Quarter-wavelength Resonators Research Articles

Miniaturized ultra-narrowband HTS linear phase filter with CQ units sharing quarter-wavelength resonators

This paper proposes a method for designing a miniaturized ultra-narrowband high-temperature superconducting (HTS) linear phase filter based on the resonator-shared cascaded quadruplet (CQ) units constructed by the quarter-wavelength microstrip line. Two types of CQ unit with different coupling configurations are utilized to introduce transmission zeros and realize the linear phase. The introduction of transmission zeros increases the transition band roll-off rate, and the in-band group delay characteristic is improved through the phase compensation. The number of resonators and the filter size further decrease by sharing a resonator between two adjacent CQ units. Finally, a ten-order compact ultra-narrowband linear phase HTS filter with three CQ units is designed to demonstrate the feasibility. The central frequency of the filter is 450 MHz with the fractional bandwidth of 2.22%, and the dimension is 38.7 mm × 12.5 mm (0.141λ g0 × 0.047λ g0, λ g0 is the guided wavelength at the central frequency f 0). The measured results show an excellent performance in the insertion loss, the out-of-band rejection, the return loss, and the passband selectivity. Moreover, the bandwidth with a group delay ripple within 30 ns occupies 70% of the entire passband, highlighting the linear phase feature. In addition, the first parasitic passband is located at 3.8 times of the fundamental frequencies. The test results are in good agreement with the simulated ones.

Design of New Compact Multi-Layer Quint-Band Bandpass Filter

In this paper, we propose the new compact multilayer quint-passband bandpass filter. The multilayer substrate technique is used for further miniaturizing the circuit size. The filter has quint passband at 1.8, 2.5, 3.3, 3.8 and 4.5 GHz. Coupled resonators such as the stepped impedance resonators (SIRs), stub-loaded uniform impedance resonators (UIRs), and quarter-wavelength uniform impedance resonators are applied to produce the quint-passband of the filter simultaneously. The stub-loaded uniform impedance resonators and stepped impedance resonators can easily obtain a filter with closed passbands. Using a multilayer substrate technique, the filter can provide multipath propagation to improve the frequency response and achieve a compact circuit size. The proposed quint-passband bandpass filter shows a simple configuration, a practical design method, and a small circuit size.

Theoretical Study of the Frequency Multiplier Based on Irregular Quarter-Wavelength Microstrip Resonator with Thin Magnetic Film

The characteristics of a frequency doubler on a resonant microstrip structure with a thin magnetic film were studied theoretically. The electrodynamic calculation of the structure was performed within the quasi-static approximation. Nonlinear response of film magnetization was calculated taking into account the second-order terms in the Landau-Lifshitz equation. The frequency response of the microstrip resonator was calculated. It was shown that due to the use of the resonant circuit, high efficiency of the input signal energy conversion into the output signal at a doubled frequency was achieved. The optimal values of the magnitude and direction of an external static magnetic field, which ensure the maximum output power at a doubled frequency, were determined.

Accounting of the parasitic effects during measurement of the effective permittivity using the quarter-wavelength resonator method

The analysis, approximations and accounting of the influence of the main parasitic effects that affect the results of the measurement are provided in this paper. The method of dielectric constant measurement of coaxial connectors support beads is suggested. The comparison between the acquired results using the suggested method and the reference is made. The results suggest that the method can be used for dielectric constant measurement of the coaxial connector support beads with the accuracy comparable to the method of the volume resonator for rod samples H01p by GOST 8.623-2015.

Dual-Band and Wide Stopband Coaxial Filters Using Open-Circuited-Stub-Loaded Resonators

Novel open-circuited-stub-loaded coaxial resonator (OCSLR) is introduced in this brief. This resonator consists of a traditional coaxial resonator, which is vertically loaded by an open-circuited stub. Based on the resonant properties, the first two resonant frequencies can be flexible controlled by properly choosing the impedance ratio and length ratio. The proposed dual-band filter is achieved by employing OCSLRs which act as dual-mode resonator. The proposed wide stopband filter is realized by two OCSLRs loaded at different heights together with a traditional quarter-wavelength coaxial resonator, resulting in the same fundamental frequencies and different harmonic frequencies. Two design examples are manufactured to validate the concept. The measure results show good agreement with simulations.

