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The design of a shared-aperture dual-band differentially fed array antenna with microstrip grid and patches is presented in this letter. The patches as high-frequency elements operating at 38 GHz are inserted into microstrip grid array antenna (MGAA) operating at the low-frequency band of 28 GHz. The impedance bandwidth of MGAA can be enhanced from 3% to 16% at 28 GHz due to the introduced resonance from its coupling with the patches. The measurement shows that the proposed antenna can achieve the impedance bandwidths of 15.65% and 16.7%, isolation of more than 20 dB, and peak gains of 14.7 and 14.5 dBi at dual bands of 28 and 38 GHz, respectively. Therefore, the design scheme will be useful for the dual-band millimeter-wave 5G applications.

A liquid crystal (LC)-based three-element microstrip parasitic array with beam switching is presented in this study. To understand the beam switching mechanism, a simple theoretical model of three-element Yagi antenna on the ground is given and analysed. In the proposed microstrip parasitic array, LC permittivities under three elements can be adjusted by bias voltages to control their resonant electrical lengths. In the tuning process, the LC-based antenna array can operate at three modes to obtain three beam switching directions. The measured results show that three beam tilt directions (θ = 59°, −2°, −57°) in the H-plane are achieved.

A dual-band differential shifted-feed microstrip grid array antenna (DSF-MGAA) with two parasitic patches is presented in this communication. By moving the feed location, a conventional MGAA (C-MGAA) can be turned into an SF-MGAA for dual-band operation. The high-frequency band of SF-MGAA corresponds to the operation mode of the C-MGAA, and its low-frequency band is similar to that of the patch or meshed patch antenna. A new differential feeding scheme and two parasitic patches are adopted to improve the impedance bandwidth of SF-MGAA. The proposed DSF-MGAA can cover a dual band of 3.7 and 28.5 GHz. The measured −10 dB impedance bandwidths of 3.4% and 4.5%, which correspond to the peak gains of 8.98 and 19.2 dBi, are obtained in the low- and high-frequency bands, respectively. The DSF-MGAA can be a potential candidate for the future dual-band wireless communication.

An electrically steerable parasitic array radiator in package based on liquid crystal (LC) is presented. It consists of one main and two parasitic inverted microstrip patch elements on an embedded LC layer with direct current bias. The antenna is designed to operate under the voltage mode at Ka-band. By varying the induced voltages on parasitic elements, the main beam can be steered to the desired direction. Measured results show that the pattern can be steered from –27° to +29° continuously in the H-plane at 28 GHz. The peak realized gain is 6.03 dBi with 1 dB variation within the steering range. The array achieves an 8.3% impedance bandwidth and avoids both large direct current power consumption and complicated bias scheme, making it a good antenna candidate for millimeter-wave 5G access point applications.

The four-port cavity model is presented to study a differential dual-polarised annular-ring patch antenna operating at higher order mode TM12. Acceptable agreements among calculated, simulated, and measured impedances and radiation patterns are obtained. Theoretical analysis shows that the differential port-to-port coupling impedance is zero, and its isolation is theoretically infinite. The differential input impedance is about four times of the single-ended input impedance at the resonant frequency of higher order mode TM12. The differential operation can suppress the adjacent modes TM02 and TM22 near the operating mode TM12 and lead to a more symmetrical E-plane radiation pattern and lower cross polarisation level.

In this paper, a high-gain and Fans-Shaped Beam (FSB) antenna is designed. It is used as the array element of a Multiple-input, multiple-output (MIMO) radar with 192 virtual channels. Measurement result shows that the antenna can improve its radar imaging performance due to its enhanced ability to overcome multipath effects caused by reflection of ground, which can be understood by the principle of MIMO radar.

