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Summary In this article, a compact quad element coplanar waveguide (CPW) fed ultra‐wideband (UWB) multiple input multiple output (MIMO) antenna for future generation wireless communication system using a machine learning (ML) optimization approach is presented. The proposed antenna is used for 5G new radio (n46/n77/n47/n78/n48/n79), Wi‐Fi 5, Wi‐Fi 6, and dedicated short range communications (DSRC) services, vehicle to infrastructure (V2I), vehicle to vehicle (V2V), and vehicle to network (V2N) in the entire operating frequency band. It is operating from 3.2 to 11.85 GHz. The bandwidth is 8.65 GHz, and the percentage of impedance bandwidth is 115%. The comparative analysis between dual and quad elements are presented. It is optimized through the various ML model K‐nearest neighbor (KNN), extreme gradient boosting (XGB), artificial neural network (ANN), and random forest (RF). The KNN ML model achieved a higher accuracy of 93%, and it accurately predicted the S parameters of the suggested UWB antenna. The MIMO parameters are calculated and found within the acceptable limits. There is a strong correlation between the simulated and measured results. Hence, the suggested antenna is a suitable candidate for future wireless communication systems. [ABSTRACT FROM AUTHOR]

This work presents two Wilkinson power dividers (WPDs) using multi-layer pseudo coplanar waveguide (PCPW) structures. The PCPW-based WPDs were designed, implemented, and verified in a standard 180 nm CMOS process. The proposed PCPW features high slow-wave and low-loss performances compared to other common transmission lines. The two WPDs are based on the same PCPW structure parameters in terms of line width, spacing, and used metal layers. One WPD was realized in a straight PCPW-based layout, and the other WPD was realized in a meandered PCPW-based layout. Both the two WPDs worked up to V-band frequencies, as expected, which also demonstrates that the PCPW guiding structure is less susceptible to the effects of meanderings on the propagation constant and characteristic impedance. The meandered design shows that the measured insertion losses were about 5.1 dB, and its return losses were better than 17.5 dB at 60 GHz. In addition, its isolation, amplitude imbalance, and phase imbalance were 18.5 dB, 0.03 dB, and 0.4°, respectively. The core area was merely 0.2 mm × 0.23 mm, or 1.8 × 10−3λo2. [ABSTRACT FROM AUTHOR]

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Copyright of Micronanoelectronic Technology is the property of Micronanoelectronic Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper investigates the performance of coplanar waveguide (CPW) structures loaded with symmetric circular and polygonal split-ring resonators (SRRs) for microwave and RF applications, leveraging their unique electromagnetic properties. These properties make them suitable for metamaterials, sensors, filters, resonators, antennas, and communication systems. The objectives of this study are to analyze the impact of different SRR shapes on the transmission characteristics of CPWs and to explore their potential for realizing compact and efficient microwave components. The CPW-SRR structures are fabricated on a dielectric substrate, and their transmission properties and spectrogram are experimentally characterized in the frequency range of 4 GHz to 10 GHz with the rotation angles of the SRR gap. The simulation results demonstrate that the resonant frequencies and magnitude of the transmission coefficient of the CPW-SRR structures are influenced by the geometry of the SRR shapes and the rotation angles of the SRR gap, with certain shapes exhibiting enhanced performance characteristics compared to others. Moreover, the symmetric circular and polygonal SRRs offer design flexibility and enable the realization of miniaturized microwave components with improved performance metrics. Overall, this study provides valuable insights into the design and optimization of CPW-based microwave circuits utilizing symmetric SRR shapes, paving the way for advancements in the miniaturization and integration of RF systems. [ABSTRACT FROM AUTHOR]

This paper presents an ultrawideband dual circularly polarized (CP) rectenna for wireless energy harvesting (WEH) applications. It is mainly composed of a dual CP antenna and an ultrawideband rectifier. The receiving antenna is fed by a coplanar waveguide (CPW) and it has two input ports. The proposed ultrawideband rectifier has a two-cascaded voltage doubler configuration. This configuration means the proposed rectifier's input impedance has less sensitivity to frequency variation. Thus, a wide bandwidth can be achieved. For validation, a prototype is designed, fabricated and measured. The measured results show that the axial ratio (AR) bandwidth of the proposed rectenna is from 1.35 to 3.10 GHz (for AR <3 dB). In this frequency range, the rectenna's power conversion efficiency (PCE) is higher than 55%. These results indicate that the proposed rectenna is highly efficient and suitable for wideband high-efficiency WEH systems. [ABSTRACT FROM AUTHOR]

In this article, a novel coplanar waveguide (CPW) spiral cross resonators (SCRs) is introduced for creating a dual‐band balanced bandpass filter (BPF) with adjustable passbands. The resonant properties of the SCRs in both the differential mode (DM) and common mode (CM) are scrutinized. Furthermore, DM bisection offers two distinct parameters for internal coupling adjustment, enabling independent passband width control. A novel grounding wire feeding arrangement matches the external Q factor of the dual DM passbands. An additional stepped‐impedance short‐circuited conducting stub between resonators prevents excessive coupling while obtaining moderate bandwidths. Inherent CM suppression can be attained by distinguishing CM resonant frequencies distinct from the DM frequencies. To validate the design, a dual‐band balanced BPF designed and fabricated to operate at 2.42 and 5.2 GHz exhibits closely matching measured results compared to the simulated ones. [ABSTRACT FROM AUTHOR]

This work presents two Wilkinson power dividers (WPDs) using multi-layer pseudo coplanar waveguide (PCPW) structures. The PCPW-based WPDs were designed, implemented, and verified in a standard 180 nm CMOS process. The proposed PCPW features high slow-wave and low-loss performances compared to other common transmission lines. The two WPDs are based on the same PCPW structure parameters in terms of line width, spacing, and used metal layers. One WPD was realized in a straight PCPW-based layout, and the other WPD was realized in a meandered PCPW-based layout. Both the two WPDs worked up to V-band frequencies, as expected, which also demonstrates that the PCPW guiding structure is less susceptible to the effects of meanderings on the propagation constant and characteristic impedance. The meandered design shows that the measured insertion losses were about 5.1 dB, and its return losses were better than 17.5 dB at 60 GHz. In addition, its isolation, amplitude imbalance, and phase imbalance were 18.5 dB, 0.03 dB, and 0.4°, respectively. The core area was merely 0.2 mm × 0.23 mm, or 1.8 × 10−3λo2.

Flexible substrates are currently gaining attraction in the field of communication. Antenna designers working on thin flexible substrates extrapolate the techniques available for rigid substrate based designs. This eventually makes the design process inaccurate. To the best of our knowledge there is not much literature available that speaks about the design considerations on thin flexible substrates. The difference noticed between simulation and measurement results of a planar straight monopole antenna fabricated on a thin flexible substrate is the motivation for this work. The paper presents the outcome of an in-depth study carried out to get a better understanding of the predominant effect of dielectric constant, substrate thickness and conductor thickness on the performance of a Coplanar waveguide (CPW) transmission line designed on a thin flexible substrate. Based on the results of the exhaustive simulation studies, an accurate design equation is developed for the effective permittivity of thin substrates. This novel design approach is further extended to a conventional CPW fed straight monopole antenna designed on a thin flexible substrate with permittivity 3.5, loss tangent 0.027, height 130 µm and conductor thickness 0.035 mm. Good matching is obtained between simulation and measurement results, validating the proposed design approach. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of coplanar waveguide (CPW) structures loaded with symmetric circular and polygonal split-ring resonators (SRRs) for microwave and RF applications, leveraging their unique electromagnetic properties. These properties make them suitable for metamaterials, sensors, filters, resonators, antennas, and communication systems. The objectives of this study are to analyze the impact of different SRR shapes on the transmission characteristics of CPWs and to explore their potential for realizing compact and efficient microwave components. The CPW-SRR structures are fabricated on a dielectric substrate, and their transmission properties and spectrogram are experimentally characterized in the frequency range of 4 GHz to 10 GHz with the rotation angles of the SRR gap. The simulation results demonstrate that the resonant frequencies and magnitude of the transmission coefficient of the CPW-SRR structures are influenced by the geometry of the SRR shapes and the rotation angles of the SRR gap, with certain shapes exhibiting enhanced performance characteristics compared to others. Moreover, the symmetric circular and polygonal SRRs offer design flexibility and enable the realization of miniaturized microwave components with improved performance metrics. Overall, this study provides valuable insights into the design and optimization of CPW-based microwave circuits utilizing symmetric SRR shapes, paving the way for advancements in the miniaturization and integration of RF systems.

Proposed in this manuscript is a broadband bandpass filter (BPF) with dual in-band transmission zeros (TZs) and elongated stopband for application in ultra-wideband (UWB) networks. The basic structure is developed on the principle of broadside coupling of microstrip-to-coplanar waveguide (CPW). Semi-elliptical microstrips on the top are arranged in back-to-back manner and coupled to the open circuited CPW in the ground. The basic BPF is of 3rd order with good insertion/return loss. To this basic BPF structure multiple defected ground structures (DGS) in the shape of complimentary split ring resonator (CSRR) are appended to place dual Tzs within the passband and later dumbbell-shaped DGS are engraved in the CPW to widen the stopband. Also, an approximate equivalent lumped element circuit model is developed and its frequency characteristics matched against full-wave EM simulation. The proposed dual notched BPF is finally fabricated and is found to occupy a compact area of 13.6 × 6.75 mm2. [ABSTRACT FROM AUTHOR]

