Mixed Electromagnetic Coupling Research Articles

Compact and Wide-Stopband Bandpass Filter Using Hybrid Shielded EMCSIW and CSRR Resonators with a Mixed Electromagnetic Coupling Scheme

This paper presents a bandpass filter (BPF) exploiting hybrid shielded eighth-mode circular substrate-integrated waveguide (SD-EMCSIW) and complementary split ring resonator (CSRR) resonators. The proposed BPF leverages the SD-EMCSIW resonator with a 45-degree angle to create a second-order BPF with a mixed electromagnetic coupling scheme. Detailed analyses of the related electromagnetic characteristics and operating mechanisms have been performed. In order to further reduce the occupied area, the CSRR structures are embedded into the SD-EMCSIW resonators. Meanwhile, extra metallic via-holes are implemented to enhance the upper-stopband performance. A transmission zero (TZ) of the second-order BPF can be placed on either the left or right side of the passband and can be flexibly adjusted. To validate the design concept, a second-order hybrid SD-EMCSIW and CSRR BPF was designed, simulated, fabricated, and measured as a specific example. The prototype operates at a center frequency f0 of 8.3 GHz with a 3 dB fractional bandwidth of 8.1%. Two transmission zeros are located near the right passband. The upper-stopband rejection reaches up to 15 dB at 2.85 times the center frequency f0. Both the simulated and measured results show satisfactory agreement. Meanwhile, the overall size of the proposed hybrid SD-EMCSIW and CSRR BPF is 13.5 mm × 13.0 mm (0.37λ0 × 0.36λ0), featuring a compact physical dimension in the filter design.

Cavity filter with mixed electromagnetic coupling

Cavity filter with mixed electromagnetic coupling

Design of a Bandpass Filter with Mixed Electromagnetic Coupling Paths Using Vertical Split-Ring Resonators

We propose bandpass filters (BPFs) with mixed electromagnetic coupling paths (MEMCPs) that comprise two coupled vertical split-ring resonators (VSRRs) and present the equivalent circuit models of the coupled VSRRs. We demonstrate that the dominant coupling modes for the top and bottom layers of the VSRRs are magnetic (M) and electric (E), respectively, and that M-dominant coupling is required for high-selectivity BPFs. BPFs with narrow and wide bandwidths were designed based on the generalized coupling matrix. The proposed BPFs were fabricated and measured, and it is verified that the proposed BPFs have high selectivity due to the transmission zeros and a small circuit footprint due to the vertical structure of resonators. The fabricated narrow- and wide-band BPFs have the fractional bandwidths of 3.62% and 5.81%, respectively, with the overall size of 0.29 λ g × 0.043 λ g .

Compact Dual-Band Filtenna With Controllable Radiation Nulls for Vehicle Application

This paper presents a compact dual-band filtenna with controllable radiation nulls for Shark-Fin scenarios. The proposed filtenna is composed of three quarter-wavelength dual-band resonators. The resonator in the middle is fed by the probe. The other resonators on both sides of the middle resonator are coupled by the mixed electromagnetic (EM) field. Since the electric and magnetic couplings can be cancelled, the mixed EM coupling can be used to obtain more radiation nulls with less order than the other coupling mechanisms. Thus, the proposed antenna is straightforward and compact. Furthermore, the dual-band Quasi-elliptical responses are realized. Four radiation nulls are realized on both sides of two pass-bands, and the positions can be flexibly adjusted in dual bands. Without extra filtering circuits, high radiation efficiency can be achieved. To analyze and guide antenna design, the RLC equivalent circuit and extraction method are provided. For demonstration, the proposed filtenna is implement-ed. Radiation efficiency is about 64% and 83% within 2.4-2.5 GHz and 5.0-5.88 GHz, respectively. Moreover, the out-of-band supp-ression is over 20 dB. Compared with the traditional antenna, the in-band radiation performance of the proposed antenna is almost maintained, whereas out-of-band suppression is significantly enhanced. The proposed filtenna is suitable for Shark-Fin scenar-ios where multiple antennas operating at different frequency bands coexist. The interference from antennas at adjacent bands is reduced significantly due to the out-of-band suppression. Specially, the isolation between the proposed dual-band filtenna and antennas operating at the other bands can be improved by about 21dB.

High-Selectivity Bandpass Filter with Controllable Attenuation Based on Graphene Nanoplates.

A high-selectivity band pass filter with controllable attenuation based on graphene nanoplates is proposed in this paper. Graphene with controllable resistance has a good uniform attenuation effect to electric field intensity. The filter utilizes quarter wavelength stepped impedance resonators and mixed electromagnetic coupling to have compact circuits and high performance. The graphene nanoplates are loaded on the microstrip resonator to reduce the electric field intensity, which results in a flat attenuation in the passband. In addition, the filter has two transmission zeros, which lead to a strong selectivity. Finally, a high-selectivity bandpass filter with controllable attenuation is formed. By changing the bias voltage of graphene, a controllable attenuation of 1.64–11.13 dB can be achieved in the working passband centered at 1.36 GHz. In order to validate the concept, the prototype is fabricated and measured. The measurement results are in good agreement with the simulation results. The proposed high-selectivity bandpass filter with controllable attenuation based on graphene nanoplates has widely potential in reconfigurable wireless communication systems and radar systems due to its high integration and versatility.

