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This paper presents, for the first time, a tunable left handed coplanar waveguide zeroth-order resonator on a ferrite substrate. Analysis and design procedures of the proposed resonator are introduced. The proposed resonator is designed to be tuned over the frequency band from 3 to 4.85 GHz with lower than 3-dB insertion loss and better than 10-dB return loss. The dimensions of the proposed resonator are 8.3 x 20 mm. The advantages of the proposed resonator are its tuning capability in addition to its compact size. Index Terms--Ferrite, left-handed media, metamaterials, resonator.

A novel coplanar waveguide ferrite-coupled line (CPW FCL) is presented and numerically verified for the first time. The proposed CPW FCL exhibits a low insertion loss for both even and odd mode excitations, equal power division for single power excitation with both isolation, and return loss better than 10 dB over the whole operating bandwidth, and 20 dB in the best cases. The coupler has a much wider operation bandwidth compared to any other configurations reported to date. In addition, the CPW FCL demonstrates better phase flatness within the operating bandwidth compared to microstrip FCL. Index Terms--Coplanar waveguide (CPW), ferrite, ferrite coupled lines (FCLs), nonreciprocal devices.

A set of novel left-handed LH) basic block monolithic-microwave integrated-circuit (MMIC) components (transmission line, open and short stubs) are presented with applications to the RF/microwave filter and power divider. These new open and short LH MMIC resonators have compact sizes of 0.11 and 0.22 [mm.sup.2], respectively. The prototypes of an LH bandpass filter and LH power divider constructed from these basic components have been designed, fabricated, and characterized. The LH filter consisting of an LH transmission line and four LH open resonators exhibits transmission zeros at both sides of the passband from 1.02 to 1.42 GHz with 33.3% fractional bandwidth. The LH power divider including two LH branches shows equal power split from 2.8 to 3.72 GHz. The filter and power divider benefit from the miniaturized LH MMIC components and have compact sizes of 2.85 and 2.3 [mm.sup.2], respectively. Loss issues of these LH structures and, more importantly, the effect of skin depth at low frequency are investigated. Full-wave simulations for conductor thicknesses of 0.2, 1.4, and 5 [micro]m are presented for the proposed LH MMIC components and circuits. There is a good agreement between the full-wave simulations, equivalent-circuit model, and measurement results with 1.4-[micro]m metal thickness demonstrating the effectiveness of the models. Index Terms--Bandpass filter, left-handed (LH) metamaterial, power divider, resonators.

A high tangential signal sensitivity (TSS) zero-bias GaAs planar doped barrier (PDB) diode for microwave and millimeter-wave power detection applications is presented. The fabricated PDB diodes have shown 4 dB better TSS at 35 GHz than that of reported devices, considerably increasing the minimum detectable power and widening the dynamic range. The high TSS was obtained by optimizing the PDB layer structures, namely, the [sigma]-doped [p.sup.++] layer and the two intrinsic layers, and by employing ion bombardment to better define the device and reduce parasitic effects. The isolation properties of ion bombarded epitaxial layers on GaAs substrates were examined and optimized to have a sheet resistivity of [l0.sup.8] [ohm]/sq. The temperature dependence of the barrier height of the PDB diode has been investigated experimentally, showing positive temperature coefficient and, hence, better thermal stability. We have also defined the critical barrier height and derived its analytical expression, which gives the theoretically lowest possible barrier height of a PDB diode. Index Terms--Ion bombardment, planar doped barrier (PDB) diodes power detectors and sensors, tangential signal sensitivity (TSS).

Current artificial magnetic conductor (AMC) designs use metallic patterns on rigid substrates and focus on shapes and sizes of AMC structures, rather than on material performance, which has hindered operation bandwidth and design flexibility. Here, we introduce printed graphene AMC-based broadband and flexible microwave radar absorbers, which not only redirect but also absorb the incident wave so to broaden the operation bandwidth. Contrasting to other reported works, the phase characteristics of the AMCs are realized through the control of the surface resistance provided by printed graphene laminates. We produced a variety of AMC structures, composed of printed graphene circular ring arrays with exactly the same shape and size, but different sheet resistances. By carefully designing the sheet resistance of printed graphene laminates, the optimized anti-phase reflection cancellation between AMCs can be achieved. With printed graphene AMCs and flexible dielectric substrate, the absorber presented in this work has a broadband effective absorption (above 90% absorptivity) from 7.58 GHz to 18, is polarization insensitive under normal incident, and can work at relatively wide incident angles. Furthermore, this absorber is capable of bending easily with notable performance, which makes it ideal for applications with irregular and uneven shapes. [ABSTRACT FROM AUTHOR]

