Differential Feed Research Articles

Triple-Band Dual-Polarized SIW Cavity-Backed Differential Slot Antenna

A differential triple-band dual-polarized cavity backed substrate integrated waveguide (SIW) slot antenna is presented in this letter. The hybrid TE130, TE320, and TE140 modes of the square SIW cavity are excited by differential feed for a triple-band realization. The proposed antenna exhibits dual-polarized radiations at 9.06 GHz, 11.86 GHz and 14.23 GHz. An isolation better than 40 dB in all the three frequency bands between the differential ports is obtained. The proposed structure exhibits the differential gain of 5.4 dBi, 10.7 dBi and 9.5 dBi at 9.06 GHz, 11.86 GHz and 14.23 GHz, respectively. To validate the design approach, the proposed antenna is fabricated and its characteristics are measured.

28 GHz and 38 GHz Dual-Band Vertically Stacked Dipole Antennas on Flexible Liquid Crystal Polymer Substrates for Millimeter-Wave 5G Cellular Handsets

Minimizing the size of mobile antennas is necessary for integrating the components inside a mobile device. Wideband and multiband antennas are also required to cover various 5G mobile communication frequency spectra. This article presents a vertically stacked dipole antenna array operating in the 28/38 GHz dual-band. The proposed antenna is small and satisfies the need for wide bandwidth in the form of a dual band. The antenna structure has symmetric 38 GHz band radiators positioned above and below a multilayer substrate, and a 28 GHz band radiator positioned on the middle plane, providing a dual-band antenna structure with small lateral width. Herein, two types of antenna structures are proposed, each with a single-ended and differential feed structure for compatibility with various RF front ends. The single antenna yields −10 dB bandwidth for return loss of 23.9% and 14.4%, and gain of 4.8 and 4.6 dBi at 28 and 38.5 GHz, respectively. The 4-element antenna array yields a gain of 9.0 dBi at 28 GHz and 10.3 dBi at 38.5 GHz. It was fabricated on a flexible substrate and can be bent and inserted into the lateral edge of the terminal. The proposed antenna elements and arrays satisfy the performance factors requisite for millimeter wave 5G communication including compact size, wideband, dual-band, and adequate gain.

Research on boundary slip of hydrostatic lead screw under different driving modes

The flow state of oil film in the hydrostatic lead screw directly affects the transmission performance of the screw pair. The static and dynamic characteristics of a new type of double driven hydrostatic screw-nut pair (DDHSNP) are studied under different motion modes. The boundary condition of navier slip model is introduced into the lubricating mathematical model of DDHSNP, and the influences of boundary slip on the axial bearing capacity, axial stiffness and damping coefficient in micro scale are researched by finite difference method. The results show that when the motor runs at high speed (the rotating speed range of the screw and nut driven motor is 1000–9000 rpm), the existence of boundary slip leads to a improvement of the axial bearing capacity and stiffness coefficient of DDHSNP in the case of single-drive operation and dual-drive differential feed (the range of rotation difference is 10–100 rpm), which is more obvious under the single-drive mode. The increase rate of stiffness coefficient induced by boundary slip is much larger than that of bearing capacity. In addition, the boundary slip has little effect on the damping coefficient of DDHSNP in either single drive operation or dual drive differential operation.

High-Isolation Dual-Polarized Leaky-Wave Antenna With Fixed Beam for Full-Duplex Millimeter-Wave Applications

In this article, a high-isolation dual-polarized leaky-wave antenna (LWA) with a fixed beam is proposed for full-duplex millimeter-wave (mm-wave) applications. The proposed antenna consists of a dual-polarized LWA array and an orthogonally differential feeding network. The proposed dual-polarized LWA array is developed based on the proposed LWA unit cell, which is suitable for differential feed, and the open stopband is eliminated. The proposed feeding network provides two pairs of orthogonally differential excitation for the LWA array to realize the fixed beam with orthogonal polarization in boresight direction; the high interport isolation is implemented as well. The prototype for demonstration purposes is fabricated and measured. The measured results show that the proposed antenna exhibits an operating band from 27.6 to 29.5 GHz with a maximum gain of up to 24 dBi. Furthermore, the measured interport isolation is higher than 51 dB within the operating band, where the maximum isolation is up to 60 dB. The measured cross-polarization levels are also very low, less than −27 dB. The proposed antenna features high gain, high interport isolation, and good co-/cross-polarization isolation, achieving a good Tx/Rx separation for the in-band full-duplex applications at mm-wave frequencies.

Compact Differential Diplex Filtenna With Common-Mode Suppression for Highly Integrated Radio Frequency Front-Ends

A compact, differential diplex filtenna (DDF) with common-mode (CM) suppression is presented. A rectangular dual-mode patch is developed that operates in both its TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode and a reshaped TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">30</sub> mode to realize two passbands. Two capacitively loaded loop (CLL) resonators that work at different frequencies are combined with the dual-mode patch to enhance its operational bandwidth and to provide a second-order Chebyshev filter response for both passbands. A slot-coupled differential feed is adopted to suppress the harmonic and CM noise and to obtain symmetrical radiation patterns with low cross-polarization levels. The design process, which is based on filter synthesis theory, is detailed. A prototype operating over the 2.4G and 5.8G WLAN bands was fabricated, assembled, and tested. The measured results, in good agreement with their simulated values, confirm that it attains maximum broadside realized gains of 5.45 and 8.5 dBi and −10 dB fractional impedance bandwidths of 2.4% (2.42–2.48 GHz) and 5.2% (5.65–5.95 GHz) for the lower and upper passbands, respectively. Moreover, it exhibits good out-of-band rejection levels of 18 and 29 dB for the lower and upper stopbands, respectively.

Dynamic model of self-adaptive differential rotary feed system of a drill

It is impossible to advance mineral mining without using high-capacity and power-efficient machines in various operations, in particular, drilling. Design of any machine should specify engineering data of all components of the machine. This is infeasible without a comprehensive dynamic model of a machine, including inertia properties of parts and components, mechanical characteristics of drives, as well as properties and features of useful resistance forces to be overcome by the machine. This article discusses the layout of the differential rotary feed system of a drill, with detailed description of all components and operation mode. The main effect of this layout is self-adjustment of the velocity and feed of the rock-breaking tool as function of its motion resistance. The developed dynamic model of the rotary feed system is represented by a system of two differential equations. The generalized coordinates are assumed to be the angular motions of shafts of the baseline engine and the thruster. The differential equations allow synthesizing mechanism of the rotary feed system. The presented information can be useful for engineers and designers of self-adaptive rotary feed systems of drills.

Research on low-speed characteristics of differential double-drive feed system

Abstract. It is difficult to achieve high-precision control due to frictional nonlinearity by traditional linear control methodology for the classical drive feed system at low speed. Here, the double-drive differential feed system is proposed to reduce the influence of the nonlinear friction at the ball screw pair of a linear feed system operating at low speed. The dynamic models and the LuGre friction models of the classical drive feed system and the double-drive differential feed system are established, respectively. