Grounded Coplanar Waveguide Research Articles

Coplanar waveguide ground potential imbalance as a source of useful signal in near-field scanning microwave microscopy

Various techniques are available in order to obtain information on samples of a different nature in near-field scanning microwave microscopy (NSMM), with transmission-line resonator (TLR) techniques considered the most advanced in terms of sensitivity and resolution. In this paper, we focus on the development of TLR-based NSMM supplied by a new source of useful signal: coplanar waveguide ground potential imbalance. Electromagnetic modeling of the device and experimental scanning of two planar structures are conducted to examine the performance of the proposed technique. Both modeling and experimental results demonstrate the ability to distinguish symmetric inhomogeneity positions with respect to the central conductor of the coplanar waveguide by the phase of the imbalance signal. The thin-film structure scanning procedure displays the possibility of the proposed approach to resolve low-contrast structures with an accuracy of up to 98.7%.

A compact differential branch‐line coupler using folded substrate integrated suspended parallel strip line

AbstractThis letter presents a compact fully differential branch‐line coupler. It is composed of folded substrate integrated suspended parallel strip line (SISPSL), which can generate slow‐wave effect and help reduce the circuit size. The used SISPSL type line is a fusion of double‐sided parallel‐strip line (DSPSL) and substrate integrated suspended line (SISL), which has the advantage of self‐packaging as compared with traditional DSPSL exposed to air. A DC to 30‐GHz differential transition from grounded coplanar waveguide (GCPW) to SISPSL is designed to test the SISPSL differential coupler. The implemented SISPSL branch‐line coupler has a compact size of 0.056 λg × 0.05 λg.

De‐embedding calibration for an electromagnetic dual probe using GCPW

AbstractAn ultrawideband de‐embedding calibration method (DCM) for a dual probe is proposed in this paper. Different from the conventional calibration method (CCM), in which a microstrip calibrator and the dual probe form a three‐port calibration network, the proposed calibration system is a four‐port network. By using two different lengths of grounded coplanar waveguide (GCPW) calibrators, namely line‐kit and through‐kit, the de‐embedded ‐parameter model of the calibration network is obtained. Measured results show that the ripple of the DCM with GCPW reduced by 59% of the CCM with the microstrip calibrator, and the phase delay has been almost compensated. In addition, the proposed method reduces the attenuation by approximately 0.7 dB at 10 GHz and 1.15 dB at 20 GHz. The calibration results indicate that the working frequency of the DCM is up to 22 GHz.

Differential magnetic field probe calibration based on symmetric de‐embedding technology

AbstractThe de‐embedding calibration method has been proposed to achieve high‐precision calibration for a single port electric field or magnetic field probe, which can effectively eliminate the calibration ripple. However, the method's effectiveness for a four‐port calibration system has not been verified yet. In this paper, a four‐port de‐embedding calibration method with a differential magnetic field probe is proposed, and its effectiveness is proved. Two symmetric grounded coplanar waveguide transmission lines are applied in the proposed method to solve the ABCD‐matrix of the embedded part of the calibrator. The de‐embedded S‐parameter model of the four‐port calibration system for differential magnetic field probe can be obtained. The calibration results indicate that the proposed method can also reduce the calibration ripple and compensate for the attenuation caused by the calibrator. Compared with the traditional calibration method using a microstrip line calibrator, the ripples of the proposed method can be reduced by 34%. The analysis results of the frequency interval of the ripple (FIR) in different methods show that the de‐embedding method can reduce the FIRs (except around 1.2 GHz) caused by the reflection of the calibrator and retain the FIR (about 1.2 GHz) caused by the reflection of the probe itself.