In this paper, a simple coplanar waveguide fed compact electrically small antenna for dual-band operations without the use of via is presented. The resonances of the structure are obtained by spiraling one of the ground planes of an open-ended CPW transmission line with a short length center feed. The proposed antenna has a geometrical dimension of 0.079λ01× 0.079λ01 mm2 (λ01 is the free space wavelength of first resonant frequency) with a small electrical size (ka) of 0.35. The experimental studies on the fabricated prototype of the proposed antenna show a 2:1 VSWR bandwidth up to 2.53% and 4.12% for 2.3 and 5.3 GHz, respectively. The simulated antenna reflection and radiation characteristics are demonstrated with physical measurements. [ABSTRACT FROM AUTHOR]

Abstract A broadband circularly polarized (CP) printed monopole antenna which fed by coplanar waveguide (CPW) is proposed in the paper. The structure of the novel antenna includes a quarter circular disc radiating monopole, a coupled circular patch, and a bent L-shaped microstrip stub line. The L-shaped microstrip stub line is used to widen the impedance bandwidth and generate a horizontal component of the electromagnetic wave. The adoption of the asymmetric ground coplanar waveguide structure with the single-feed technology and the coupled circular patch, simultaneously achieve wide impedance bandwidth and wide axial ratio (AR) bandwidth. The structure parameters and the surface current of the designed antenna are analysed. The simulation and the measurement are conducted, showing good characterizations of the designed antenna. The 10-dB impedance bandwidth is 7.57 GHz, the fractional bandwidth from 6.05 to 13.62 GHz is 76.9%, the 3-dB axial ratio bandwidth is 3.01 GHz, and the fractional bandwidth from 6.05 to 9.06 GHz is 39.8%. The antenna can generate right/left hand circularly polarized waves in the direction of ± z axis. The designed antenna has wide applications in the fields of Internet of Things (IoT), broadband dual-CP communication systems and polarization diversity systems, wireless personal area network and other advanced communication systems.

In superconducting quantum processors, the predictability of device parameters is of increasing importance as many laboratories scale up their systems to larger sizes in a 3-D-integrated architecture. In particular, the properties of superconducting resonators must be controlled well to ensure high-fidelity multiplexed readout of qubits. Here, we present a method, based on conformal mapping techniques, to predict a resonator's parameters directly from its 2-D cross-section, without computationally heavy and time-consuming 3-D simulation. We demonstrate the method's validity by comparing the calculated resonator frequency and coupling quality factor with those obtained through 3-D finite-element-method simulation and by measurement of 15 resonators in a flip-chip-integrated architecture. We achieve a discrepancy of less than 2% between designed and measured frequencies for 6-GHz resonators. We also propose a design method that reduces the sensitivity of the resonant frequency to variations in the interchip spacing.

In this paper, the laminated conductor technology is first introduced to planar-integrated transmission lines. The laminated conductor is composed of multilayers of metal and insulator, which has a lower conductor loss than a solid conductor. Based on the silicon-based micro electromechanical system technology, a laminated coplanar waveguide (CPW) with wide bandwidth and low loss is proposed, which uses a laminated conductor for signal lines and grounds. A laminated CPW and its transition are designed, fabricated, and measured. The simulation results show that the laminated CPW with many insulator layers has a low conductor loss. The measurement results illustrate that the average insertion loss of the laminated CPW is 0.65 dB from DC to 40 GHz, which is 44.4% smaller than that of the solid CPW. [ABSTRACT FROM AUTHOR]

A broadband circularly polarized (CP) printed monopole antenna which fed by coplanar waveguide (CPW) is proposed in the paper. The structure of the novel antenna includes a quarter circular disc radiating monopole, a coupled circular patch, and a bent L-shaped microstrip stub line. The L-shaped microstrip stub line is used to widen the impedance bandwidth and generate a horizontal component of the electromagnetic wave. The adoption of the asymmetric ground coplanar waveguide structure with the single-feed technology and the coupled circular patch, simultaneously achieve wide impedance bandwidth and wide axial ratio (AR) bandwidth. The structure parameters and the surface current of the designed antenna are analysed. The simulation and the measurement are conducted, showing good characterizations of the designed antenna. The 10-dB impedance bandwidth is 7.57 GHz, the fractional bandwidth from 6.05 to 13.62 GHz is 76.9%, the 3-dB axial ratio bandwidth is 3.01 GHz, and the fractional bandwidth from 6.05 to 9.06 GHz is 39.8%. The antenna can generate right/left hand circularly polarized waves in the direction of ± z axis. The designed antenna has wide applications in the fields of Internet of Things (IoT), broadband dual-CP communication systems and polarization diversity systems, wireless personal area network and other advanced communication systems. [ABSTRACT FROM AUTHOR]

