficiently excite only one particular mode, and the other mode cannot be excited simultaneously. Each of the modes are differentially fed using two Y-shaped microstrip lines via two slots. As a result, both high isolation and low cross-polarization can be obtained. The simulation and experimental results show that the proposed antenna achieves not only a low profile of 0.05λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free-space wavelength at the center resonant frequency) but also a broad impedance bandwidth of 36% and a high isolation of 53 dB. In particular, the enhanced cross-polarization discrimination (XPD) is lower than -40 dB at the broadside, lower than -33 dB within ±30° of the main lobe, and lower than -28 dB within ±60° of the main lobe.

&lt;sec&gt; The topologically protected edge states of elastic waves in phononic crystal plates have the outstanding characteristics in wave manipulation such as the strong suppression of back-scattering and defect immunity, which can be used for controlling vibration and noise, detecting the structural damage, conducting the material nondestructive test and other engineering practices, and therefore have received much attention. But for plate structures, the propagation of elastic waves is complicated due to the coexistence and coupling of different types of wave modes, resulting in a challenge in designing topologically protected states. &lt;/sec&gt;&lt;sec&gt;In this paper, a simple phononic crystal plate with triangular holes is designed for elastic wave manipulation based on topologically protected edge states. The band structure characteristics of the unit cell are studied by varying the rotation angle &lt;i&gt;θ&lt;/i&gt; of the triangular holes around their geometric centers from the initial positions. It is found that the band structure of the initial unit cell with rotation angle &lt;i&gt;θ&lt;/i&gt; = 0° has two pairs of degenerate modes. At &lt;inline-formula&gt;&lt;tex-math id="M6"&gt;\begin{document}$ \theta = \pm 33^\circ $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20200542_M6.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20200542_M6.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;, a double Dirac cone appears at the center &lt;i&gt;Γ&lt;/i&gt; point of the Brillouin zone without requiring the lattices to fold, and a band inversion occurs on both sides of &lt;inline-formula&gt;&lt;tex-math id="M7"&gt;\begin{document}$ \pm 33^\circ $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20200542_M7.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20200542_M7.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; which can be characterized as a topological phase transition. &lt;/sec&gt;&lt;sec&gt;The elastic band gap and two kinds of pseudospin states with clockwise or counterclockwise circulating mechanical energy flux patterns in the band structure are found by calculating the projected band structures of a supercell which is composed of phononic crystals with different topological phases. Based on this finding, different constructions of phononic waveguide are used for implementing the numerical analysis to demonstrate the back-scattering immunity of the edge states when disorder, tortuosity and cavity are introduced into the waveguide. Unidirectional robust propagation and multichannel waveguide switch due to the pseudospin-dependent one-way edge modes are also validated with numerical models. The phononic crystal plate presented in this paper provides a simple realizable method of designing the topologically protected elastic edge states. &lt;/sec&gt;

In this letter, a compact dual-band dual-mode substrate integrated waveguide (SIW) balanced band-pass filter (BPF) with intrinsic common-mode (CM) suppression is designed by using a single perturbed SIW circular cavity. The vias and slot perturbations are introduced to tune the resonant modes TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">010</sub> , TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">110</sub> (a pair of degenerate modes), and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">210</sub> of a circular cavity. Thus, they can be used to form two differential-mode (DM) passbands with independently adjustable center frequencies and bandwidths. The SIW can be seen as a natural balun with intrinsic CM suppression. Furthermore, the planar differential excitation structure is designed to excite the perturbed SIW cavity. The CM noise cannot excite SIW cavity due to the characteristics of hybrid electromagnetic boundary. Finally, a compact dual-band dual-mode SIW balanced BPF at 8 and 10 GHz is designed and fabricated, and the measured results show good agreement with the simulated ones.

In this letter, the designs of narrow-band filters using two doublets of orthogonal modes in a quadruple-mode cavity resonator are presented. By properly arranging the frequency locations of these quadruple modes, namely TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub>/TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">101</sub>/TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">120</sub>/TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">210</sub>, single-band or dual-band performance can be realized. Since a pair of degenerate modes can be regarded as a doublet producing one transmission zero (TZ), two TZs are generated beside the passband because of two pairs of doublets (fundamental and high-order modes) in a single cavity resonator. A high-order filtering response is also explored by mounting a quarter-wavelength waveguide section nonresonating nodes (NRNs) between the cascaded cavity resonators. To verify the design methodology, an eighth-order single-band filter (at 11.0 GHz) and a fourth-order dual-band filter (at 11.1 and 12.6 GHz) have been simulated, fabricated, and tested. A good agreement between measurement and simulation is achieved.

In this letter, a pin‐loaded triple‐mode square patch resonator is proposed for bandpass filter (BPF) design. By loading short‐circuited pins underneath the patch, the patch resonator not only enables DC‐blocking, but also brings out one additional resonant mode, thus a triple‐mode patch resonator can be formed up under operation with a pair of degenerate modes. According to the field distributions, these three resonant modes can be tuned by virtue of loaded slots and pins, while these two degenerate modes can be properly split by offset‐positioning the two sets of pins. In final, a pin‐loaded triple‐mode patch BPF is designed, fabricated and measured to validate the predicted results.

In this article, a dual-mode dielectric waveguide resonator (DWR) is proposed. A dual-band bandpass filter (BPF) is fabricated using this DWR. The two passbands are constructed by a pair of higher-order modes. These higher-order modes are the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{TM}_{210}$</tex> mode and the TM120 mode, which are all from the rectangular dielectric waveguide resonator. Therefore, by changing the width of the resonator cw and the length of the resonator cl, the resonant frequencies of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{TM}_{210}$</tex> mode and the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{TM}_{120}$</tex> mode are able to be changed independently. The center frequencies of the filter can be adjusted freely. To excite and extract the modes, metallized blind holes can be set where their electric-fields are the strongest. In this way, the two modes do not affect each other. The coupling structures for different modes are realized by connecting corresponding metallized blind holes. By changing the depth of metallized blind holes at different positions on the resonator, therefore, the coupling coefficients of the two passbands are able to be under control freely so as to adjust the bandwidths of the two passbands independently. At last, the designed BPF's frequencies and bandwidths are able to be controlled freely.

The coupling coefficients between open dielectric resonators in three useful dielectric-filter configurations, calculated from an electric rather than from a magnetic excitation of the fields, are given. The limitations of the latter method are pointed out and experimental results are given which supports the first method and shows that the differences cannot always be neglected.

quency in the range of the first, second, and third harmonic components of the signal. It is of the greatest interest to measure the relationship to frequency of the readings of a wattmeter with a complex structure of the sensing elements of its input transducer, when the computation of its sensitivity is very difficult. Therefore, we selected as objects of our investigation a waveguide multielement bolometric wattmeter [i], a wattmeter based on a multielement directional coupler with a thermistor head, and a double-element ponderomotive wattmeter [2]. The bolometric transducer consists of a rectangular waveguide section with butt-end flanges. The waveguide carries inside it perpendicularly to its wide wall 16 tungsten-wire bolometers whose length coincides with the waveguide height. The two bolometer rows are located along the waveguide axis. The uhf signal power is measured by means of the substitution method with an automatic bolometric bridge. The directional coupler of the thermistor wattmeter consists of two parallel rectangular waveguides with a common wide wall, with 16 identical holes located in two rows along the waveguide axis serving as coupling elements. The transition loss of a hole amounts, in the waveguide frequency range, to ~40 dB with a directivity exceeding 40 dB. A waveguide thermistor head is connected to the lateral arm of the directional coupler. The uhf power is also measured by means of the substitution method. The waveguide ponderomotive wattmeter consists of a rectangular waveguide with two sensing elements in the shape of rings at an angle of 45 ~ to the waveguide axis and a system for indicating the rotation angle of both ring suspensions. The ring centers are located at a distance of equal to one-fourth the working wavelength along the waveguide axis. The wattmeter scale used for indicating the suspension deflections is calibrated in watts by means of the method described in [2]. The frequency as well as the dynamic ranges of the wattmeters were chosen to be similar for comparison purposes. Thus, the working frequency ranges of the bolometric wattmeter amounts to 3.94-4.85 and 4.85-6.64 GHz, of the wattmeter with the directional coupler to 3.94-5.64 GHz, and of the ponderomotive wattmeter to 4.75-5.25 GHz. The dynamic range of the bolometric wattmeter amounts to 0.3-10 W, of the wattmeter with the directional coupler to 0.1-50 W, and of the ponderomotive wattmeter to 1-20 W. The input transducers of all the wattmeters have waveguide cross sections amounting to 48  24 mm. The frequency characteristic of each wattmeter was repeatedly measured in the working range in the course of their calibration and periodic testing, and it was found that the measured data is in good agreement with the computation results. In addition to the basic wave type H1o others arise in the waveguide with a rising frequency, therefore, their fre