Testing the quantization of electromagnetic field in a quarter-wavelength transmission line resonator by traveling-wave scattering measurements

A half-wavelength cavity, wherein the electromagnetic field is quantized as standing-wave photons, is a typical artificial quantum system that has widely been used to implement quantum information processing. In this paper, we propose an approach to confirm the quantization of the electromagnetic field in another type of cavity, namely, a quarter-wavelength transmission line resonator (TLR), by using traveling-photon scattering measurements. Furthermore, we show that the number of photons in a TLR can be destructively detected by using the usual IQ-mixed technique. We hope that quarter-wavelength TLRs may also serve as quantum devices to implement on-chip solid-state quantum information processing.

Cross Coupling of a Solid-State Qubit to an Input Signal due to Multiplexed Dispersive Readout

The integration, scale-up, and multiplexing arrays of superconducting qubits in quantum circuits are the main challenges of superconducting quantum technology. Here we experimentally investigate the solid-state qubit multiplexing readout scheme, containing coplanar quarter-wavelength resonators coupled with a planar Xmon-type qubit, connected to a common coplanar transmission line. We find that the qubit energy spectrum is modified in the presence of an additional exciting signal at the fundamental frequency of the neighboring resonators. We attribute the origin of this effect to the electromagnetic field propagating through the common ground plane, which changes the qubit's characteristics. Our finding may be useful for the development of scalable superconducting quantum integrated circuits with arrays of multiplexed or coupled qubits for applications in superconducting quantum processing and computing.

A 12-pole VHF band high selective high temperature superconducting filter

A 12-pole VHF band high temperature superconducting (HTS) filter with a spiral quarter-wavelength resonator is introduced. The coupling characteristics of the proposed resonator, cross structure and external quality factor is analyzed in detail. The HTS filter is fabricated on a 3-inch-diameter double-sided DyBa2Cu3O7 HTS thin film with a LAO substrate and measured with a low-temperature test system at 77 K. The measured filter has a center frequency of 119.93 MHz and a 1-dB passband of 10.04 dB. Due to the introduction of transmission zeros, the rectangular coefficient (BW60dB/BW1dB) of the measured filter is about 1.20, which shows excellent selectivity. The measured results are in good agreement with the simulated ones.

Design of a Compact SISL BPF With SEMCP for 5G Sub-6 GHz Bands

In this letter, a cross-coupled dual-bandpass filter (BPF) with separate electric and magnetic coupling paths (SEMCPs) for 5G sub-6 GHz applications is proposed. Source-to-load couplings are also introduced in this structure for the flexibility of heterogeneous feed lines. Five controllable transmission zeros (TZs) in total are produced in the dual-band filter. The filter achieves good overall performance by adopting two pairs of quarter-wavelength stepped-impedance resonators (SIRs). To minimize the size of the filter and enlarge the controllable range of the second passband, the SIRs forming the second passband are separated and folded onto two different layers. The measured dual band filter achieves fractional bandwidths of 7.82% and 4.08%, centered at frequencies of 3.45 and 4.9 GHz with insertion losses of 1.15 and 1.42 dB, respectively.

Design and Analysis of Dual-Band Implantable Antennas Based on Effective Relative Permittivity Calculation

This article presents the design and analysis of dual-band implantable antennas based on effective relative permittivity calculation. First, the effective relative permittivity for a microstrip antenna inside lossy tissue is analyzed, helping establish the basis for the design of our proposed dual-band implantable antenna. The antenna operates in 1.4 GHz Wireless Medical Telemetry Service (WMTS) band and 2.45 GHz industrial, scientific, and medical (ISM) band under proper feeding scheme. The lower band with quarter-wavelength resonance is realized by introducing two shorting pins to orthogonal strips. As a disturbance between two arc-shaped tails with open end is introduced, it can achieve circular polarization (CP) radiation property. Meanwhile, the higher band with half-wavelength resonance is realized through the path connecting two asymmetric open-end tails, so as to achieve linear polarization (LP) radiation property. As such, a wide CP bandwidth of 10.38% in WMTS band and a wide impedance bandwidth of 21.3% in ISM band are achieved and in final verified in experiment.

