Orthogonal Phase Difference Research Articles

A 3D printed low‐profile wideband circularly polarised elliptical integrated lens antenna

AbstractThe authors presents a low‐profile wideband circularly polarised (CP) millimetre‐wave (mmWave) elliptical integrated lens antenna (ILA) fabricated by dielectric 3D printing technology. The proposed lens is integrated with a dielectric polariser and an air cavity for phase compensation, which can transfer incident waves from linearly polarised (LP) to planar CP waves over a wide bandwidth. Compared to the classic bifocal ILA, the proposed lens has a low profile. The phase compensation is performed by introducing a specifically shaped air cavity, which greatly reduces the length and weight of the lens. The polariser causes the two electric field components Ex and Ey to degenerate with an orthogonal phase difference, which results in the wideband characteristics of the antenna. The polariser, air cavity and lens can be conveniently and precisely fabricated by low‐cost 3D printing technology. Measurements show that the proposed ILA has a wide axial ratio (AR) bandwidth of 21.9–32.6 GHz, while the gain reaches 22.54 dBic with a 38% size reduction and a 60.7% weight reduction. Benefiting from the low profile, high gain, wide bandwidth and low cost, the proposed ILA has great potential to be the candidate antenna for 5G applications and satellite communications.

Compact and bandwidth-enhanced circular-polarized dipole antenna for 5G base-station applications

ABSTRACT A miniaturized and wideband circular-polarized (CP) dipole antenna with couple-feed has been developed for 5G base-station applications. In this design, two novel L-shaped short stubs working as the couple feed are introduced to excite the orthogonal dipole with the orthogonal phase difference. Therefore, CP radiation is realized on the orthogonally arranged dipoles. In addition, a stub-loaded square-ring dipole is utilized to generate another resonant frequency at low frequency, which broaden the working bandwidth and achieve the miniaturization design. To further expand the impedance and axial ratio bandwidths, four branch lines are adopted in the center of crossed square-loops dipoles. The proposed CP antenna using couple feed was finally fabricated and tested. The simulated and measured impedance bandwidth for |S11| < −10 dB is 65.0% from 1.55 to 3.05 GHz. The measured 3 dB axial ratio bandwidth is 37.5% (1.95–2.85 GHz). The measured results prove that this CP antenna can be applied to wideband base-station applications.

Nucleon Electromagnetic Form Factors at BESIII

The electromagnetic form factors (EMFFs) of the nucleon represent the simplest structure observables and serve as a testing ground for our understanding of the strong interaction. Using 669 pb−1 of data collected for a momentum transfer q2 (= −Q2) between 4.0 and 9.5 GeV2, the BESIII experiment obtained the most precise results on the nucleon magnetic form factor GM (the EMFF ratio Rem) up to date, with a relative precision of 1.8% (3.4%) for the proton and preliminary results with 8.9% (28%) for the neutron. An interesting oscillating behavior has been observed in the effective FF for both proton and neutron after the subtraction of the dipole-like parameterization, with an almost orthogonal phase difference between proton and neutron, indicating an unknown intrinsic dynamic hidden in the nucleon structure.

Asymmetric CPW Fed Miniaturized dual polarized monopole Antenna for WLAN/WiMAX Applications

An Asymmetric coplanar waveguide (CPW) Fed Miniaturized dual polarized (linear Polarized and Circularly Polarized) monopole Antenna Implemented. The Inverted-L Strip monopole antenna and the asymmetric ground plane for WLAN/Wi MAX applications are presented. Monopole antenna mainly icludes asymmetric ground plane which are fed with Coplanar Wave inverted L-shape strip and a slit embedded on the ground plane providing an orthogonal phase difference were designed to generate CP radiation. Inverted-L shape strip resonance and matching condition are examined by high-frequency structure simulator (HFSS) and the prototype is designed and measured. The measure simulated results shows that the monopole antenna impedance band-width with at −10 dB of 92.5 %( 3.36-6.66GHz) and a 3-dB axial-ratio bandwidth of 53.9 %( 5.4 -6.39 GHz) could be completed which could absolutely cover the WLAN (5.725 GHz - 5.85 GHz) band. Meanwhile, a linear polarization is also bought which could absolutely cover the WiMAX (3.3 GHz -3.7 GHz) bands. Orthogonal phase difference and average peak gain for lower band 1.9 dB and upper band 2.48 dB have been achieved, respectively.