Wideband Vertically Polarized Planar Endfire Antenna Based on Spoof Surface Plasmon Polaritons

A novel wideband vertically polarized planar end-fire antenna based on the first and the second high-order modes of Spoof Surface Plasmon Polaritons (SSPPs) is proposed in this letter. A double-sided SSPP transmission line (TL) is used to produce vertically polarized radiation. By replacing the uniform stub in the conventional SSPP cells with a step-impedance-resonator (SIR) shaped stub, the bandgap between the first and the second high-order modes is eliminated. The double-sided SIR-shaped SSPP cells are tilted to make the maximum radiation point in the end-fire direction. Dielectric covers perforated with air vias are added to the top and bottom surfaces of the SSPP TL to generate end-fire radiation and enhance antenna gain. A grounded coplanar waveguide to double-sided parallel-strip line transition is designed to feed the radiator. A prototype of the proposed antenna has been fabricated and measured. The proposed antenna achieves a fractional bandwidth of 91.6% from 12.9 GHz to 34.6 GHz and a peak gain of 17.3 dBi.

CPW-fed dual-element metamaterial inspired multiband antenna using simple FSS for gain enhancement

This article presents a dual-element metamaterial-inspired co-planar waveguide (CPW) fed elliptical antenna using a simple compact frequency selective surface (FSS) for multiband wireless applications. The designed antenna is fabricated on a cheap FR-4 substrate (εr = 4.4) with 40 × 40×1.6 mm3 dimensions. Dual complementary split ring resonators (CSRRs) loaded in the CPW ground create multiband characteristics, which are analyzed using the quasi-static design equations and the ANSYS HFSS EM simulator. FSS has been proposed as a reflector for the antenna to increase its gain. The FSS unit cell's angular stability has been analyzed using transverse electric (TE) and transverse magnetic (TM) polarization, and it has been determined to be 60°. The FSS integrated antenna offers measured bandwidths of 2.67 – 3.38 GHz (23.66 %), 3.77 – 4.17 GHz (10.25%), 4.91 – 5.93 GHz (19.61 %), and 7.28 – 8.93 GHz (20.24 %). The FSS integrated antenna shows nearly omnidirectional radiation patterns in all resonating bands with the highest gain of 9.72 dBi and measured radiation efficiency greater than 91 % in all the bands. The reported 'antenna with FSS' is appropriate for multiband wireless technologies as it covers IEEE 802.16 WiMAX, n77 5G NR, 5G Wi-Fi, WLAN, ISM and satellite spectrums.

A 220 GHz to 325 GHz Grounded Coplanar Waveguide Based Periodic Leaky-Wave Beam-Steering Antenna in Indium Phosphide Process

This paper presents a novel periodic grounded coplanar waveguide (GCPW) leaky-wave antenna implemented in an Indium Phosphide (InP) process. The antenna is designed to operate in the 220 GHz–325 GHz frequency range, with the goal of integrating it with an InP uni-traveling-carrier photodiode to realize a wireless transmitter module. Future wireless communication systems must deliver a high data rate to multiple users in different locations. Therefore, wireless transmitters need to have a broadband nature, high gain, and beam-steering capability. Leaky-wave antennas offer a simple and cost-effective way to achieve beam-steering by sweeping frequency in the THz range. In this paper, the first periodic GCPW leaky-wave antenna in the 220 GHz–325 GHz frequency range is demonstrated. The antenna design is based on a novel GCPW leaky-wave unit cell (UC) that incorporates mirrored L-slots in the lateral ground planes. These mirrored L-slots effectively mitigate the open stopband phenomenon of a periodic leaky-wave antenna. The leakage rate, phase constant, and Bloch impedance of the novel GCPW leaky-wave UC are analyzed using Floquet’s theory. After optimizing the UC, a periodic GCPW leaky-wave antenna is constructed by cascading 16 UCs. Electromagnetic simulation results of the leaky-wave antenna are compared with an ideal model derived from a single UC. The two design approaches show excellent agreement in terms of their reflection coefficient and beam-steering range. Therefore, the ideal model presented in this paper demonstrates, for the first time, a rapid method for developing periodic leaky-wave antennas. To validate the simulation results, probe-based antenna measurements are conducted, showing close agreement in terms of the reflection coefficient, peak antenna gain, beam-steering angle, and far-field radiation patterns. The periodic GCPW leaky-wave antenna presented in this paper exhibits a high gain of up to 13.5 dBi and a wide beam-steering range from −60° to 35° over the 220 GHz–325 GHz frequency range.