A new high performance maritime rescue antenna is presented, including VHF, UHF and GPS bands in buoy miniaturization environment. By using innovative method of coaxial design, each of their desired radiation pattern and return loss are achieved. Specially, two VHF antennas, with 10dB impedance bandwidth of 4% (155-162MHz) and 8% (230-250MHz) respectively, port isolation of 15dBi are carefully designed. Meanwhile, the gain of VHF antennas is greater than 2dBi in elevation plane and the variation less than 1dBi in azimuthal plane. Circularly polarized UHF antenna achieves the wide beamwidth of 120 degrees at 406MHz, under the gain of 4.5dBi in elevation plane and axis ratio less than 3dBi with quadrifilar spiral inverted-F structure and shorted stub. GPS antenna is in the form of microstrip patch, which has good radiation characteristics. All antennas are finally verified by both simulations and measurements, showing their great potential applications in maritime rescue system.

A novel structure of bondwire and microstrip lines for Chip-to-Chip inter-connection up to 130GHz is firstly pre-sented in this paper. Its realization is based on PCB heterogeneous integration process. In order to reduce its high inserted loss which mainly caused of high inductance of the bondwire, the microstrip line of the structure is then optimized. Simulated results show that the minimum insertion loss of 1.0 dB for the structure can be achieved, with the bandwidth more than 35 GHz in bands of 100-135 GHz.

A miniaturized and high frequency response 35 GHz frequency modulated continuous wave (FMCW) radar system is presented for short range target detections. The system mainly consists of two antennas, a single chip transceiver and a signal processor. Thanks to our design and integrated techniques, high performance of the system is achieved and also verified by experimental results using our fabricated prototype. Our results show that the detection accuracy of 0.2m can be achieved for 15cm *15cm metal targets within detection distance of 12m, along with the radar system total size of 29mm in diameter, which agrees well with our design.

Two kinds of 60 GHz integrated planar patch array antennas with high gain and low profile are designed and implemented on Rogers3003 substrate. The antennas have the advantages of low profile, high isolation, and low insertion loss, both antennas have a gain of about 12 dBi, radiation efficiencies are 91% and 93%, bandwidths (|S11

A miniaturized, low-power and short-range 60 GHz frequency modulated continuous wave (FMCW) radar system is presented for small size target detection. It mainly consists of two antennas, a transceiver and a signal processor. The system design, subsystem integrated realization and performance verification is developed. Experimental results using our fabricated prototype show that the detection accuracy of 0.2m can be achieved for 15cm*15cm metal targets with detection distance of 15m under the system total size of 29mm in diameter and 5mm height conditions, which agrees well with our design.

A new high performance two-element V2X antenna array is presented, which is interspersed between two LTE antennas and designed in shark-fin environment. By using the specific designed lines and the closely EM coupling features, the desired current distributions in the element are achieved. Its high performance, with 10dB impedance bandwidth of 5% (5.7-6.0GHz), port isolation of 23 dB under the gain of 5.8dBi in elevation plane and the variation less than 5dBi in azimuthal plane, are finally verified by simulations and measurements, showing the great potential applications in automobile wireless communications.

A simple method for modeling the circular array and calculating its radiation pattern from a unit antenna’s spherical near-field data is presented. This method utilizes near-field data to calculate the transformation coefficient of spherical wave expansion (SWE) and thus performs a near-field to far-field transformation to obtain the radiation field. Then, the circular-ring antenna array’s radiation field is obtained by using a modified array factor. Comparison between full-wave simulations and presented method demonstrates the accuracy and efficiency of our method.

This study demonstrates comparisons of power to failure for SiGe-based low-noise amplifiers by injecting high-power microwave pulses. A general equation was derived to calculate power to failure, which depends on pulse width and its duty cycle. Two types of silicon–germanium (SiGe) transistors were modeled, and their temperature distributions were simulated. The pulse thermal resistance, thermal capacitance, and breakdown temperature were calculated and determined. Results show that the power to failure of the two transistors depend on the number of slots, pulse thermal resistance, thermal capacitance, and breakdown temperature, although these transistors exhibit nearly similar structures. In addition, calculated and measured results show close correlations. A summary for calculating the power to failure of a type of SiGe transistor is provided.