An innovative magnetodielectric nanocomposite antenna is proposed for enhancing antenna parameters of monopole radiator by coplanar waveguide (CPW) feeding. A magnetodielectric nanocomposite radiator works in triband that covers the frequency band in WLAN, WiMAX and 5G. This compact antenna incorporates three radiating elements, whose total width is only 35% width of signal strip and length of the longer monopole is only 0.18 wavelength at its resonance frequency. To obtain a good impedance bandwidth for the triple band operation, two narrow rectangular patches (4 × 2 mm2, 4.5 × 1.5 mm2) are embedded in the two radiating elements of antenna. Carbon-coated cobalt (CCo) in coalesce with polyaniline (PANI) results in a magnetodielectric polymer-based nanocomposite. To enhance the antenna parameter the 'L' shaped slot upright to CPW ground, which is filled with PANI/CCo magnetodielectric nanocomposite. The resulting antenna produce good 10-dB impedance bandwidth of 0.43 GHz (2.30–2.73 GHz), 0.41 GHz (3.35–3.76 GHz) and 0.94 GHz (5.02–5.96 GHz) for entire WLAN/WiMAX bands are covered, 2.3–2.4 GHz inclusively 2.5–2.69 GHz 5G bands and 82% band width of 3.3–3.8 GHz 5G band are also included along with good radiation characteristics for entire triple band. [ABSTRACT FROM AUTHOR]

In this letter, a terahertz monolithic integrated planar band‐pass filter based on coplanar waveguide (CPW) resonators has been proposed. By adopting the feeding line in form of a slotline, the need for air‐bridges in traditional CPW filters is eliminated, achieving good integrability and reducing fabrication difficulty. To further improve the filtering performance, the defected ground structure is used in the design, introducing a finite transmission zero at the lower sideband. The filter is manufactured on the semi‐insulation silicon carbide (SiC) substrate, to fit the existing advanced GaN‐on‐SiC monolithic integration system. Measurement reveals the fractional band‐width of 5.7% at the center frequency of 279 GHz, with an insertion loss of 5.1 dB. With a volume of 500 × 400 × 50 μm (0.45 × 0.36 × 0.045 λ0), the proposed filter improves the performance of the planar filter operating at the terahertz band effectively. [ABSTRACT FROM AUTHOR]

A single-layer multimode metasurface antenna is proposed with a coplanar waveguide (CPW)-fed aperture. The ultra-wideband (UWB) performance is implemented based on a three-step evolution process with the aid of characteristic mode analysis (CMA). Considering the efficient excitation with a fixed feeding structure, the metasurface modal current variation at different frequencies is analyzed and optimized, in addition to that at the resonant frequency. Correspondingly, the metasurface is firstly designed utilizing an array of 4 × 4 patches. Then, the 1 × 3 and the 1 × 1 parasitic patch arrays are located near the edge patches. Finally, every patch is split into two by a center slot along the current distribution of the required polarization. Four resonant modes of the metasurface become more desirable step by step and can be efficiently excited over the entire band. To enhance the impedance matching level, a pair of 5-stage gradient transitions are added to the CPW-fed slot. The slot mode combined with the four modes further improves the bandwidth. The experimental results demonstrate that the proposed antenna exhibits a 3 dB gain bandwidth of over 74% (4.0–8.7 GHz) with a peak gain of 8.2 dBi. The overall dimensions of the prototype are 1.40λ0 × 1.40λ0 × 0.075λ0 (λ0 is the free-space wavelength at 6 GHz). [ABSTRACT FROM AUTHOR]

This paper presents a single-frequency reflective-mode phase-variation microwave sensor devoted to the dielectric characterization of materials. The device is implemented in coplanar waveguide (CPW) technology and consists of two parts: (i) the sensing region, a step-impedance resonator (SIR) as termination of a CPW transmission line, and (ii) the design region, a cascade of high/low impedance quarter-wavelength inverters, used to boost up the sensitivity. By placing the so-called material under test (MUT) on top of the sensing region, the capacitance of the SIR is altered due to the effects of the dielectric constant of the MUT. This modifies the phase of the reflection coefficient seen from the input port, the output variable. From a circuit analysis, it is demonstrated that the sensitivity for small perturbations in the vicinity of the dielectric constant of a reference (REF) material can be optimized by setting the operation frequency of the sensor to the resonance frequency of the SIR loaded with such REF material. The maximum sensitivity in one of the reported sensors is as high as 66.5°, and the main figure of merit, defined as the ratio between the maximum sensitivity and the area of the sensing region expressed in terms of the squared guided wavelength, is $\text {FoM} = 3643^{\circ }/\lambda ^{2}$ . Such figure of merit represents a significant improvement as compared to the one of the equivalent sensor implemented by means of an open-ended quarter-wavelength sensing line. Such equivalence between the semi-lumped element (i.e., SIR-based) sensor and the fully distributed counterpart is also analyzed in the paper.

