Coupled Microstrip Lines Research Articles

Compact Fano-Type Liquid Metamaterial Resonator for High-Precision Temperature Sensing

In this paper, a liquid metal mercury (Hg) based high quality-factor (Q-factor) liquid electromagnetic metamaterial unit, the Hg Fano resonator, is designed for the high-precision temperature sensing application. Such Fano resonance in the Hg-resonator is excited by the microstrip-line coupling and the resonance frequency is sensitive to the background temperature changes. Based on the high Q-factor and the temperature-sensitive features of Hg-Fano resonator, the high-precision temperature sensing performance is discussed and achieved, with numerical and experimental demonstrations. The experimental sensitivity of 11.7 MHz/°C and figure-of-merit (FOM) of 0.4/°C are obtained. The proposed compact Hg-Fano resonator-based sensor can be widely used for the wireless temperature sensing area.

The measurement of water level based on parallel-coupled lines with capacitance compensation

This paper aimed to measure the water level using parallel-coupled microstrip lines with capacitor compensation. The design and implementation were parallel coupled microstrip lines with capacitor compensation to measure the water level. The technique of parallel-coupled microstrip lines had a coupling coefficient of – 10 dB. The center frequency was 200 MHz, and the compensated capacitor was positioned at ports 3 and 4. The water level was adjusted from 0 to 20 cm in the experiment. The frequency response of the coupling factor was measured from 300 kHz to 2 GHz. The coupling coefficient at 200 MHz was – 11.45 dB at 0 cm water level, where a shift of frequency decreased continuously. This technique was simple to follow, as the sensor was small and inexpensive.

Compact Shared-Aperture Dual-Band Dual-Polarized Array Using Filtering Slot Antenna and Dual-Function Metasurface

This article presents a shared-aperture dual-band dual-polarized antenna array for fifth-generation (5G) mobile communication. Within one radiating aperture, four higher band (HB) patch antenna elements are placed over the lower band (LB) full-wavelength slot antenna. The proposed array is miniaturized by bending the ground plane of the slot antenna. Suppression of cross-band mutual coupling and scattering is achieved by using the filtering performance of the slot antenna and a dual-function metasurface. The filtering performance of the slot antenna is realized using coupled microstrip lines inside the radiating slot and open-ended stubs on the feeding lines. The dual-function metasurface operates as an artificial magnetic conductor reflector in the LB and bandpass frequency-selective surface in the HB. By placing the dual-function metasurface behind the slot antenna, the radiation of the slot antenna is enhanced in the LB but not HB, and the negative effect of its HB scattering on the HB antennas is reduced. The working mechanism is explained in detail. The measured and simulated results demonstrate that the proposed array has stable radiation patterns in the bands of 0.69–0.96 and 3.4–3.7 GHz with a high cross-band isolation of over 32 dB and is more compact than the previous works.

A W-Band Amplifier With a New Wide-Band Interstage Matching Technique Using Self-Resonance of a Microstrip-Coupled Line

A new interstage matching technique is presented for design of a wide-band multi-stage amplifier using commercial 60- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> m GaN-on-silicon technology in the W-band. The proposed interstage matching network is designed as a two-pole conjugated impedance matching approach for wideband characteristics using low-characteristic impedance transmission lines and an optimized microstrip-coupled line. In particular, the microstrip-coupled line provides strong resonance at the desired frequency, enabling optimal conjugate impedance matching of both edge and intermediate frequencies simultaneously. The implemented W-band three-stage amplifier using the proposed interstage matching technique exhibited a small-signal gain above 14.1 dB from 75 to 103 GHz. Also, the output power between 92-100 GHz was greater than 25 dBm, and the maximum output power at 96 GHz was 25.8 dBm. The W-band amplifier was designed with an area of 2 mm × 1.2 mm.

Tunable Filtenna With DGS Loaded Resonators for a Cognitive Radio System Based on an SDR Transceiver

This paper introduces the design of a filtenna for cognitive radio systems. Four varactor diodes, which are inserted in the bandpass filter, are used to achieve the desired tunability. The proposed bandpass filter is integrated with a wideband monopole antenna. The bandpass filter is achieved by using two coupled defected ground structure (DGS) resonators and two coupled microstrip lines ended with two stubs. The monopole antenna is designed to operate in a frequency band from 1.3 GHz to 3 GHz. The four varactor diodes are used to tune the antenna resonance frequency from 2.7 GHz to 2 GHz when the capacitance increases from 1.55 pF to 2.67 pF. The performance of the proposed filtenna is validated by simulation and measurements from a fabricated prototype. Finally, the proposed filtenna is tested using the Software Defined Radio (SDR) platform bladeRF. This transceiver can transmit and receive in a wide frequency range of 0.3 GHz up to 3.8 GHz, which makes it suitable for testing the proposed reconfigurable filtenna.