Compact balanced diplexer based on hairpin split ring resonators with high isolation performance

In this paper, a compact balanced diplexer using a novel hairpin split ring resonator (H-SRR) is presented and demonstrated. First, the working principle of the proposed H-SRR is described, which shows a negative permittivity or a negative permeability in the stopband. It can be used to construct compact passive components and improve the stopband rejection performance. Then, the differential-mode (DM) excitation and common-mode (CM) excitation are investigated, respectively. Under DM operation, the H-SRR can provide one DM resonant mode. Under CM operation, the H-SRR can excite two CM resonant modes far from the DM resonant mode, thus producing a desired CM rejection performance. Moreover, by introducing a mixed electromagnetic coupling, transmission zeros are produced, significantly improving the DM isolation between the two channels. Finally, a balanced diplexer is designed and fabricated. The lower and higher channels of the diplexer are centered at 3.36 and 4.00 GHz. The DM channel isolation is better than 40/41 dB in the two passbands when the frequency ratio is less than 1.2, which is in satisfactory agreement with the simulated results.

RF Co-Designed Bandpass Filter/Circulator With Tunable Center Frequency, Bandwidth, and Out-of-Band Isolation

This letter reports on a new type of miniaturized RF co-designed bandpass filter/circulator (BPFC). Miniaturization is achieved by: 1) capacitively loading a multi-mode ferrite-based disk resonator; 2) combining the function of an RF circulator and a bandpass filter (BPF) within the volume of a single microwave component; and 3) by tuning its transfer function. The proposed BPFC exhibits a quasi-elliptic power transmission response in the forward direction-passband in-between four transmission zeros (TZs)-and an all-stop response in the reverse one. Reconfigurability is achieved by tuning the capacitive loads of the ferrite disk and the mixed electromagnetic coupling elements in the RF input/output. For proof-of-concept validation purposes, an S-band tunable prototype was designed, built, and measured. It demonstrated multiple levels of tuning. These include the frequency tuning of 1.27:1, the bandwidth tuning of 1.73:1, the out-of-band isolation tuning, and intrinsic switching-off.

A Single-Layer Dual-Circularly Polarized SIW-Cavity-Backed Patch Filtenna With Wide Axial-Ratio Bandwidth

A single-layer dual-circularly polarized cavity-backed patch filtenna with wide axial-ratio (AR) bandwidth is presented in this letter. The degenerated substrate-integrated waveguide (SIW) cavity modes TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">120</sub> /TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">210</sub> cooperating with the patch modes TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> /TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> are utilized to achieve a wide AR bandwidth. Simultaneously, two radiation nulls, which are inherently introduced by the SIW-cavity mode TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">110</sub> and mixed electromagnetic coupling between the cavity and patch, respectively, are realized at both band edges to achieve a bandpass filtering response. For demonstration, a sample was fabricated and tested. The measured results show that the proposed filtenna achieves an operating bandwidth of 12% with the center frequency of 10 GHz, a peak gain of 7.4 dBic, an in-band average gain of 6.7 dBic, and an out-of-band rejection level over -13 dB.

Dual‐band filter with high selectivity and wide stopband rejection

This article presents a highly selective dual-passband filter based on stepped-impedance-resonator (SIR) and mixed electromagnetic coupling. First, the surface area of the filter is effectively reduced by the triangular topology. Second, four controllable transmission zeros are introduced by source-load coupling feed and mixed electromagnetic, which increases the selectivity of the filter. Third, a perturbation structure is added to independently control the resonance points of each passband. Finally, the improved defect ground structure (DGS) is integrated to obtain wide stopband rejection. The measured S-parameters are well agreement with the simulated results, which show that the center frequencies of the two passbands are 2.4 GHz and 5.2 GHz; and the passband insertion losses are 0.85 dB and 1.6 dB; and the relative bandwidths are 14.6% and 5.7%, respectively. Besides, the structure is with six transmission zeros, and 20 dB suppression for the third harmonic and the fourth harmonic are achieved. Compared with the traditional SIR double-passband filter, this filter has many advantages, such as simple design, small size, small insertion loss, controllable frequency, high selectivity, and high spurious suppression.

Compact microstrip balanced bandpass filter with adjustable transmission zeros

A compact microstrip balanced bandpass filter (BPF) with a pair of adjustable transmission zeros (TZs) and a common mode suppression of over 20 dB in a frequency range of >2.42f 0 by using the mixed electromagnetic coupling technology has been developed. The filter TZs in differential-mode are attributed to the mixed electromagnetic coupling, and can be adjusted by the electric/magnetic coupling individually. The filter bandwidth can also be controlled by the electromagnetic coupling. The proposed balanced BPF has been fabricated and measured, and the prediction has been demonstrated.