In this paper, a coplanar waveguide (CPW) fed slot antenna using fractal shaped isosceles trapezoidal corrugations is designed and presented for Ultra-Wideband (UWB) applications. The proposed antenna is formed by a regular hexagonal patch fed through a CPW feed line and radiates amidst a notched wide hexagonal slot. The edge of the wide slot is shaped by a fractal structure that is formed by five trapezoidal notches. The antenna is printed on RO4350B substrate having a compact size of 0.305λ0 × 0.313λ0 × 0.012λ0 at 2.35 GHz. Good agreement is registered between the experimental results of the fabricated prototype and the calculated ones. By using an Agilent 8722ES vector network analyzer, the fabricated prototype confirms that the antenna has an excellent matching impedance over the bandwidth 2.35-10.65 GHz (127%) which covers the entire UWB band. Furthermore, good radiation performances are measured in an anechoic chamber. Consistent radiation patterns with a reasonable peak gain are measured over the entire working bandwidth. Therefore, the designed structure may be worthy considered for different wireless communications systems. [ABSTRACT FROM AUTHOR]

A printed U-shaped coplanar waveguide fed (CPW) ultra-wideband (UWB) antenna is designed, fabricated, and measured in this paper for ground penetrating (GPR) applications. To enhance the working bandwidth, a set of cutoffs was introduced in different parts of the antenna. The antenna was printed on the FR4-epoxy substrate in a compact size of 0.252λ0×0.3λ0×0.015λ0 at 3 GHz. The calculated results were validated by realizing and measuring a prototype. Experimental demonstrations were done with the R& S®ZNB Vector Network Analyzer, which indicates that the antenna's working bandwidth extends from 3.09 GHz to 11.07 GHz (112.71%). Additionally, the antenna's radiation patterns were measured in an isolated anechoic chamber, which shows that the proposed antenna has omni-directional radiation patterns. Moreover, acceptable gain antenna values ranging between 1.74 and 7.04 dBi and high values of radiation efficiency of more than 80% were achieved over the whole working bandwidth. Besides, the antenna presents a stable group delay with a linear phase of S21 through the UWB frequency band. To prove the efficiency of the fabricated antenna for GPR applications, the operation of the antenna was experimentally tested in a sandy soil box. The obtained results show that the proposed antenna could be a good candidate for GPR applications.

A compact coplanar waveguide-fed triple-band multiple input multiple output (MIMO) antenna is designed based on flexible substrate named liquid crystal polymer in this work. The proposed antenna comprises two antenna elements placed side by side. By adding a double Y-shaped branch between two antenna elements, good isolation is achieved successfully, which is better than 21 dB. According to the measured results, it can operate bandwidth covering 2.263–2.925, 3.063–4.5 and 4.588–7.25 GHz, meeting the radio spectrum, including 5G, WLAN and WiMAX. Moreover, the proposed antenna also has virous suitable characteristics including envelope correlation coefficient (<0.01), diversity gain (>9.99), channel capacity loss (<0.4 bits/s/Hz), the difference of mean effective gain (<0.15 dB) and total active reflection coefficient (<−10 dB). The bending test and the effect of human body have also been analyzed. The actual measurement indicates that the presented MIMO antenna is desirable for integration in wearable 5G/WLAN/WiMAX devices. [ABSTRACT FROM AUTHOR]

A W-band slot array antenna based on a substrate integrated waveguide (SIW) for microwave power transmission (MPT) is proposed in this paper. By size optimization, the transition from the rectifier element to the antenna is limited to a small size. It realizes a compact arrangement of the radiating slots, which not only improves the aperture efficiency of the antenna but also makes it easy to integrate into a large-scale array. For antenna testing, a coplanar waveguide–SIW–rectangular waveguide transition structure is added at the end of the antenna, and an antenna with this transition structure is processed by PCB printing technology and measured. The measured reflection coefficient is less than −10 dB at 90–96 GHz, the aperture efficiency is greater than 60% at 93.5–94.5 GHz, the maximum gain is 13.2 dB at 93.5 GHz, and the aperture efficiency is 79%. The test results of the antenna show that the antenna has a good performance and can be applied to the MPT system as a rectenna. [ABSTRACT FROM AUTHOR]