Dual nanocomposite materials that enhance the radiation characteristics of flexible circular antenna

A novel dual nanocomposite filled circular shaped flexible slot antenna is introduced for WLAN/WiMAX/5G/Wi-Fi applications. The circular radiating patch is given two slots that are filled with nanocomposite materials PANI/CCo and PDMS/AgNW, which enhances antenna radiation properties in both lower and upper band independently. The antenna is fabricated deploying a coplanar waveguide (CPW) fed system that encompasses a patch featuring a circular shape and CPW ground combined with a circular ring shape. The dual band is formed by introducing a narrow rectangular slot on the circular radiating patch and is designed for a mid-frequency 3.85 GHz, of two resonance frequencies. Different bending radii are used to evaluate antenna flexibility, and findings are in good match for a flat antenna. With good radiating qualities over the whole dual band, the suggested fabricated antenna covers the 2.4/5.2/5.8 GHz WLAN, 2.5/5.5 GHz WiMAX, 2.3/2.6 GHz 5G, 2.4/4.9/5.2/5.5/5.8 GHz Wi-Fi, and 5G SUB 6 GHz bands.

Balanced-to-Single-Ended Filtering Power Divider Using Multilayer Mixed-Mode Magic-T

A type of balanced-to-single-ended (BTSE) filtering power divider (FPD) using multilayer mixed-mode magic-T is reported. Based on grounded coplanar waveguide (GCPW) to slotline transitions, a mixed-mode magic-T is firstly discussed. It attains out-of-phase and in-phase wideband distributed responses by means of the balanced port E and the single-ended port H, respectively. Then, by coupling the designed mixed-mode magic-T with a stub-loaded resonator (SLR), a BTSE FPD with its port H terminated by a 50-ohm load is proposed. Due to the employed microstrip SLR along with the coupled pair of L-shaped slotline sections, the designed FPD can feature a second-order highselectivity differential-mode (DM) filtering response with two close-to-passband transmission zeros (TZs) and high broadband common-mode (CM) rejection. Moreover, for experimentaldemonstration purposes, two proof-of-concept prototypes corresponding to a mixed-mode magic-T and a BTSE FPD are developed and tested. The mixed-mode magic-T is measured with a BTSE 10-dB return-loss bandwidth from 2.05 to 3.78 GHz and a single-ended-to-single-ended (SETSE) 10-dB return-loss bandwidth from 1.5 to 4.5 GHz, respectively. The measured BTSE FPD features a 10-dB return-loss DM bandwidth of 8.36% along with power isolation levels above 17.7 dB at the output ports and two TZs located 2.74 and 3.55 GHz, respectively.

An Omnidirectional CPW Leaky-Wave Antenna With Steering Conical Beam

This paper proposes a planar omnidirectional leaky-wave antenna with steering conical beam and stable radiation through the broadside on the periodically modulated coplanar waveguide (CPW). The radiation characteristics of the leaky CPW cells are investigated according to different-shaped open-end slots and various widths of the substrate layer. Then, the omnidirectional conical radiation beam is obtained by etching exponentially tapered open-end slots on the CPW ground parts and modifying the width of the substrate layer properly. Under the frequency balanced condition, a pair of additional series inductive slots are etched on the modulated CPW to balance the Bloch impedance and suppress the open-stop band effect. An antenna demonstration is designed as verification. The measured results validate the simulated results experimentally, confirming the conical beams in the H-plane and the wide-angle beam scanning of −60° to 17° in the E-plane.