A differential probe-fed liquid crystal (LC)-based frequency tunable circular-ring patch antenna is presented. Besides, cavity model is extended to analyze the LC-based antenna for the differential operation. According to the cavity model, the permittivity and loss tangent of the LC are extracted from the measured differential reflection coefficients. Acceptable agreements among the measurement, simulation, and calculation for differential impedances, reflection coefficients, and radiation patterns are obtained and also validate the extraction method and model. More importantly, the extended cavity model can provide a deep physical insight into the LC-based antenna.

The frequency band ratio of dual-band microstrip grid array antennas (MGAA) is analyzed in this paper. Three dual-band MGAAs with different long side numbers are simulated to obtain the relationship between high and low operation frequency. Based on simulated results of the three antennas, high and low operation frequency ratio has a linear relationship with the low and high frequency resonant length ratio. By using the relationship, it is easy to estimate high and low band operation frequencies of dual-bandMGAAs.

A new design method for radio communication algorithm verification is presented in this paper. When developing communication algorithm on Field-Programmable Gate Array (FPGA) based Software Defined Radio (SDR) system, traditional steps include the algorithm simulation, FPGA synthesis and implementations, hardware validation and iterative adjustment. In general, the algorithm simulation step is entirely isolated with hardware environment. More pressures are added on hardware debug process and this will lead to a longer production period. New generation of FPGA products consists of both ARM hard cores and FPGA arrays. Due to its existence of ARM core, data acquiring system is easy to be built. When developing algorithm and optimizing parameters, data could be obtained directly from hardware and be simulated on computer in real time. The algorithm could be directly verified on hardware environment without building FPGA model. Therefore, algorithm developing process could be accelerated.

In this paper, a negative first order resonance (NFR) antenna is presented, based on a novel unequal mushroom structure. By using the dispersion relation and composite right/left-handed transmission-line (CRLH-TL) theory, the paper analyzes the miniaturization and wideband characteristics of the NFR antenna, and then verifies it through the simulation. The simulated results show that a radiation efficiency of 94%, and a peak gain of 1.85dBi at 1.4GHz at the radiation size of 0.1 $\lambda_{0}\times 0.1\lambda_{0}\times 0.004\lambda_{0}$ are obtained. In addition, an omnidirectional beam patterns are achieved.

A dual band notch UWB antenna based on Spiral corner feed Electromagnetic Band Gap (SCF-EBG) Structure is proposed. Two SCF-EBG structures are positioned alongside the feed line of the UWB antenna. The SCF-EBG structures produce two notch band at 3.5 GHz and 5.8 GHz which is in WiMAX band, the low frequency of fifth generation mobile communication (5G) frequency band in China and the wireless local area network interference band. The proposed antenna is suitable for UWB communication systems with dual band notch and a small size notch EBG structure.

A liquid crystal (LC)-based polarization reconfigurable cross-slot fed patch antenna is presented in this paper. The LC-based antenna is designed to operate at around 27.6 GHz. The antenna includes four perpendicular patches which are fed by a cross slot. By controlling LC permittivities under these patches, the different resonance frequencies can be obtained. Based on the degenerate mode theory, the frequency shift of the perpendicular patches generates the phase difference of 90°, and then the circular polarization will be achieved. When resonance frequencies of the patches are the same, linear polarization will be obtained. The simulated results shows that the LC-based antenna can have the left/right-hand circular polarization, and linear polarization switchable functionality.

The cavity model is extended to analyze a dualprobe-feed circular microstrip patch antenna for both differential and single-ended operations. Particular emphasis is given to the impedance characteristics in order to understand the relationship between the differential and single-ended input impedances. It is shown that the differential input resistance is four times of the single-ended input resistance at the resonant frequency of the fundamental mode.