To integrate different wireless applications into one device, multi-frequency microstrip patch antennas are the best solution to maintain the overall device size. A multiband patch antenna charged with a planar metamaterial unit cell is proposed in this work. The metamaterial unit cell is composed of an interdigital capacitor with near zero-index metamaterial (NZIM), the proposed method is used to recover the effective properties, i.e. impedance, refractive index, permittivity, and permeability of the unit cell. This type of antenna consists of a coplanar waveguide (CPW) and an interdigital capacitor patch. The insertion of a slot around the proposed unit cell allows producing new bands different from the first ones, for wireless communication systems for different interdigitated finger lengths, with and without a gap. The first part deals with the antenna without a gap, it provides a single frequency at 𝒇𝒓𝟏 = 𝟓. 𝟓𝑮𝑯𝒛 covering an absolute bandwidth of 𝟓𝟕𝟔𝑴𝑯𝒛 ( 𝟓. 𝟏𝟔𝟖𝟏 to𝟓. 𝟓𝟏𝟕𝟐𝑮𝑯𝒛). In the second part, where a gap is considered, the antenna can provide frequency bands, 𝒇𝒓𝟐 = 𝟒. 𝟎𝟑𝑮𝑯𝒛, 𝒇𝒓𝟑 = 𝟔. 𝟒𝟑𝑮𝑯𝒛, with 𝟐𝟓𝟕𝑴𝑯𝒛 (𝟑. 𝟖𝟗𝟓𝑮𝑯𝒛 to𝟒. 𝟏𝟓𝟐𝑮𝑯𝒛), and 85MHz (6.387GHz to 6.472GHz), bandwidths respectively, with low return loss and uniform radiation patterns. The peak simulated gains of 𝟒. 𝟗𝟓 𝒅𝑩, 𝟑. 𝟓𝟔 𝒅𝑩, and𝟑. 𝟖𝟔𝒅𝑩, at𝟓. 𝟒𝟓𝑮𝑯𝒛,𝟒. 𝟎𝟑𝑮𝑯𝒛, and 𝟔. 𝟒𝟑𝑮𝑯𝒛 consecutively. By adjusting certain correlated parameters, the operating bands of the presented antenna can be modified individually, as a result, we achieve systematic minimization of the electrical size of the antenna. The antenna structure is simulated and investigated numerically by using the CST Microwave Studio, and the obtained results are compared and validated with HFSS. The structure was fabricated and analyzed using a Keysight PNA network analyzer from 𝟏𝟎𝑴𝑯𝒛 to 𝟒𝟑. 𝟓 𝑮𝑯𝒛 to show that it performs well and meets the requirements for multiband applications. [ABSTRACT FROM AUTHOR]

A wideband biocompatible implanted antenna is designed for wireless biotelemetry applications at industrial, scientific and medical (ISM) band (2.4-2.48 GHz). The antenna is fed by a conductor backed coplanar waveguide (CB-CPW) structure and two H-shaped slots are etched side by side on the patch of the antenna to create a resonance at the desired frequency. The experimental and simulation measurements are performed by using skin, fat and muscle tissue layers. The impedance bandwidth (S_11≤-10 dB) of the proposed antenna is measured as 0.406 GHz (2.272 - 2.678 GHz), when the fabricated antenna is implanted inside a three-layered human body mimicking gel. By using the advantage of having a wide bandwidth, the designed antenna is analyzed inside different tissue types and tissue thicknesses. For every obtained simulation and experimental result, it is observed that the antenna always covers the ISM band, which is the most significant contribution of this study. The size of the implantable antenna is 16×13×1.93 mm3, where both sides of the antenna is covered by a superstrate material to extend the life of the antenna inside the tissue.

In this article, a flexible, stretchable, and dynamically tunable attenuator based on coplanar waveguide (CPW) and graphene is proposed. Soft silicone elastomer and serpentine metal structure are used to realize the flexible, stretchable, and biocompatible characteristics of the CPW. A graphene sandwich structure (GSS) is placed on the upper surface of the CPW to dissipate the electromagnetic wave, achieving the dynamically adjustable characteristics of the stretchable attenuator. When the surface impedance of the GSS is tuned by applying a proper bias voltage, the simulated and measured results reveal that the attenuation tuning range is dynamically tuned from 4–11 dB with a low reflection below −10 dB. In addition, the fabricated attenuator is simultaneously optimized to work at conditions of the normal state, 180° bending and 130% stretching, with acceptable changes between insertion loss and return loss up to 6 GHz. The attenuator covers the medical frequency band of 2.4–2.483 GHz and the 5th generation (5G) communication frequency band of 3.5–3.8 GHz, which demonstrates that the attenuator has potential applications in stretchable electronic systems. [ABSTRACT FROM AUTHOR]