This paper proposes an accurate model for yarn-based embroidered coil antenna used in Near Field Communication (NFC) applications. Traditionally, the inductance of a coil-shaped antenna is calculated using the Wheeler’s equation, while accurate enough for metallic coil geometries, the results from Wheeler’s equation have more than 20% errors when being applied to yarn-based embroidered antennas. We have discovered that this discrepancy is related to the parasitic capacitance, which is caused by the subtle gaps along twisted fibers. Experiments demonstrate that the parasitic capacitance has significant impact on the overall performances of the coil antenna. In this paper, an equivalent model for yarn-based coils is proposed to take into account of the parasitic capacitance and antenna geometrical characteristics. Compared with traditional Wheeler’s equation, the inductance calculated from this proposed model is within 5% from the measured value. Additionally, the electromagnetic performance of the embroidered coil is resilient to mechanical deformation. When being used as a coupling antenna, it can harvest energy and power-up the NFC-based platform for body-area-network applications. [ABSTRACT FROM AUTHOR]

This paper proposes a signal feedback interference topology to control the characteristics of a coupled line bandpass filter. Control is carried out by varying the ratio of the transmission line parameters of the forward and the feedback couplers. The topology produces a compact filter that does not require a complicated design or fabrication. The results of the insertion and return losses show that the feedback‐controlled design has desirable features in terms of the design frequency, fractional bandwidth, stopband rejection level, roll‐off rate and insertion loss. The test results of the fabricated prototype achieved good agreement with the simulation results of the ideal transmission line design model. Several microwave, modern wireless and mobile/satellite communication systems may benefit from such a filter design due to its compactness and flexibility. [ABSTRACT FROM AUTHOR]

This paper presents high‐power broadband graphene non‐Foster circuit (NFC) enabled Class‐J GaN HEMT power amplifier (PA). A graphene resonant‐tunneling diode (RTD) NFC is proposed to provide negative differential resistance characteristics and to create an effective negative capacitance. The NFC is integrated in the input matching network of the Class‐J GaN HEMT PA to cancel out the transistor input parasitic capacitance so as to enhance PA bandwidth, efficiency, output power, and gain. The PA design is based on Cree's packaged GaN HEMT CGHV40030F biased with drain supply voltage of 50 V at quiescent drain‐to‐source current of 44 mA. The PA operates from 3.4 to 4.0 GHz with center frequency of 3.7 GHz. The effective negative capacitance of the NFC from 3.4 to 4.0 GHz stands at −3.3 to −6.0 pF. An effective capacitance of −3.7 pF has been obtained at 3.7 GHz. The PA has small signal gain of 16.1 dB at 3.7 GHz. Large signal simulation input power sweep from 1 to 33 dBm at 3.7 GHz, indicates that the PA has 57.8% drain efficiency, 54.7% power added efficiency (PAE), 44.6 dBm (28.8 W) output power and 11.6 dB transducer power gain at input power of 33 dBm. [ABSTRACT FROM AUTHOR]

This paper presents analysis and experimental measurements of CPW and microstrip compact monopole antennas loaded with resonator circuits inspired from simplified half-mode composite right / left-handed unit cell. The antennas were designed to have a typical omnidirectional radiation pattern. The CPW fed dual-band antenna resonates at 2.4 and 5.8 GHz, respectively. The antenna size is 20 × 30 mm2 and the radiator patch is only 25% at 2.4 GHz and 60% 5.8 GHz in comparison with a conventional patch antenna. The microstrip triple-band antenna covers the frequency bands from 2 to 2.4 GHz, 5.4 to 6 GHz and 6.8 to 8 GHz. The antenna size is 28 × 25 mm2 which is less than 25% at lower frequency band compared to the size of the conventional patch antenna. Detailed theoretical and full-wave analysis is presented and experimental results demonstrate a good agreement between the measured and the simulated. The suggested antennas can be employed for compact size and multi-band functionalities in wireless applications. The loading technique can be adapted for more frequency bands. [ABSTRACT FROM AUTHOR]

A quad band antenna with good gain and omni-directional pattern is proposed in this paper. The antenna design is based on loading a conventional monopole antenna by three different resonators. The resonators are inspired from the shunt branch of composite right-/left-handed cell. The resonators have a simple structure and compact size. The control of the frequency bands can be achieved arbitrarily and hence the suggested design methodology can be generalized to any required bands. The fabricated antenna prototype is operating at 2.6, 3.35, 5.15, and 6.1 GHz with bandwidth wider than 100 MHz for each band. The antenna's operating principle and design procedures with the aid of electromagnetic full wave simulation are presented. Finally, the experimental results exhibit good agreement with the simulated ones which confirm the proposed designed methodology. The proposed monopole antenna has a patch size of 13.5 mm × 6.5 mm and the whole antenna size (including the feed line) is 35 mm × 32 mm. Compared to conventional single-band microstrip patch radiator size, the proposed quad band radiator has the size of 9, 15, 37.5, and 72.5% at relevant frequency bands. [ABSTRACT FROM AUTHOR]