3-D-Printed Quasi-Elliptical Evanescent Mode Filter Using Mixed Electromagnetic Coupling

This letter presents an innovative topology of evanescent mode filters with mixed electromagnetic coupling finalized to take full advantage of additive manufacturing techniques. A four-pole filter with two transmission zeroes was designed starting from a suitable equivalent circuit. The filter was built using a 3-D printer and measured. The good experimental results show the usefulness of the solution when in-line topologies are required.

A Novel Diplexer Integrated With a Shielding Case Using High $Q$ -Factor Hybrid Resonator Bandpass Filters

This letter presents a new approach for designing a high-selectivity diplexer, which is based on compact and high unloaded quality factor hybrid resonator (HR) bandpass filters. The proposed HR is composed of a microstrip line and a short-circuit coaxial line, which has great saving of space in the shielding case of RF module. Additional transmission zeros on both sides of the passband response, which are created by the source-load (S-L) coupling and mixed electromagnetic coupling scheme, can easily be realized to enhance the out-of-band rejection of the filters. A diplexer prototype at center frequencies 2.4/2.7 GHz with 3-dB bandwidth of 80/102 MHz, respectively is designed. The measured insertion losses are better than 1.5 dB for the two channels with greater than 40 dB in output isolation, which shows good agreement with simulation results.

High isolation tunable diplexer based on mixed electromagnetic coupling

In this article, a tunable diplexer based on quarter-wavelength resonators with mixed electromagnetic coupling is designed. Different coupling types are utilized to generate a transmission zero in the stopband of filter, aiming to improve the isolation of diplexer. The meander line tunable filter with a magnetic dominated coupling forms channel 1 of the diplexer, a transmission zero in upper stopband is realized. The tunable filter dominated by electrical coupling constitutes channel 2 of the diplexer, a transmission zero is produced in lower stopband of the filter. Varactor diodes are loaded at quarter-wavelength resonators for tunability of the center frequency. The proposed diplexer is both demonstrated by simulation and measurement. Experimental results show that the designed tunable diplexer has a frequency range of 0.85-1.2 GHz and an isolation of greater than 42 dB.

A wideband bandpass filter with multi-mode resonator and mixed electromagnetic coupling

In this paper, a wideband bandpass filter using multi-mode resonator and mixed electromagnetic (EM) coupling is presented. To increase the bandwidth while not enlarge the circuit size, multi-short-stub multi-mode resonator, which produces multiple resonances, is utilized. Furthermore, the capacitive gap between open ends of the stubs is utilized to realize electric coupling between the multi-mode resonator and quarter-wavelength stepped impedance resonator. Meanwhile, a high-impedance transmission line between them is used to implement magnetic coupling. This mixed EM coupling can produce transmission zero near the passband, consequently improving the frequency selectivity of proposed filter. Measured results of the filter prototype are in good agreement with the simulated ones. The filter is with an insertion loss at central frequency of 15.86 GHz about 2.5 dB, a 3 dB bandwidth about 5.72 GHz (the fractional bandwidth about 36%), and the variation of group delay over the whole passband &lt;0.28 ns. Additionally, the effective circuit size of the filter is about 0.126 λg2, where λg is the wavelength of 15.86 GHz. All these results have shown that proposed filter is promising for future high-precision imaging system or high-speed communication application.

High Selective Microstrip Bandpass Filter and Diplexer With Mixed Electromagnetic Coupling

A high selective bandpass filter and a high isolation diplexer by using mixed electromagnetic coupling have been presented. The filter transmission zeros (TZs) are attributed to the mixed electromagnetic coupling, and additional resonators are not required. TZs also can be adjusted by controlling the electric and magnetic couplings. The diplexer is fabricated and measured, and the new design is demonstrated by measurement. The diplexer has a compact size of $0.483\lambda_{\rm g}\times 0.585\lambda_{\rm g}$ , and a measured high isolation of no less than 42 dB.

High selective bandpass filter with mixed electromagnetic coupling and source–load coupling

High selective bandpass filters with a pair of transmission zeros using right-angled triangular stepped-impedance resonators are proposed and analyzed. The transmission zeros on both sides of passband are attributed to the mixed electromagnetic coupling and capacitive source–load coupling, respectively. The transmission zeros locations from the central frequency can be adjusted by controlling the mixed electromagnetic coupling and source–load coupling. The design is also suitable for dual-band bandpass filter with high frequency selectivity. Single band bandpass filters which center at 2.45GHz and 3.2GHz, respectively, and a dual-band bandpass filter which centers at 2.45GHz and 3.5GHz have been designed, fabricated and measured, the measurements have demonstrated the prediction. Experimental results show that each passband of the presented filters have a pair of transmission zeros as prediction, which improve the frequency selectivity greatly. The measured filters’ passband insertion losses are less than 2.74dB at central frequencies.