This paper presents a one-port reflective-mode phase-variation microwave sensor consisting of a coplanar waveguide (CPW) transmission line terminated with a grounded open complementary split ring resonator (OCSRR). The sensor is useful for measuring the dielectric constant of the so-called material under test (MUT), which should be placed in contact with the OCSRR, the sensitive element. The output variable is the phase of the reflection coefficient. Design guidelines for the implementation of highly sensitive sensors are derived in the paper, and validated through simulation and experiment. As compared to other reflective mode phase-variation sensors based on open-ended sensing lines, the designed and fabricated devices exhibit a very small sensitive region by virtue of the use of an electrically small resonant element, the OCSRR. The relevant figure of merit, defined as the ratio between the maximum sensitivity and the size of the sensing area (expressed in terms of the squared wavelength), is as high as FoM = 5643°/λ2 in one of the reported prototypes. Moreover, the paper analyzes the effects of losses. From this study, it is concluded that MUT losses do not significantly affect the output variable, provided losses are small. It is also demonstrated that the sensor is useful to estimate the loss tangent of the considered MUT samples.

In this article, a co‐planar waveguide‐fed ultra‐wideband (UWB) multiple‐input multiple‐output flexible antenna with dual band‐notched characteristics on liquid crystal polymer substrate with high isolation for wireless body area network application is designed and fabricated. Two fan‐shaped monopole UWB antenna elements are designed and placed vertically, with tampered feeder, asymmetrical ground plane and two C‐shaped slots on the radiation patch. The measured working bandwidth can reach 2.63–11.6 GHz and the rejection bands are 3.25–4.36 and 5.41–6 GHz. The port isolation (S21) is better than −22 dB. When the bending radius is 35 and 45 mm, the antenna is measured for flexibility. In addition, the antenna is placed on human tissue to test its performance. All the results show that it has good radiation, high isolation and flexibility, and has broad application prospects in the wearable field. [ABSTRACT FROM AUTHOR]

A compact conformal coplanar waveguide-fed (CCF) ultra-wideband (UWB) monopole antenna with dual notched bands at 3.25-3.85 GHz and 5.25-5.85 GHz for worldwide interoperability for microwave access (WiMAX) applications is presented in this paper. The evolution of the proposed antenna structure is presented in a stepwise manner with the incorporation of a parasitic element and a PIN diode. In the proposed structure, the bandwidth enhancement and band notch are realized by an asymmetric design, which has two I-shaped stub lines parallel to the feed line and two semicircles on both sides of the feed line. The notch is achieved by applying the parasitic element parallel to the patch and placing a PIN diode between the parasitic element and the antenna patch. The volumetric size of the antenna is 24×22×0.035 mm3. The proposed structure attains an operating band (VSWR ≤ 2) ranging from 3.1 to 10.6 GHz with a gain close to 3.95 dBi, along with significant efficiency and symmetrical radiation patterns. Parasitic elements are used to improve directivity or gain and reduce the back lobe. By choosing the parasitic elements, different resonant modes can be excited nearby each other, which can provide a wider bandwidth. The proposed antenna is low profile and is designed to be used as a transceiver in UWB communication for WiMAX applications. [ABSTRACT FROM AUTHOR]

In this paper, for the first time, effects of external electromagnetic fields on a coplanar waveguide (CPW) are numerically studied by means of the method of finite elements. Two CPW lines with different geometry and dielectric substrate permittivity are considered. Both lines have characteristic impedance of 50 Ω. Induced electric and magnetic fields on the two CPW lines are analyzed by illuminating the structure with a plane wave. The uniform plane wave with fixed frequency at 3 GHz is considered as the incident field. The influences of the incidence angle and dielectric substrate permittivity are investigated. For this purpose, two incidence planes are considered and, for each case, two polarizations, parallel and perpendicular, for incidence electric field relative to incidence planes are studied. According to the results, for the two CPW lines terminated with their characteristic impedance at both ends and the incident plane wave with electric-field intensity of 1 V/m at f = 3 GHz with incidence angles of 22.5˚ and 45˚, maximum peaks of the induced field occur and also, depending on the incidence plane, incidence angle and E-field polarization, even or odd quasi-TEM mode of the CPW line can be propagated.