Wideband Highly-Selective Bandpass Filtering Branch-Line Coupler

This paper presents a novel design of a wideband highly-selective bandpass filtering branch-line coupler (FBLC). By integrating a coupled microstrip line, and an open-ended stub at each port of a single-section BLC, bandpass filtering characteristics with excellent selectivity and broad operating bandwidth have been achieved. The proposed circuit has been verified through EM simulations and physical measurements of the fabricated prototype. Experimental results demonstrate over 71-percent fractional bandwidth (2.25 GHz to 4.74 GHz) with a power imbalance lower than 0.5 dB. At the same time, the measured return loss and isolation are better than 15dB with the phase imbalance of 5 ± 5°. This level of performance, especially in terms of bandwidth and selectivity, has not been reported in the literature thus far.

Tunable wideband THz graphene-based artificial magnetic conductors

Graphene-based artificial magnetic conductor (AMC) structures featuring wideband and tunable responses at terahertz frequencies are presented. The unit cells of the proposed structures comprise curved coupled microstrip line (CCML) resonators, in which small graphene patches are added for electrical tuning. An advantage of the present structure is that the full range of graphene chemical potential, from 0 to about 1 eV, can be used to tune the center frequency; therefore the AMC is tunable in a larger frequency range, for which the return loss remains near 0 dB. This feature is missing in the previous tunable graphene-based AMC structures. A typical design in the present work yields a fractional bandwidth of 45% and an electrically tunable center frequency in a range from 3.7 to 4.4 THz.

An EH₀-Mode Microstrip Leaky Wave Antenna on Differentially Excited Coupled Line for Transversal Single-Beam Radiation

This communication presents a method to make the EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -mode microstrip leaky wave antenna (MLWA) radiate single beam in its transversal plane based on the differentially excited coupled microstrip line structure with low cross-polarization. The conventional EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -mode MLWA is constructed by periodically loading a series of shorting pins along the center line of the uniform line, but it mainly radiates dual beams in its transversal plane. If a ground plane approaches to one of its edges with rotation of the whole structure, only one radiation aperture will be left to radiate single beam in the broadside direction. Herein, a planar differentially excited coupled line configuration is implemented to validate the proposed method and simultaneously inherits the original outstanding characteristic of freely designed narrow strip width. In design, a unified equivalent model is first established to provide insight into its radiation principle through propagation characteristics. Then, the dispersion and radiation properties are further investigated under mixed geometrical parameters. Finally, a prototype MLWA with transversal single-beam radiation is designed and fabricated with good agreement between the simulated and measured results, which validates the proposed method for designing a single-beam EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> mode MLWA.

Compact balanced tri‐band bandpass filter based on stub loaded resonator with high selectivity

A compact balanced microstrip tri-band bandpass filter (BPF) using short and open stubs loaded resonators (SOSLRs) is achieved in this article. Three differential-mode (DM) passbands can be adjusted by properly controlling the dimensions of the loaded short and open stubs, and the first and third DM center frequencies can be implemented independently. By introducing interdigital coupling microstrip lines, five transmission zeros (TZ) are implemented to achieve a higher selectivity. The positions of TZs can be controlled by adjusting the coupling gaps between SOSLRs and interdigital coupling microstrip lines. In addition, balanced microstrip line to slotline transformation structures is introduced as the feed structure, which can be used to block the common-mode (CM) transmission inherently. Therefore, the DM performances are independent from the CM responses, which can simplify the design procedure significantly. For demonstration, a balanced tri-band BPF centered at 1.57, 2.45, and 3.5 GHz was fabricated and measured. Comparison with other reported balanced BPFs indicates that the proposed design exhibits the advantages of high selectivity and good CM suppression responses.

Design of Coupled Slow-Wave CPW Millimeter-Wave Bandpass Filter Beyond 100 GHz in 55-nm BiCMOS Technology

The design and experimental results of millimeter-wave bandpass filters (BPFs) implemented in 55-nm BiCMOS technology and operating around 120 GHz are presented in this article. Slightly modified coupled line filters' structures are used in the designs. It allows generating the transmission zero at the upper stopband, leading to the selectivity of enhanced filters. The coupled line structure is implemented in two technologies, microstrip coupled lines and coupled slow-wave (SW) coplanar waveguides (CS-CPWs). The latter shows more design flexibility, allowing to reach a better filtering performance than the microstrip filters, i.e., better in-band flatness and higher selectivity. Good agreement is achieved between simulation, modeling, and measurement results. Also, the overall length of the filter based on CS-CPWs is smaller as compared to the filters based on the microstrip lines, thanks to the SW propagation.