Rectangular waveguide slot arrays are commonly used in several microwave antenna systems. The slots are most often located in the broad wall of the rectangular waveguide, arranged longitudinally parallel with the waveguide axis, because this provides good control of the excitation of each slot over a large dynamic range by adjusting the offset of the slot from the center line of the waveguide. However, longitudinal slots can only radiate electrical fields that are transversely polarized with respect to the waveguide axis. If longitudinal (or dual) polarization is required, the slots (or half of them) must be located transverse to the waveguide axis. Transverse resonant slots in the broad wall are too strongly excited for use in large arrays, so transverse narrow slots in the narrow wall are preferred. In the latter case the slots are not excited unless they are tilted or coupled to tilted parasitic elements like wires or posts inside the waveguide. The purpose of the present paper is to analyse an untilted narrow wall slot excited by two tilted wires. An improved and extended analysis in which the slot extensions into the neighboring two broad walls are included, is described. The virtual cylinder method is applied to the calculation of the external admittances of the slot using wedge dyadic Green's functions and entire-domain basis functions in order to get good convergence of the integrals of the spectral domain formulations.

The hemispherical open resonator feeding by the rectangular waveguide was analyzed by using the modal analysis method. The open resonator was excited by the rectangular waveguide through a narrow slot, with a complete analysis of all the relevant modes in the waveguide and the open resonator, the coupling coefficients according to the difference width slots were derived among Ka waveband, further more, the coupling coefficients of a slot at different eigen frequency were calculated and were compared to experimental results.

This paper presents the research, design, and implementation of a low phase-noise dielectric resonator oscillator (DRO) operating at 9.4 GHz for X-band radar applications. A high-quality-factor dielectric resonator operating in the mode was employed to enhance frequency stability and suppress phase noise. The oscillator was realized using a microstrip coupling structure, with a GaAs FET transistor serving as the active element in the feedback network. Comprehensive electromagnetic and circuit-level simulations were conducted in CST and ADS to optimize the resonator coupling and feedback configuration, ensuring stable oscillation and effectively mitigating spurious modes. Compared with conventional oscillator designs, the proposed DRO demonstrates superior frequency stability and reduced phase noise, while maintaining a compact form factor. These characteristics render the proposed design highly suitable for modern X-band radar front-ends as well as other advanced microwave communication systems requiring low-noise and high-stability local oscillators.

A method for investigating the electromagnetic properties of high-Tc superconductors (HTS) in a 2-mm wavelength band has been proposed. The method is based on the use of a cylindrical tube open dielectric resonator (ODR) loaded with a HTS sample. The Josephson harmonic generation at microwave frequencies can be investigated by means of the method. A small cross section of the ODR makes it possible to investigate surface variations of HTS sample electromagnetic properties and their temperature dependencies.

During the last time open dielectric resonators (DR) excited on whispering-gallery type waves due to their high Q-factor on the higher modes are used to investigate the dielectric properties of not only solid substances but also of liquids. For these purposes in the first experiments DR (which was used as measuring cell) being immersed directly in tested liquid. The investigated liquid influenced on external caustic of DR that led to frequency sift and changes of resonator Q factor. New achievement in creation of the dielectrometer measuring cells have appeared after the creation of the resonant structures in which certain geometrical parts of resonators are used. At first, such DR were created with metal mirrors. The subsequent researches [1] have shown that oscillations exist also without a mirror, which itself leads to condensate of a spectrum and reduction of the quality of resonator.

IEEE Technical Field Awards are bestowed for contributions and leadership in specific fields of interest to the IEEE. Each year, the most prestigious honors are awarded to individuals whose exceptional achievements and outstanding contributions have made a lasting impact on technology, society, and the engineering profession <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . Following a 60-year career span in microwave engineering, starting with his 1963 undergraduate project, “Abrupt Transitions in Rectangular Waveguides,” the 2023 IEEE Electromagnetics Award goes to John Bandler, professor emeritus at McMaster University, Hamilton, ON, Canada, “for contributions to electromagnetic optimization and the modeling of high-frequency structures, circuits, and devices.”

A novel probe for high-T/sub c/ superconductor measurements based on the post dielectric resonator is described. Advantages of the device and the method of measurements include high sensitivity, simplicity, ability to measure small superconductor samples, and nondestructive measurements of selected areas of larger samples including thin-film superconductors. The technique and selected results are presented. >