Abstract An efficient and compact dual bandpass filter having single narrow rejection band between S-band and C-band using CPW arrangement is proposed. The half wavelength square resonator is used in ground surface to eliminate certain frequency bands. The transmission zero of rejection band is restricted by modifying the dimension of the resonator. The CPW-based DB-BPF is simulated and tested with its equivalent prototype. This work emphasizes DB-BPF with square resonator coupling constructed on CPW process. An innovative integration of circular resonator incorporated with inter-digital line coupling in the top surface of the substrate and square resonator at the bottom surface of the substrate produces wide band and narrow stop band, respectively. The DB-BPF has remarkable bandwidth from 2 to 3.8 GHz and 4.3 to 7.8 GHz as S-band and C-band, respectively. Hence, the overall bandwidth of the filter is 5.3 GHz (1.8 GHz and 3.5 GHz). The filter performances are evaluated and analyzed through the factors like S-parameters, Q-factor and group delay. The overall dimension of DB-BPF is achieved to be (39 × 4.5 × 1.6) mm3, which is very much compact in dimension. The filter characteristics show the return loss of − 35.2 dB and insertion loss of − 1.2 dB which are validated by measured results.

An investigation on antenna solutions for expendable origami paper flapping robots is presented. An origami flapping robotic bird that can be produced using standard A4 paper is employed. Antennas resonating at the two commonly used frequency bands, 2.4 GHz and 5.2 GHz, are designed for the limited space available on the folded origami structure. Two developments of the same dual-band monopole antenna are discussed. The first antenna is located on the robot's spine and the second on its tail. A space diversity configuration is also studied. The antennas are printed directly onto a photo paper substrate and then folded into an origami robotic crane's body structure. An ordinary desktop inkjet printer fitted with silver nanoparticle conductive ink cartridges has been employed. CST Microwave StudioTM has been used to design the antennas. A good agreement between the measured and simulated S11 results is achieved with a reasonable -10dB impedance bandwidth realized in the three cases studied. The radiation patterns are omnidirectional in the XZ plane which is desirable for the specific application. The diversity configuration has a mutual coupling of

A single-layer multimode metasurface antenna is proposed with a coplanar waveguide (CPW)-fed aperture. The ultra-wideband (UWB) performance is implemented based on a three-step evolution process with the aid of characteristic mode analysis (CMA). Considering the efficient excitation with a fixed feeding structure, the metasurface modal current variation at different frequencies is analyzed and optimized, in addition to that at the resonant frequency. Correspondingly, the metasurface is firstly designed utilizing an array of 4 × 4 patches. Then, the 1 × 3 and the 1 × 1 parasitic patch arrays are located near the edge patches. Finally, every patch is split into two by a center slot along the current distribution of the required polarization. Four resonant modes of the metasurface become more desirable step by step and can be efficiently excited over the entire band. To enhance the impedance matching level, a pair of 5-stage gradient transitions are added to the CPW-fed slot. The slot mode combined with the four modes further improves the bandwidth. The experimental results demonstrate that the proposed antenna exhibits a 3 dB gain bandwidth of over 74% (4.0–8.7 GHz) with a peak gain of 8.2 dBi. The overall dimensions of the prototype are 1.40λ0 × 1.40λ0 × 0.075λ0 (λ0 is the free-space wavelength at 6 GHz).

An extremely compact antenna design for Ultra-wideband (UWB) application has been presented in this paper that successfully displays band-notch characteristics at the WLAN band. The design consists of a truncated radiator supplied by a 50 Ω Coplanar Waveguide (CPW) feedline structure. The antenna has been mounted on a FR4 substrate, and its ground plane has been etched with an inverted-L slot responsible for frequency-notch characteristics at the WLAN band (5.15-5.825 GHz). The ground plane has been defected by engraving a rectangular slot in the ground plane for improving the impedance bandwidth. The antenna has a profile size of 19x9x1.6 mm³. The performance of the antenna has also been compared with another design having twice the dimensions of the proposed structure (30x26x1.6 mm³). [ABSTRACT FROM AUTHOR]

A single-layered slot antenna system working at 5.8 GHz Industrial, Scientific and Medical (ISM) band is proposed for in-band full duplex (IBFD) operation applications without the use of a coupler. First, high isolation is achieved by strong separation of even- and odd-mode feeds. The microstrip-coupled coplanar waveguide (CPW) is used at Port 1 (TX port) to excite a stepped-slot antenna in the CPW odd mode. On the opposite side, a microstrip T-junction power divider is employed at Port 2 (RX port) to feed two offset-fed stepped-slot antennas in even mode. Second, isolation is further improved by 30 dB by using a lumped capacitor at the termination of the CPW. The measured isolation between the two ports is about 50 dB across the bandwidth. The measured −10 dB bandwidth of Port 1 is 0.49 GHz (8.5%), while that of Port 2 is 1.06 GHz (18.3%). The gains of TX and RX antennas are 5.4 and 5.8 dBi at 5.8 GHz. The proposed antenna can also be deployed as a dual-polarized antenna. Mathematical analysis and equivalent transmission line circuit models are provided to give physical insight into the working principals of the antenna with validation from ANSYS HFSS simulation. [ABSTRACT FROM AUTHOR]