Flippable and Hermetic E-Band RWG to GCPW Transition With Substrate Embedded Backshort

In this article, a novel millimeter wave (mm-wave), fully hermetic and flippable transitioning structure between grounded coplanar waveguides (GCPWs) and rectangular waveguides (RWGs) is introduced. This transition, realized through standard printed circuit board (PCB) technology, can be employed to feed a waveguide (WG) compliant device on any face of a board given its flexibility in trace routing and component placement. The proposed structure utilizes a mix of transmission line and substrate integrated waveguide (SIW) interconnected with an in-substrate embedded back-short. The transition, in all its configurations, targets a fractional bandwidth (FBW) wider than 20% to cover the commercial <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$</tex-math> </inline-formula> -band spectrum. Moreover, at center frequency the predicted insertion loss (IL) for both normal and flipped transitions is 0.4 and 0.46 dB, respectively. Parametric and yield analyses, together with postmanufacturing inspections have been performed to assess the robustness of the design and to identify the critical manufacturing inaccuracies. The experimental validations confirm the wideband operation with an IL bounded below 2.3 dB for the worst case of a back-to-back configuration.

CPW fed shovel shaped super wideband MIMO antenna for 5G applications

A shovel shaped antenna operating from 4.1 to >60 GHz to cover C/X/Ku/K/Ka/Q/U bands along with 5G bands n257/n258/n259/n260/n261/n79/60 GHz is presented in this paper. It consists of a modified square patch, tapered feed line and modified defected coplanar waveguide ground planes. A half-wavelength split ring resonator (SRR) is used to achieve X-band satellite downlink (6.8–7.8) GHz band notch. It has dimensions of 20 × 14 mm2, quasi-stable radiation patterns, a maximum peak realized gain of 9 dBi, fidelity factor > 50%, |S21| > 32 dB and linear S21 phase response. It’s two element spatial diversity configuration has footprint of 20 × 36 mm2, operating bandwidth of 4.3 to >60 GHz with notch band characteristics and isolation >15 dB due to hybrid decoupling structure. The pattern diversity configuration has footprint of 20 × 41.5 mm2, impedance bandwidth of 4.3 to >60 GHz for Port 1 & 3.9 to >60 for Port 2 and isolation >21 dB due to hybrid decoupling structure. Both MIMO antennas have ECC≤0.01, DG≅10, TARC < -10 dB, ηmux > -3.5 dB and CCL≤0.3 b/sec/Hz and channel capacity of ∼11.34b/sec/Hz. The proposed antenna geometries are dominating previously reported structures in terms of superwide bandwidth, compact dimensions, high BDR ∼3335, high peak gain and good diversity performance with less intra element spacing.

Ultrawideband De-Embedding Calibration for Magnetic Field Probes by Using Symmetric GCPW Calibrators

Microstrip line is commonly used as a calibrator for probe calibration. However, some issues need to be addressed for high frequency application, such as ripple and attenuation caused by the embedded part of the calibrator. In this paper, an ultra-wideband de-embedding calibration method (DCM) for magnetic field probe is proposed. Two symmetric non-soldering grounded coplanar waveguide (GCPW) calibrators, including Through and Line standards, are used to solve the de-embedded <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> -parameter matrix of a 3-port calibration system. Compared with the traditional calibration method (TCM), the proposed method can reduce the influence of the reflection and attenuation caused by the embedded part and preserve the intrinsic properties of the probe itself. By using the DCM with a symmetric and good matched GCPW calibrator, the ripples of the DCM decreases by 6.57 dB, which is 82 % of the TCM with a microstrip line, and the attenuation has been compensated by about 0.7 dB at 10 GHz. In addition, a new characterization method of common mode suppression ratio for H-field probe is also presented, and it is applicable to conducted emissions measurement in which a probe can detect signals without 90° rotation.

