Haobin Zhang

Wideband high gain circularly polarized UHF RFID reader antenna

This paper presents a wideband and high gain circularly polarized ultra-high-frequency (UHF) radio frequency identification (RFID) reader antenna. Such antenna is composed of one main radiation patch and one parasitic radiation patch with air as the dielectric layer. And two feeding lines connect to the main radiation patch with 90 deg phase difference. Numerical optimizations and experimental demonstrations are performed to investigate the performances of the proposed antenna and good agreements are achieved. This antenna can cover the whole UHF RFID frequency band (840–960 MHz) with gain of 9.7 dBi, which is suitable for universal UHF RFID applications.

A 6–18 GHz log-periodic monopole end-fire antenna based on microstrip-to-slotline transition

This paper presents a novel wideband log-periodic monopole end-fire antenna fed by a microstrip-to-slotline transition feeding network. The proposed transition consists of a microstrip stub and slot stub to achieve the wideband impedance matching, and remove the inverting converter and correct the errors in conventional log-periodic antenna array. The proposed novel log-periodic monopole antenna covers 6 GHz–18GHz (S11< −10 dB) with flat gain of 7–8 dBi, and front-to-back ratio better than 18 dB.

On massive MIMO antenna topologies using total power in the azimuth and zenith domains

In this paper, we present an approximate expression for the spatial correlation of massive MIMO antenna topologies. The underlying concept of the proposed model is that the total power is relative to the true distribution of power in the azimuth and zenith domains. Simulation results using measured distribution of angles of departure (AOD) support the existing fact that massive MIMO convergence metrics do not demonstrate any sensitivity to antenna topology.

A 6–18GHz wideband SIW H-plane dual-ridged end-fire antenna

A 6–18 GHz wideband substrate integrated waveguide (SIW) H-Plane dual-ridged end-fire antenna is presented in this paper. A dual-ridged configuration is used to reduce the cut-off frequency and the characteristic impedance of the SIW. Three groups of air-vias applied in the front of the dielectric slab can improve the impedance matching. And two bending air slots are integrated in the top metallic layer of the SIW to correct the phase disorder and to further improve the impedance matching performance. With these novel improved designs, the proposed antenna shows experimentally a good impedance matching (|S11| < −7 dB)) and exactly end-fire gain (> 4.2 dBi) performances in the frequency range of 6–18 GHz. The proposed antenna also keeps low-profile and easy flush-mounted characteristic which is suitable for conformal applications.

A 6–18 GHz cavity-backed log-periodic-slot end-fire antenna for conformal application

A 6–18 GHz log-periodic slot-inspired cavity-backed end-fire antenna for conformal application is proposed in this paper. The log-periodic structure with 10 slot elements is applied to cover 6–18 GHz frequency band and the metallic cavity is placed under each slot element to keep wideband performance and prevent the effects of large metallic holder on the radiation pattern. A dielectric cover is used to improve the antenna performance and a broadband microstrip-CPW transition are inserted in the antenna as the feeding network. With these novel designs, the proposed antenna shows experimentally a good return loss and end-fire gain performances in the frequency range of 6–18 GHz. The proposed antenna also keeps low-profile and easy flush-mounted characteristics.

Wire-array-applied ultrafine tungsten wire coated with Al–Mg alloy layer via electron beam evaporation

Al–Mg alloy coatings were deposited onto superfine tungsten wire substrates via electron beam deposition at electronic beam currents ranging from 80 to 120 mA. The effects of electronic beam currents and baking process on the surface characteristics of the aluminium–magnesium alloy coatings were investigated using scanning electron microscopy. Energy-dispersive X-ray was also used to investigate the composition of the coatings according to the chemical components of the source materials. X-ray diffraction results suggested that the Al–Mg alloy coatings consisted of an Al12Mg17 intermetallic compound and pure aluminium phase. Electrochemical measurements determined the corrosion protection performance of the aluminium–magnesium alloy coatings with different magnesium contents. Specimen tensile properties were related to electron beams and surface roughness. The anti-corrosion performance of the coatings was increased with magnesium content.

Three-Dimensional Spatial Fading Correlation of Uniform Rectangular Array Using Total Power of Angular Distribution

In this letter, we derive a closed-form expression for the spatial fading correlation (SFC) of a uniform rectangular array useful for evaluating correlated-based stochastic models. The underlying concept of the proposed model is that the true distribution of power is relative to the total power of the incident wave and dependent on azimuthal and elevation spreads. Verification is accomplished with the help of computer simulation where excellent agreement is found between theoretical and simulation results. Results support the existing developments that the SFC decreases as the antenna separation or azimuthal spread increases. For performance evaluation, we model the multiple-input–multiple-output channel on the assumption that the coupling matrix of the coupled receiving array differs from the decoupled array. Results highlight the promising potentials of the proposed model with an effective decoupling process. However, we observed that lower estimations of azimuthal spread and elevation spread increase the rate of deterioration in the bit error rate and not antenna spacing.

Compact W-band multi-layer four-way SIW power combiner/divider

In this paper, a compact W-band multi-layer four-way substrate integrated waveguide (SIW) power combiner/divider is analyzed and demonstrated numerically/experimentally. The proposed power combiner/divider is realized by using a highperformance transition structure between multi-layer SIWs and rectangular waveguide. Both numerical and experimental results indicate that such power combiner/divider shows the high portisolation, low insertion loss, high efficiency, wide band, and small lateral size.

A compact dual-band circularly polarized squarering slot antenna with a wide angle circularly polarization performance

A compact dual-band circularly polarized (CP) square-ring slot antenna with wide angel CP performance is proposed. The antenna is a two-layer structure. A cross strip is placed in the centerline of the slot to achieve a compact size. Two different kinds of perturbations are applied to the slots on the diagonal line of the slots for splitting the fundamental mode into two degenerate resonant modes with equal amplitudes and 90° phase-difference for CP performance. Due to the special structure, a wide angle CP performance is observed.

A novel low profile rectangle waveguide planar magic-T of Ka-band

With the research and application of monopulse antenna, Sum and Difference become an essential element. As the basic component, the magic-T should be paid attention to. Due to the drawback of large profile in traditional magic-T, one planar magic-T structure working at the Ka-band have been designed and simulated in this letter. The E-arm fed through a longitudinal coupling gap in the proposed structure is coplanar with other arms for saving valuable space in a minimization device such as Sum and Difference network. In order to fine return loss properties, one copper cylinder is added act as inductance element to disturb the electromagnetic field for improving impedance matching. As a result, the bandwidth (VSWR<;1.45) with 4 GHz is obtained at the resonance frequency of about 35.5 GHz. The performance of low loss, equal power divide, Low VSWR and high isolation have all been achieved and it is of significance in design sum-and-difference network which can work in Monopulse antenna acting as feeding network.