35-GHz Wideband Circularly Polarized Patch Array on LTCC

A 35-GHz wideband circularly polarized (CP) patch array of $2\times 2$ elements using low-temperature cofired ceramic technology is presented. The widened 3-dB axial ratio (AR) bandwidth is achieved by constructing a $1 \times 2$ sequentially rotated CP patch array with small inner-element spacing in the antenna element. The antenna element consists of two close circular patches with diagonal perturbations, and the patches are rotated with respect to each other. The two patches are fed with equal amplitude and orthogonal phase difference using one probe, which has one vertical part and two different horizontal parts. The fabricated array with a dimension of $15.3 \times 28.3\times 1.3$ mm3 shows wide −10-dB $\mid S_{11} \mid $ and 3-dB AR bandwidths of over 29.6% and 26%, respectively. The measured maximum gain of the four-element array is 9.3 dBi with slight fluctuations over 31–39 GHz frequency range.

A Wideband Millimeter-Wave Circularly Polarized Antenna With 3-D Printed Polarizer

This paper presents a wideband circularly polarized millimeter-wave (mmw) antenna design. We introduce a novel 3-D-printed polarizer, which consists of several air and dielectric slabs to transform the polarization of the antenna radiation from linear to circular. The proposed polarizer is placed above a radiating aperture operating at the center frequency of 60 GHz. An electric field, ${E}$ , radiated from the aperture generates two components of electric fields, ${E} _{\mathrm {x}}$ and ${E} _{\mathrm {y}}$ . After passing through the polarizer, both ${E} _{\mathrm {x}}$ and ${E} _{\mathrm {y}}$ fields can be degenerated with an orthogonal phase difference which results in having a wide axial ratio bandwidth. The phase difference between ${E} _{\mathrm {x}}$ and ${E} _{\mathrm {y}}$ is determined by the incident angle $\phi $ , of the polarization of the electric field to the polarizer as well as the thickness, ${h}$ , of the dielectric slabs. With the help of the thickness of the polarizer, the directivity of the radiation pattern is increased so as to devote high-gain and wideband characteristics to the antenna. To verify our concept, an intensive parametric study and an experiment were carried out. Three antenna sources, including dipole, patch, and aperture antennas, were investigated with the proposed 3-D-printed polarizer. All measured results agree with the theoretical analysis. The proposed antenna with the polarizer achieves a wide impedance bandwidth of 50% from 45 to 75 GHz for the reflection coefficient less than or equal −10 dB, and yields an overlapped axial ratio bandwidth of 30% from 49 to 67 GHz for the axial ratio ≤ 3 dB. The maximum gain of the antenna reaches to 15 dBic. The proposed methodology of this design can apply to applications related to mmw wireless communication systems. The ultimate goal of this paper is to develop a wideband, high-gain, and low-cost antenna for the mmw frequency band.

A novel wideband and circularly polarized cross-dipole antenna

In this paper, we present a novel wideband circularly polarized (CP) composite, called cavity-backed crossed dipole antenna for 2.45 GHz industrial, scientific, and medical (ISM) band wireless communication. To excite the CP radiation effectively, a curved-delay line providing an orthogonal phase difference among the cross-dipole elements is attached at corners of the sequentially rotated elements. By choosing a proper radius of the curved-delay line, a wide input impedance of the antenna can be realized. Unlike conventional cross-dipole antennas, the proposed cross-dipole antenna is designed with an open stub added to the radiating arms of the dipole so that both impedance and axial ratio bandwidths are enhanced. The antenna is center-fed by a 50-Ω coaxial cable and is placed above a cavity-backed reflector to obtain a directional CP radiation pattern. With the advantage of being center-fed, a symmetric CP radiation pattern can be achieved across the entire operating bandwidth. To further improve the directivity and the radiation pattern, a rectangular cavity-backed reflector is used. Simulated and measured results confirm that the proposed antenna has good CP characteristics. The proposed antenna obtains a broad 3-dB axial ratio bandwidth of 49% (1.20 GHz, 1.96–3.16 GHz) and an impedance bandwidth of 67.7% (1.66 GHz, 1.69–3.35 GHz) for reflection coefficient (S11) ≦ −10 dB. It also yields an average CP gain of 9.2 dBic across the operating bandwidth and a peak CP gain of 10 dBic. Copyright © 2016 John Wiley & Sons, Ltd.