The design and analysis of meta-material inspired loaded monopole antenna for multiband operation are reported. The proposed antenna consists of multi resonators inspired from half mode composite right/left handed cells, which has a simple structure, compact size, and provides multiband functionalities. As a proof of concept, a triple band antenna covering all possible WiMAX operating bands, has been designed, fabricated, and characterized. The hosting monopole patch itself generates resonance for 3.3–3.8 GHz band, whereas the loaded metamaterial cells add extra resonance frequencies. The loading of two resonator cells introduces two extra resonances for 2.5–2.7 GHz and 5.3–5.9 GHz bands, respectively. The antenna's operating principle and design procedures with the aid of electromagnetic full wave simulation and experimental measurements are presented. The antenna has good omnidirectional patterns at all three bands. The monopole patch size is 13.5 × 6.5 mm2 and the whole antenna size (including the feed line) is 35 × 32 mm2. Compared with conventional single band microstrip patch radiator, the radiator size of this antenna is only 8.5% at 2.5 GHz, 17% at 3.5 GHz, and 37% at 5.5 GHz. [ABSTRACT FROM PUBLISHER]

ABSTRACT This article presents a new compact asymmetric coplanar strip -fed UWB MIMO antenna. The UWB MIMO antenna consists of two identical elements which have quarter elliptical ring radiating element with asymmetric coplanar strip-fed. By designing the antenna using asymmetric coplanar strip-fed, the antenna size can be reduced (its size is only 6 × 2.6 cm2). The distance between the two antenna elements equals 0.37 λ0-The single antenna element is operated at frequencies from 3.1 GHz to 10.6 GHz with reflection coefficient lower than −10 dB. In addition, the designed antenna elements have less than 15 dB coupling isolation between the two input ports. The diversity performance between two antenna elements such as envelope correlation coefficient and diversity gain are investigated and they are within their allowed limits. This analysis confirms that the designed antenna is suitable for portable UWB MIMO applications. The proposed antenna is designed; simulated and measured. There is a good agreement between the simulated and measured results. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:31-36, 2017 [ABSTRACT FROM AUTHOR]

Covid-19 has demonstrated how vulnerable our society remains when it comes to managing a pandemic. There is an urgent need to develop and evaluate new technologies, materials, and methods for rapid measurement and continuous monitoring of body temperature, and accurate detection of elevated body temperature as a symptom of conditions which may lead to a pandemic. [ABSTRACT FROM AUTHOR]

A wideband CMOS LC tank voltage-controlled oscillator (VCO) with low phase noise variations and a linearized gain has been designed using a new binary-weighted switched-capacitor and digitally-controlled varactor bank. The novel design has the advantages of more linear VCO frequency tuning, lower phase noise and reduced gain to variations in supply voltage. The proposed VCO has been designed using UMC 90-nm, 6-metal CMOS technology and features phase noise variation of less than 4.9 dBc/Hz. The VCO operates from 3.45 to 6.55 GHz, with phase noise of -133.4 dBc/Hz at a 1 MHz offset, a figure of merit (FoM) of -203.3 dBc/Hz, less than 41 dBm spurious harmonics, and a total VCO core current consumption of 1.18 mA from a 3.3 V voltage supply. To the authors' knowledge, this is the lowest phase noise variation ever reported. [ABSTRACT FROM AUTHOR]

This letter presents a novel low phase noise free-running oscillator based on a high selectivity bandpass filter (BPF) using a composite right/left-handed transmission line (CRLH TL). The oscillator is designed at the spectrum-based quality factor (Qs) peak frequency to achieve low phase noise performance. Ata center frequency of 2.05 GHz, the oscillator demonstrates, experimentally, a phase noise of $-$150.4 dBc/Hz at 1 MHz frequency, offset with a figure of merit(FOM) of $-$207.2 dBc/Hz, less than $-$32 dBm spurious harmonics, and total oscillator power consumption of 6.1 mW from a 2 V supply voltage. [ABSTRACT FROM PUBLISHER]

A novel ferrite nonreciprocal left-handed (LH) transmission line is presented. The proposed structure is composed of a coplanar waveguide over a ferrite substrate, horizontally magnetized and periodically loaded with only shunt inductors. The line has a nonreciprocal LH propagation with transmission level better than -5 dB with isolation level up to 20 dB over a moderate bandwidth. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2810–2814, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22848 [ABSTRACT FROM AUTHOR]

A binomial low-pass filter provides the flattest passband response but, slow attenuation transition. This letter presents a design for improving the roll-off performance and reducing the size of the filter based on the negative-ℇ property of complementary split ring resonators (CSRRs), whilst maintaining the filter passband performance. The measured results indicate that the proposed structure achieves a flat pass-band with no ripples. Whilst also having a selectivity of 32 dB/GHz, which significantly exceeds the 17 dB/GHz selectivity of the conventional design. Furthermore, the proposed filter has reduced the filter size by 16%. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2406–2409, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22799 [ABSTRACT FROM AUTHOR]

Investigates a low radio frequency trenched coplanar waveguide (CPW) transmission-line structure with the use of evaporated aluminum tracks on a high-resistivity silicon. Reasons for the method use; What experimental results showed; How the proposed waveguide structure may be utilized in a specific fabricated process.