Dual-Polarized Nonreciprocal Spatial Amplification Active Metasurface

This letter presents a dual-polarized nonreciprocal active metasurface (MTS) for spatial electromagnetic wave amplification. The MTS is designed based on receiving, amplifying, and reradiating scheme. Two square patch antennas printed on the opposite sides of two-layer substrates are used as receiving and reradiating antennas, respectively. A T-shaped microstrip line coupling structure is adopted to achieve impedance matching and dc-block function. Two bipolar transistors, which are place on a pair of orthogonal microstrip feed lines, are used as amplifiers to achieve dual polarization spatial amplification of the electromagnetic wave. A prototype MTS is fabricated and tested to verify the design. The measured effective spatial amplification coefficients higher than 0 dB has a band from 4.88 to 5.19 GHz with the peak value of 10.4 dB. Besides, the proposed MTS is insensitive to polarization. The spatial amplification coefficients variation for different polarization is below 0.6 dB. The proposed MTS could be used in the radio frequency transceiver systems to reduce the pressure of the amplifier on the circuit board.

A simple triple‐band coupled line filtering power divider design

AbstractIn this letter, a triple‐band filtering power divider (FPD) is proposed for passive circuit implementation with a good isolation. The proposed triple‐band FPD is composed of coupled microstrip lines by applying a comprehensive design method. Based on the design method and developed topology, the employed coupled microstrip resonators, the input/output feedlines as well as isolated resistor are properly arranged to achieve a desired triple‐band filtering and isolation response. To validate our design concept and method, a triple‐band FPD operating at 2.3–2.33, 2.39–2.42, and 2.5–2.53 GHz is implemented with good return loss and isolation. Measured and simulated results are in good agreement.

종이접기와 키리가미 이론에 기반한 3차원 T-자형 다이폴 안테나 설계

In this study, the design of a 3D foldable T-shaped dipole antenna inspired by origami and kirigami theory is presented. The origami- and kirigami-inspired techniques map 2D to 3D space. Moreover, the lamina emergent torsional (LET) joint is designed to fold the planar structure. The proposed antenna, including the LET joint, is printed on a planar 0.5 mm thick FR4 substrate. The proposed antenna is fed by a capacitively coupled microstrip line to achieve a 20 % fractional bandwidth (2.7~3.3 GHz), with a measured antenna gain value of 6.5 dBi.

Design, Optimizing and Improvement of Microstrip 5G Patch Antenna Parameters Using Keysight Advanced Designed System (ADS)

This paper described the microstrip Patch antenna of 5G mobile phone with calculation, simulation, and optimization method by using the ADS Simulation software. The patch antenna sized could be applied for various applications and designed wideband, multiband frequency operation. Bandwidth improvement of 3500 MHz is progressed after optimization and the patch can operate for wideband application. In this paper, the calculation method of inset feed patch antenna, designed with simulation by using the calculation method. However, some of the calculations are matched the designed frequency. Therefore, we optimized the design with length only. Moreover, the author implemented the designs that the MLIN (Microstrip Line) is based on the patch distributive line and Asymmetric Edge Coupled Microstrip Lines is designed as the MACLIN3 and MLOC mean microstrip location design.

Compact broadband high‐efficiency power amplifier using terminated coupled line filter matching network

This article presents a compact broadband high-efficiency power amplifier (PA) with a filtering structure. Unlike the cascaded filter behind the traditional PA, the proposed cascaded branch load coupling microstrip line structure is used to design the output matching network (OMN) of the PA. It plays the roles of impedance matching and filtering, which is called a filtering OMN, the overall size of the circuit will be reduced. Two coupled microstrip lines cascaded are used to extend the working bandwidth, and a microstrip line is loaded to the port of the coupled microstrip lines to ensure high selectivity and good out-of-band performance. For verification, a broadband high-efficiency PA is designed and manufactured by using CGH40010F GaN HEMT. Measurements demonstrate that in the range from 1.2 to 3.6 GHz, the saturated output power is from 39.8 to 41.8 dBm, the drain efficiency (DE) with a 62%–73%, and the gain is between 9.9 and 11.7 dB.