A new compact dual-polarized integrated antenna base station (BS) array is proposed in this paper. It consists of one center linear arrays and two side one with their total size of only $356 \times 1000 \times 81\ \mathrm {mm}^{3}$. The center array is operated in full-band (0.69-0.96/1.7-2.7GHz) while the two sides arrays worked in high band (1.7-2.7GHz). The full-band elements are designed based on both our new high band feeding and low band (0.69-0.96GHz) Electromagnetic (EM) dipole techniques. The main performance features of the BS array, i.e., cross polarization discrimination (XPD) and 15 (11) dBi gains in their high (low) frequency band respectively, are fully designed and obtained by using simulations. The validities of the design are verified by the measurements, showing that the BS array have good potential applications in wireless BS.

This paper proposes a graphene loaded microstrip patch antenna with tunable frequency at THz. The antenna consists of a rectangular patch with a graphene pad connected to the radiating edge of antenna, and a broadband DC bias circuit to apply bias voltage to graphene pad. Meanwhile, the DC bias circuit can achieve open circuit to high frequency signal, which reduces the influence of DC bias circuit on the input impedance of the antenna. The surface impedance of graphene can be dynamically controlled by changing the applied bias voltage, thus the input impedance of the antenna can be adjusted. Then the tunable frequency of the antenna is realized. A prototype antenna operating at the frequency of 300GHz. The proposed design can achieve linear frequency tunability in the range below the initial operating frequency.

This paper presents a tunable frequency microstrip patch antenna using graphene. The antenna consists of a rectangular patch with a graphene pad connected to the radiating edge, and a metallic via used to connect graphene pad and ground. The imaginary part of the surface impedance of graphene is larger than that of the real part in THz band. So graphene can be regarded as a reactance component loaded into patch antenna. The surface impedance of graphene can be controlled by changing the applied bias voltage, thereby controlling the input impedance of the antenna. Then the tunable frequency of the antenna is realized. A prototype antenna operating at the frequency of 300GHz. The proposed design can achieve linear frequency tunability in the range above the initial operating frequency.

A microstrip grid array antenna is presented for dual band applications at 2.27 GHz and 17.7 GHz. By designing the location of the feed point, the antenna can operate at the two modes. One mode is corresponding to the normal operating scheme of the grid array antenna in the high frequency band. The other mode is similar with the operating scheme of the patch antenna in the low frequency band. The simulated results of the antenna are given and discussed.

A novel graphene ultra-wideband (UWB) planar rectangular monopole antenna with band-notched characteristics is proposed in this paper. The proposed antenna consists of the Fused Silica substrate, a gold coplanar waveguide (CPW) transmission line and a rectangular graphene radiating patch which has two cutting bevels in order to have larger bandwidth according to the former studies. By etching a slot on the signal line of CPW, band-notched property in the 0.122 THz is achieved. Simulated results of the antenna are presented and discussed.

This paper presents a novel brain imaging method, which is based on the transcranial vortex microwave beam (TVMB) illumination and the dynamic confocal collection (DCC). The TVMB is realized by a vortex antenna on the top of head, with its axis towards the center of the head while the DCC is a horizontal ring array of 8 antenna elements with the same center. It is found by simulation that the imaging performance can be improved greatly when focusing factor is introduced in the head model. The result shows that this approach is a very promising solution to achieve high quality microwave imaging for intracranial hemorrhage detection.

An improved hybrid implicit-explicit finite-difference time-domain (HIE-FDTD) method is proposed for simulating graphene-based patch couplers at terahertz (THz) for different physical and geometrical parameters, where the Drude model of monolayer graphene and the associated auxiliary differential equation (ADE) technique are implemented. In order to accurately model the curved graphene boundaries, the conformal FDTD method is further hybridized with the HIE-FDTD method, which results in a conformal HIE-FDTD method. Numerical results are presented for S-parameters and field distributions of the coupler, which can be adjusted effectively by changing the chemical potential and layer number of graphene patch or substrate permittivity.