Point to point propagation over a phase gradient grooved surface

Previous work on deriving a modal theory for predicting point-to-point propagation over a uniformly grooved surface is extended to predict propagation over a periodic variable depth grooved surface with a low flow resistivity porous material of different thickness in each groove. The form of the surface is intended to create an approximately linear phase gradient for plane waves reflected from the surface. The resulting attenuation due to ground effect is found to be larger and more broadband than predicted over either an acoustically hard grooved surface or an acoustically soft layer with thickness equal to the largest groove depth for the same source-receiver geometry. Various contributions to the excess attenuation spectrum from surface waves associated with the different groove depths, quarter wavelength resonances in the grooves, the phase gradient for plane wave reflections and diffracted modes are investigated. As result the broadband nature of the excess attenuation is explained and important parameters in designing such surfaces are identified.

Nonlinear Quantum Processes in Superconducting Resonators Terminated by Neon-Focused-Ion-Beam-Fabricated Superconducting Nanowires

We have used a neon focused-ion-beam to fabricate both nanoscale Nb Dayem bridges and NbN phase-slip nanowires located at the short-circuited end of quarter-wavelength coplanar waveguide resonators. The Dayem bridge devices show flux-tunability and intrinsic quality factor exceeding 10,000 at 300 mK up to local fields of at least 60 mT. The NbN nanowires show signatures of incoherent quantum tunnelling of flux at 300 mK.

High Selectivity Slot-Coupled Bandpass Filter Using Discriminating Coupling and Source-Load Coupling

A multilayer bandpass filter with high selectivity is proposed in this letter. Discriminating coupling formed by slot-coupled quarter-wavelength and half-wavelength resonators introduces a zero at 3f0 (f0 is the center frequency) and the second harmonic is also suppressed due to the quarter-wavelength resonators. Owing to multilayer structure, source-load coupling is introduced to improve selectivity. Then an extra coupled line path is added with the same amplitude as the discriminating coupling path while they are out of phase. Thus signal cancellation produces three extra transmission zeros, with the selectivity and suppression performance further improved. To validate the design, a prototype bandpass filter centered at 2.49 GHz with 3 dB fractional bandwidth of 8.1% is fabricated. Both simulated and measured results are in good agreement and show good performance of the proposed bandpass filter.

Design and Fabrication of 3-D Printed Inline Coaxial Filters With Improved Stopband

This article presents a new class of filters, conceived for the fabrication with additive manufacturing technologies, with a wide stopband. The resonators are made of a coaxial line where supports are the coupling elements between them. The wide stopband is obtained using two different solutions. The first is the use of stepped-impedance resonators, whereas the second is the use of quarter wavelength resonators. Several prototypes have been built, and the experimental results show the validity of the solution.

Compact Spoof Surface Plasmon Polaritons Waveguide Integrated With Blind Vias and Its Applications

A novel compact spoof surface plasmon polaritons (SPPs) waveguide integrated with blind vias is proposed in this brief. Depending on the groove orientation, the SPP structure leads to asymmetrical electromagnetic (EM) field confinements in the transverse plane, where the EM field is strongly confined around the groove orientation but much weaker in the opposite side. Due to this strong field confinement, the measured crosstalk between two SPP waveguides with 1 mm edge separation is −25 dB in 3–13 GHz band, a reduction of 18 dB on average when compared with microstrip line implementation. Due to the weaker field confinement, energy from the SPP waveguide can be easily coupled into other parasite structures for filter designs. By loading quarter-wavelength SPP resonators along the main SPP waveguide, we can introduce notched frequencies in the transmission. The number of notches and their frequencies can be controlled by SPP dispersion.

Providential Tides: the Double Low Water of Narragansett Bay

We investigate a mechanism for producing double-lows and double-highs in the semi-diurnal tide by selective amplification of higher harmonics in a resonant gulf. A double low water is observed at Providence, RI, near the head of Narragansett Bay on days when there is a flattening of the low water tidal curve at Newport, at the mouth of the bay. The flattening is caused by an unusually large quarter-diurnal component to the tide at Newport. The quarter diurnal component has the right phase (a maximum close to the time of the minimum in the semi-diurnal tide) to produce a prolonged flattening of the tidal curve around low water. The natural period of Narragansett Bay (for quarter-wavelength resonance) is close to 4 h and the quarter diurnal tide is amplified, relative to the semi-diurnal tide, within the bay. The selective amplification of the higher harmonic further prolongs the flattening effect at Providence and, occasionally, is sufficient to create a double low water at the head of the bay from quarter and semi-diurnal tides alone. More often, though, a sixth-diurnal harmonic produced within the bay, added to the flattened low water at Providence, creates the double low water. This mechanism of selective amplification of tidal harmonics could be relevant to double tides elsewhere.