Multi‐ and dual‐tuned microstripline‐based transmit/receive switch for 7‐Tesla magnetic resonance imaging

AbstractThis article introduces two new designs of transmit/receive switches for 7‐Tesla magnetic resonance imaging. Both designs based on a microstripline coupler technology. In the first design, a different single frequency signals can be handled to/from a radio frequency coil using smart tuning network. In the second design, a dual‐tuned 1H/23Na transmit/receive switch is designed to handle a dual resonant signal to a dual resonant 1H/23Na coil, simultaneously and without tuning. In transmit and receive, the first design achieved good matching (‐20 dB), and low insertion loss (0.78 dB) for the 1H, 19F, 31P, 13C, and 23Na magnetic resonance signals with high isolation (61 dB). Similarly, the dual‐tuned 1H/23Na switch achieved good matching (&lt;−11.5 dB) and low insertion loss (1.0 dB) with high isolation (67 dB), whereas for 1H/31P switch, good matching has been achieved (&lt;−12 dB) and low insertion loss (0.96 dB) with high isolation (62 dB). The first proposed switch enables the use of the same switch with different coils resonating at Larmor frequencies of different atomic nuclei. The second switch can handle a dual resonant signal to a single dual resonant coil. The first design is promising in reducing the costs by using the same switch with different coils. The second design is promising in the integration with multichannel dual resonant coil.

A high-selectivity double-mode SIW bandpass filter utilizing the modified parallel coupled microstrip lines

ABSTRACT In this article, a high-selectivity double-mode substrate integration waveguide bandpass filter utilizing modified parallel coupled microstrip lines (MPCML) is presented. The designed method is analyzed in detail. Six metal vias are designed to perturb TE-101 mode and TE-103 mode. The resonant frequency of the perturbed TE-101 mode is shifted to high frequency, close to that of TE-102 mode, which caused the formation of passband. The resonant frequency of the perturbed TE-103 mode is shifted to high frequency, improving out-of-band performance. Simultaneously, the coplanar waveguide structure is used to adjust the external quality factor. Two rectangular slotlines are introduced to adjust center frequency and bandwidth slightly. Two rectangular stubs are designed for better source and load matching. Three transmission zeros (TZs) are obtained to improve the selectivity. The designed MPCML promotes the generation of TZs. Another TZ is obtained by the coupling between TE-102 mode and TE-103 mode. The designed filter operates at 14.4 GHz with bandwidth of 800 MHz. The measured return loss is better than 15 dB, and the minimum insertion loss is 1.60 dB. The measurement is agreed with the simulation.

Wideband High-CMRR Fully Differential Couplers Using Multimode Star-Junction

This article presents novel wideband fully differential hybrid and rat-race couplers whose design methodologies are based on the multimode star junction. The couplers benefit from the even and odd modes of the slotted-microstrip sections that constitute the junction to realize compact equivalent transmission lines, while they exploit the characteristics of the slotline to achieve differential ports with wideband performance and high common mode rejection ratio (CMRR). The differential signals are extracted through slotline to coupled-microstrip line transitions that maintain the phase relation between the ports. Measurements, which are in good agreement with electromagnetic (EM) and circuit simulations, confirm the theoretical predictions. The proposed hybrid coupler has 12% and 33.3% 15-dB return loss (RL)/isolation and 3-dB fractional bandwidths (FBWs), respectively, $0.6\lambda _{g} \times 0.6\lambda _{g}$ size, and 0.6-dB insertion loss (IL). While the proposed rat-race coupler has 32.5% and 35% 15-dB RL/isolation and 3-dB FBWs, respectively, $0.7\lambda _{g} \times 0.7\lambda _{g}$ size, and 0.6-dB IL. For both structures, the CMRR exceeds 50 dB at the operating frequency and the CM rejection FBW exceeds 300%.

High-Q Hg-anapole resonator with microstrip line coupling for high-precision temperature sensing applications

In this paper, to achieve a high-precision temperature sensing, a modified anapole resonator based on the liquid–metal (Hg) with high Q-factor and large thermal-sensitivity properties is proposed. The high-Q resonance of the designed Hg-anapole resonator is excited by a simple microstrip coupling line with large electromagnetic energy coupling rate. The detailed numerical optimization and experimental demonstration are discussed, and the measured temperature sensitivity of 17.14 MHz/°C and figure-of-merit (FOM) of 0.3/°C are achieved based on the proposed Hg-anapole resonator. This kind of liquid high-Q metamaterial unit can be widely used to realize the high-precision sensing.

Design of microstrip coupled-line bandpass filter

This project contains basic information, design, 3D projection, simulation, and analysis of Microstrip Bandpass Filter. The filter was composed of the feed lines connected to the two ports with the parallel coupled lines between them. The separation between these elements is reduced to the minimum for the purpose of reducing the error. Ultimately, the microstrip bandpass filter was designed with a 400 MHz bandwidth. We end up with these result: at the 4.43 GHz, S11 parameter is -9.868 dB and S22 is -1.808 dB, while at the 4.83 GHz, S11 is -9.995 dB and S22 is -1.826 dB.