The convolutional perfectly matched layer (CPML) is modified and implemented for one-step leapfrog hybrid implicit-explicit finite-difference time-domain (HIE-FDTD) method. Its stability is verified in a semi-analytical way and its effectiveness is demonstrated numerically. It is shown that even when time step size is large, the absorbing performance of CPML is still very good.

A new compact dual polarized co-axial antenna with gain greater than 8.0dBi is presented operated in 0.69GHz–0.96GHz/1.71GHz–2.69GHz. The size of the antenna is 286 × 286 × 81mm3. Its reflection coefficient and the cross-polarization isolation are less than −10.5dB (−12dB) and higher than 15dB (20dB) in low (high) frequency respectively. Measured results are agree well with the simulated one, verifying the availability of this antenna design.

A new Hilbert structure based EM meta-surface operated in 800–1000 MHz, is firstly presented in this paper for improving the isolation and radiation performance of a two-element antenna array. To verify the validity of our design, both the simulation and measurement are then carried out. Finally, their well-agreed results show that the isolation is increased by 5dB without degrading their radiating performance, making the design a good candidate for car wireless system applications.

This paper firstly explores the strong scattering effect of intracranial hemorrhage on transcranial vortex microwave beams. Full-wave simulation indicates that this effect has a potential to achieve high quality microwave imaging for intracranial hemorrhage detection.

Intracranial abnormal tissue microwave imaging (IATMI) is an effective method for timely diagnosis of intracranial hemorrhage (ICH). For better imaging quality, we study the intracranial focusing and strong scattering effects of transcranial vortex microwave beam (TVMB). We find by full-wave simulation in this paper that the topological charge (TC) of the vortex beam can effectively control the electromagnetic energy localized distribution of TVMB within human head.

A novel fifth-order elliptic cross-coupled wideband bandstop filter (BSF) is proposed and designed in this letter. It is devised by introducing additional electric coupling into two nonadjacent quarter-wavelength shunt stubs of a conventional commensurate line BSF. The selectivity and stopband rejection can be effectively enhanced by two extra transmission zeros generated from the coupling. The proposed BSF is designed directly from the normalized lowpass prototype by using the design formulas, which are derived based on the rigorous correspondence between the BSF and its lumped prototype in the $S$ -plane. In order to demonstrate our design, a BSF example is developed, with a measured 27.2 dB stopband over a fractional bandwidth of 141.7%.

A cross-coupled wideband bandstop filter (BSF) with a 5th-order quasi-elliptic response is proposed and investigated in this letter. The BSF is composed of stepped-impedance coupled line connected by an open-circuited shunt stub. An enhanced selectivity and stopband rejection can be achieved as a result of two new transmission zeros, generated from the stepped-impedance coupled line. Based on the derived rigorous correspondence between the BSF and its lumped prototype, design of the proposed BSF can be handled as the same to the lumped network. A BSF example is given with measured stopband attenuation of 34.4 dB over a fractional bandwidth of 113.4%.

A novel compact dual-band antenna array with high isolations is presented in this paper. It consists of four antenna elements with two feeding networks, and it operates at dual-band of 0.89–0.96 and 1.7–2.2 GHz with return loss more than 9 dB, respectively. Two feeding networks are made of a wideband balun and a Wilkinson power divider, respectively. The two-port symmetrical array is constructed using the neutralization technique (NT), leading to the array port isolation over 30 dB from 0.5 to 3.0 GHz. Such a compact dual-band antenna array is realized and its gains and normalized patterns for both ports ${\rm P}_{1}$ and ${\rm P}_{2}$ are measured, with good agreements obtained in comparison with the simulated ones.

This paper proposes a new type of compact tunable bandpass filter with bandwidth tuning and out-of-band fixed rejection. Because we employ the modified Hilbert fractal structure loaded with varactors as resonators, the tunable filter has a very compact configuration and a constant shape over the entire tuning range. The frequency selectivity is improved by introducing a cross coupling between the source and the load. As a result of the utilization of a pair of properly designed feedlines, the frequency tuning and the out-of-band rejection of the filter are independent of each other, which simplifies its operation significantly. Two filter prototypes have been realized with the same size of 25.0 × 17.0 × 1.0 mm3. Their superior performances have been demonstrated experimentally, with good agreement obtained between their simulated and measured S-parameters.