Development of Large Array of Kinetic Inductance Detectors Using Commercial-Class External Foundries

This study focuses on kinetic inductance detectors (KIDs) fabricated in external foundries using 6 and 8-inch processes. These processes allow us to fabricate large arrays of KIDs in a scalable manner. The support of such a wide variety of astronomical and particle-physics applications requires large numbers of superconducting detectors. For example, the sensitivity of the cosmic microwave background measurements has exponentially improved over the past few decades. The most significant advantage of KIDs is scalability to a large array due to the intrinsic frequency multiplexing scheme. The first step of fabricating a large array of KIDs is designing test chips to check the performance of the 6 and 8-inch micro-electro-mechanical system processes. The KIDs are made of a single pure aluminum film and consist of coplanar waveguide quarter wavelength resonators with a feedline. Each wafer is filled with 32 chips, where the chip size is 20 × 20 mm2, with 48 resonators on each chip. The chips are evaluated using a dilution refrigerator at temperatures ranging from 100 to 500 mK. The quality factor of the resonators, temperature dependency of the resonance frequency, and yields are comparable with those of the KIDs fabricated in a dedicated clean room for superconducting detectors.

Broadband microwave metamaterial absorber based on magnetic periodic elements

In this paper, we propose and demonstrate a broadband microwave absorber based on magnetic metamaterial structure elements. We deploy FeCo soft magnetic composite with droplet shape as the primary resonant element. By investigating the resonant modes and the coupling between periodic unit-cells and the incident microwave, it is found the intrinsic magnetic susceptibility of the magnetic elements could make the magnetic field confined in the magnetic element, and thus results in a broadband microwave absorption. Our work provides a new approach to realize broadband microwave absorbers based on hybrid absorption mechanisms, including dielectric resonator effect, one quarter wavelength resonance effect, and grating effect.

A Miniaturized Wideband Bandpass Filter Using Quarter-Wavelength Stepped-Impedance Resonators

In this paper, we present a simple method to design a miniaturized wideband bandpass filter with suppression of the third harmonic, using only two quarter-wavelength stepped-impedance resonators (SIRs). The resonant modes of the quarter-wavelength SIR, depending on the impedance ratio (K) and electrical length ratio (α), are discussed first. As to setting the resonant frequency of the SIR for the lower band edge of the required band, the size parameters of two quarter-wavelength SIRs can be determined by selecting the desired impedance ratio (K) and length ratio (α). By using the opposite directional arrangement of two SIRs with direct taped input/output ports, the wideband response can be formed. A filter example is shown in this study to address this simple design procedure. The measured results of the fabricated filter have a wide passband response from 3.3 to 5.8 GHz, with an insertion loss of 1.5 dB, a return loss of 20 dB, an extended bandwidth ration of 55%, a low-average group delay of less than 0.75 ns, and a stopband from 6 to 12 GHz, with an attenuation level of 20 dB. Due to the similar 0° feeding, a transmission zero at 8.3 GHz appears near the band edge; thus, improving the band selectivity. The proposed filter can have a very simple structure and a miniature size. Simulated results and measured results are in good agreement.

Coupling Matrix Representation of Nonreciprocal Filters Based on Time-Modulated Resonators

This paper addresses the analysis and design of non-reciprocal filters based on time modulated resonators. We analytically show that time modulating a resonator leads to a set of harmonic resonators composed of the unmodulated lumped elements plus a frequency invariant element that accounts for differences in the resonant frequencies. We then demonstrate that harmonic resonators of different order are coupled through non-reciprocal admittance inverters whereas harmonic resonators of the same order couple with the admittance inverter coming from the unmodulated filter network. This coupling topology provides useful insights to understand and quickly design non-reciprocal filters and permits their characterization using an asynchronously tuned coupled resonators network together with the coupling matrix formalism. Two designed filters, of orders three and four, are experimentally demonstrated using quarter wavelength resonators implemented in microstrip technology and terminated by a varactor on one side. The varactors are biased using coplanar waveguides integrated in the ground plane of the device. Measured results are found to be in good agreement with numerical results, validating the proposed theory.