Fully Aerosol Jet-Printed Passive Components for 140–220-GHz Operation

This letter focuses on the unique capabilities that aerosol jet printing (AJP) provides for manufacturing electronics at near-THz frequencies. For the first time, we demonstrate fully aerosol jet-printed passive components above the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$</tex-math> </inline-formula> -band. Dielectric substrates and conductors are printed on metal carriers via AJP. These components include microstrip (MS) transmission lines (TLs) and radial stubs, and utilize vialess grounded coplanar waveguide (GCPW)-to-MS TL launches. Two separate sets of components and calibration structures are realized, for two different dielectric thicknesses. For the TLs, measured from 140 to 220 GHz, the average loss varies from 0.86 to 2.6 dB/mm. The radial stub return loss, measured from 200 to 220 GHz, is closely aligned with simulations.

Wideband SIW based slot antenna for RADAR applications

In this case, a substrate integrated waveguide technology is used in conjunction with a cavity-backed slot antenna. The modified slot antenna, in comparison to the dumbbell-shaped slot, not only adds numerous additional resonance spots, but it also enables the antenna to attain a better gain. In addition to this, the high-order resonant modes that are contained inside the sub cavity may be stimulated by the ground coplanar waveguide feeding structure if the high-order modes are brought into close proximity with one another. Based on the results of the test, it has been determined that the suggested antenna achieves an impedance bandwidth of 26.7% between 18.2 and 23.8 GHz and a peak gain of 9.5 dBi at 20.4 GHz. At each of the three frequencies that were tested, the cross-polarization levels of the antenna are around 40 dB. Antennas are recognised as being among the most important parts of any communication system. Because of this, antenna design is now one of the most active areas of study within the field of communication studies. In contrast, applications like as air traffic radar, satellite communications, and point-to-point terrestrial connection demand highly concentrated radiation patterns that also have a wideband and high gain. Because of this more focused radiation pattern, there will also be an increase in the communication range.

Method to Change the Through-Hole Structure to Broaden Grounded Coplanar Waveguide Bandwidth.

A grounded coplanar waveguide (GCPW), as a millimeter wave special transmission line, can be used to calibrate broadband oscilloscope probes. A method to change the through-hole structure to widen the GCPW is investigated in this paper. The effect of the through-hole array on the band-width of the GCPW is investigated and verified using COMSOL Multiphysics simulation software. Finally, the S-parameters of the fabricated GCPWs are measured by a vector network analyzer, and the results show that they have an insertion loss > -3 dB and return loss < -10 dB in the frequency range of DC to 60 GHz, which satisfies the design requirements.

Electric Field Probe De-Embedding Calibration Based on Through and Line Standards

The electric field (E-field) probe has been widely used for electromagnetic interference diagnosis in IEC61967-3. But with the increase in detection frequency, the calibration error caused by the error box of the calibrator can not be ignored. The error in the traditional calibration method (TCM) directly affects the measurement results of the E-field probe. In this paper, a de-embedding calibration method (DCM) is applied to two typical E-field probes (Probe A and Probe B). The DCM can compensate for the effect of the error box and improve calibration accuracy. Different from the TCM using microstrip line as a calibrator, the calibrator of the DCM, as a cost, consists of auxiliary Through standard and primary Line standard. Further, two sets of calibrators for the DCM are designed based on microstrip (MS) structure and grounded coplanar waveguide (GCPW) structure, respectively. Compared with the calibrator of the DCM with MS, the calibrator of the DCM with GCPW is easier to achieve high symmetry. The test results show that the DCM with GCPW can improve the accuracy well, and the symmetry of the calibrator is very important for the DCM at high frequencies. Compared with the TCM with MS, the ripples of the DCM with GCPW can be reduced by 83.6 %. Compared with the TCM with GCPW, the ripples of the DCM with GCPW can be reduced by 50 %, and the attenuation is compensated by 1.3 dB at 20 GHz.