High-efficiency polarization conversion based on spatial dispersion modulation of spoof surface plasmon polaritons.

In this paper, we propose to achieve high-efficiency polarization conversion based on spatial dispersion modulation of spoof surface plasmon polaritons (SSPP). Different k is firstly designed in the two transverse directions by aligning an SSPP-supporting fishbone structure in y direction while maintaining free space in x direction. The orthogonal phase difference is introduced by larger k of SSPP waves for y-polarized component of incident waves. Meanwhile, to achieve high efficiency, gradient k in z-direction is designed so that the y-polarized component of incident waves can be coupled perfectly as SSPP waves. By rotating the fishbone structure with respect to the polarization direction of incident waves, different polarization states for transmitted waves can be realized. As an example, a polarization converter prototype with the central working frequency f = 8GHz was designed, fabricated, and measured. Both the simulation and experiment demonstrate the high-efficiency linear-to-circular (LTC) polarization conversion in 6.9-9.6GHz.

Six Degrees of Freedom Mobile Inductive Power Transfer by Crossed Dipole Tx and Rx Coils

Crossed dipole coils for the wide-range 3-D omnidirectional inductive power transfer (IPT) are proposed. Free positioning of a plane receiving (Rx) coil is obtained for an arbitrary direction within 1m from a plane transmission (Tx) coil. Both the Tx and Rx coils consists of crossed dipole coils with an orthogonal phase difference; hence, a rotating magnetic field is generated from the Tx, which enables the Rx to receive power vertically or horizontally. Thus, the 3-D omnidirectional IPT is first realized for both the plate type Tx and Rx coils, which is crucial for practical applications, where volumetric coil structure is highly prohibited. This optimized configuration of coils has been obtained through a general classification of power transfer and searching for mathematical constraints on multi-D omnidirectional IPT. Conventional loop coils are thoroughly analyzed, and verified to be inadequate for the plate-type omnidirectional IPT in this paper. Simulation-based design of the proposed crossed dipole coils for a uniform magnetic field distribution is provided, and the 3-D omnidirectional IPT is experimentally verified by prototype Rx coils for a wireless power' zone of 1 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> with a prototype Tx coil of 1 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at an operating frequency of 280 kHz, meeting the power matters alliance. The maximum overall efficiency was 33.6% when the input power was 100 W.

SU‐D‐18C‐03: In Vivo MR Imaging Using a Combined Single‐Point Dixon and Phase‐Sensitive Inversion Recovery Technique

Purpose:To demonstrate combined single‐point Dixon water/fat separation and phase sensitive inversion recovery imaging in in vivo brain images acquired in a single scan.Methods:A single inversion recovery image is acquired with an inversion‐time (TI) selected to maximize the dynamic range of the longitudinal magnetization of the water signals and at an echo time (TE) to introduce an orthogonal phase‐difference (i.e. 90°) between the fat and water signals. In the image reconstruction, spatially smooth background phase errors due to static magnetic field inhomogeneity are estimated by applying a region growing based phase correction algorithm: the algorithm first determines spatial phase jumps of 180° and then the second spatial phase jumps of 90°. After the background phase‐errors are removed from the acquired image, phase sensitive inversion recovery (PSIR) water‐only image and a separate fat‐only image can be generated as the real and imaginary parts of the phase‐corrected image, respectively.Results:The pulse sequence was implemented on a 3T whole‐body clinical scanner and a single brain image of a healthy volunteer was acquired. The acquired image was confirmed to contain an orthogonal phase difference between water and fat boundaries and 180o phase difference between the boundaries of long and short T1‐water tissues. The background phase errors were successfully determined and removed by the proposed phase correction algorithm and uniformly separated fat‐only and PSIR water‐only images were reconstructed without artefacts.Conclusion:We demonstrated combined single‐point Dixon water/fat separation and PSIR imaging in in vivo brain images acquired in a single scan. Such images can be useful when fat suppression and enhanced T1‐contrast are desired. Potential areas of application may include imaging of the brain or myocardium.