In this paper, the hybrid implicit-explicit finite-difference time-domain (HIE-FDTD) method is proposed for efficient simulation of graphene-based frequency selective surfaces (GFSS) at Terahertz band, with the Drude model of monolayer graphene and associated auxiliary differential equation (ADE) technique implemented into the numerical methods for solving the Maxwell's equations. Numerical simulations show that the transmission coefficient of the GFSS can be tuned effectively by varying the chemical potential or layer number of graphene patch.

A beam-steering array operating in the 28-GHz band is described, including a 1-by-4 patch antenna array, liquid crystal (LC) based microstrip meander line phase shifters and feeding networks. The RF signal is coupled to the patch antenna array from the slots in the ground plane. The LC phase shifters are implemented in a kind of inverted microstrip line (IMSL) topology by filling liquid crystal between two RT/duroid 5880 substrates(e r = 2.2, tanδ = 0.0009) with a figure-of-merit of 45.2°/dB at 28 GHz. Simulation results of the scattering parameters and the radiation patterns of the antenna are presented and discussed here.

In this paper, a new low profile and closely spaced dual-polarized antenna (DPA) is proposed. The low profile DPA element with height of 0.112λ is made of a four-port radiator and two feeding networks. Simulated results show that the element can cover the frequency band of 2.535–2.655GHz, along with reflection

A 60GHz Massive-MIMO patch antenna array, consisting of 8×16 elements, is presented in this paper. To overcome its heat problem caused by active circuits in its system, heatsink (HT) solution around the array are explored, focusing on the impact of the HT on array radiating characteristics. Simulation shows that our proposed array and HT solution is a very promising for 60 GHz Massive-MIMO system applications.

A study of UWB on-body communication system performance, with the WiMax ofi-body electromagnetic interference (EMI) existence, is presented. Firstly, a compact UWB antenna with good on-body performance is verifled and chosen as our reference antenna. Using this realistic antenna, channel transfer function (CTF) of UWB on-body channel in an indoor room is investigated by measurements. Based on the measured data, the parameters of its pathloss model and its power delay proflle (PDP) model are extracted respectively. Secondly, a new body channel communication system model, composed of the on-body and ofi-body dual-link channel, together with UWB and WiMax signal models are presented. Finally, UWB on-body communication performances under difierent WiMax ofi-body EMI levels are studied by simulation. Simulated results show that this on-body system performance is quite limited and easily afiected by the ofi-body WiMax EMI. It is pointed out that the existing UWB on-body communication abilities should be greatly improved when WiMax ofi-body EMI signals are considered.

A broadband dual-polarized four-port (DPFP) antenna is presented in this paper, which consists of a radiation element and a feed network. It is very compact in size, with the diameter of 150.0mm and the height of 47.0mm, with the following unique properties: (1) it has hybrid beam-forming capability and operates at two modes, which depends on its excitation; (2) its operating frequency range is from 0.96 to1.78GHz, and the return loss is about 10dB; (3) its insertion loss is (3 § 0:5)dB, with its balanced power splitting over the relative bandwidths of 37% at Mode 1 (180 - § 5 - phase shifting) and 55% at Mode 2 (§5 - phase shifting), respectively; (4) an isolation of 30dB at Mode 1 is obtained between the dual polarized ports, with the gain of 7.6dBi and 42 - of the 3dB-bandwidth at 1.25GHz; and (5) the gain difierence between Modes 1 and 2 is about 7dB, within the angle of i15 - • µ • 15 - for the same polarization at 1.25GHz. For the application of DPFP, a hybrid beam forming algorithm is proposed with an angular precision of 7 - and is validated by measurement.