Mode Composite Substrate Integrated Coaxial Line Based on Substrate Integrated Coaxial Line and Periodic L-Shaped SSPP Structure

In this paper, a mode composite substrate integrated coaxial line (MCSICL) is proposed for transmitting fundamental mode and first high-order mode in dual frequency bands. The MCSICL consists of substrate integrated coaxial line (SICL) and periodic L-shaped spoof surface plasmon polariton (SSPP) structure etched on the inner conductor of the SICL. By introducing the L-shaped SSPP structure, the bandwidth of the fundamental mode of the SICL can be suppressed without changing the cut-off frequency of the first high-order mode. Therefore, the proposed MCSICL can transmit signals at the low-frequency band with the fundamental mode and at the high-frequency band with the first high-order mode. The equivalent circuit model is built to analyze the propagation properties of the MCSICL. In addition, to excite the two modes independently, a grounded coplanar waveguide (GCPW) to MCSICL transition and a microstrip line (ML) to MCSICL transition are designed. The MCSICL with the transitions is fabricated under the printed circuit boards (PCB) process. Measurement results show that the MCSICL can propagate the fundamental mode from dc to 30 GHz and the first high-order mode from 42 to 60 GHz, and the isolation between the two modes is larger than 30 dB.

Planar Leaky-Wave Antenna Featuring Wideband Fixed-Beam Radiation and Tailorable Directional Angle for Millimeter-Wave Applications

Inspired by the well-known power/energy leakage phenomenon between an unshielded grounded coplanar waveguide (GCPW) and its neighboring parallel-plate waveguide (PPW), a class of simple, low-cost, and planar leaky-wave antennas (LWAs) exhibiting wideband fixed-beam radiation and tailorable directional angle are systematically investigated and developed for millimeter-wave applications. The capability of providing wideband fixed-beam radiation (desired) and the inflexibility of altering the beam’s directional angle (undesired) are first studied and revealed concerning a uniform GCPW LWA. Then, to freely tailor its beam angle while maintaining such wideband radiation, three effective engineering techniques, i.e., using periodic GCPW/PPW and altering the PPW’s pitch angle, have been proposed and separately examined. Two LWAs using part of these techniques are modeled, fabricated, and measured for demonstration purposes. Simulated and measured results are in good agreement, and both exhibit the expected wideband fixed-beam radiation and tailorable directional angle. Due to the merits of simple configuration, well-behaved electrical behaviors, and good design flexibilities, our proposed GCPW LWAs may be potentially deployed for millimeter-wave systems such as 60-GHz point-to-point communications.

Substrate Integrated Waveguide Based Cavity-Backed Circularly-Polarized Antenna for Satellite Communication

This article presents the methodology to design a single-fed circularly-polarized antenna with low front-to-back ratio (FBR). A circular-patch (CPatch) antenna has been incorporated within the rectangular-cavity, made of, substrate integrated waveguide (SIW). The size of the CPatch and the SIW cavity has been chosen appropriately, in a manner, that the both resonators dominant mode coincide. This arrangement has been adopted to realize the basic radiating unit with no surface-wave and the significantly lower FBR. The circularly polarization has been excited through shorting the periphery of CPatch radiator to the “one of the two metallic grounds” of this SIW cavity. The patch periphery has been shorted from two distinct points, separated by the quarter wavelength—over center frequency of working band. The antenna has been designed and manufactured over Rogers RT/Duroid 5880 substrate with dielectric constant (εr) of 2.2, loss-tangent (tan δ, at 10 GHz) of 0.0009, and substrate height of 0.508 mm. Southwest® end launcher (SEL) along with SIW-to-GCPW (Grounded Co-Planar Waveguide) transition has been used here to facilitate the measurement of antenna’s electrical and the radiation performance. The designed antenna’s impedance bandwidth and the 3 dB axial-ratio (AR) bandwidth is 9.5% and the 2.3%, respectively. It’s simulated and the measured peak gain, within working frequency band, is higher than 8.5dBic. The proposed antenna’s FBR is antenna is significantly lower than the conventional circularly-polarized antennas. Through comparative study, with work in open literature, it has been demonstrated that the designed antenna, based on proposed method, can a potential candidate for applicable in satellite and in the other spaceborne communication system’s module—at ground and in the space station.