A Wideband Circularly Polarized Cross-Dipole Antenna

This letter introduces a wideband circularly polarized (CP) cross-dipole antenna fabricated on a double-layered printed circuit board (PCB) substrate for 2.45-GHz ISM band wireless communications. Unlike conventional cross-dipole antennas, the proposed cross dipole is designed with wide open ends such that both impedance and axial-ratio (AR) bandwidths are enhanced. In addition, to excite the CP radiation effectively, a curved-delay line providing an orthogonal phase difference among the cross-dipole elements is attached at the corners of the sequentially rotated elements. By choosing a proper radius of the curved-delay line, a wide input impedance of the antenna can be realized. The antenna is center-fed by a 50- Ω coaxial cable and is placed above a square reflector to obtain a directional CP radiation pattern. With the advantage of centered feed, symmetric CP radiation patterns can be achieved across the entire operating bandwidth. Simulated and measured results confirm the proposed antenna produced good CP characteristics. An impedance bandwidth (for VSWR ≤ 2) of about 50.2% (1.99-3.22 GHz) and the 3-dB AR bandwidth of about 27% (2.30-2.9 GHz) around the center frequency of 2.45 GHz were measured. The antenna has an average CP gain of 6.2 dBic across the operating bandwidth and the maximum gain of 6.8 dBic at the center frequency. The size of antenna is 0.45λ×0.45λ×0.24λ.

Geoelectric crustal structures off the SW border of the São Francisco craton, central Brazil, as inferred from a magnetotelluric survey

SUMMARY A magnetotelluric (MT) survey of the crust beneath sedimentary basins and thrust sheets along the southwestern edge of the Sao Francisco craton, central Brazil, reveals intricate electrical characteristics that are interpreted in the context of Proterozoic collision tectonics and horizontal transport of allochthonous rock units, emplacement of Cretaceous hypabyssals, lavas and diatremes of ultrapotassic–mafic composition, and occurrence of induced seismicity. The data exhibit strong distortions represented by 3-D induction effects and galvanic disturbances resulting from shallow structures, frequency and site dependence of electrical strike, and inhomogeneous anisotropic layers with smoothly varying phase split, conductance and azimuth of the highly conductive direction. Geoelectrical and orthogonal phase difference directions, 2-D inversion, and forward modelling characterize three distinct subhorizontal sections showing two anisotropic conductors within a highly resistive crust, laterally segmented into unique blocks. The model for the uppermost crust section has E–W geoelectric directions and a 15–30 S anisotropic zone at a depth of approximately 1–2 km along the entire profile. This conducting layer is interpreted to represent a brine-filled fracture layer possibly controlled by the present-day state of crustal stresses, as disclosed from reservoir-triggered quakes. The mid-crust section presents a deeper conducting zone located at depths below 10 km. It is defined by stronger MT responses having phase split directions oscillating from WNW–ESE to E–W beneath sites in the central-western area (Parana basin and allochthonous cover units) and NNE–SSW in the northeastern region (autochthonous platform units and Sanfranciscana basin). Anisotropy is greater than an order of magnitude in the highly conductive direction, with conductance in the range of 250–400 S. Conjecturally, the source of this anomalous feature would come from interconnected grain-boundary phases and hypersaline fluids, exsolved and precipitated from upwelling Cretaceous magma. In the central-western area, favourable trapping of conductors was constrained along a nearly E–W direction, feasibly associated with relic structures inherited from Brasiliano/Pan African continental collisions. Along the northeast, however, the coincidence with superficial NNE–SSW structural directions suggests a localized direct causal relationship with the trend of extension related to magma emplacement. The lower crust has a highly resistive quasi–1-D section along the entire profile that prevails also at uppermost mantle depths. Thus, whereas the brittle crust would have reconciled subhorizontal strain with fluid percolation related to uplift and magma emplacement, a mechanically coupled and stronger lower crust/upper mantle would have controlled the deep magma generation during Cretaceous distention pulses.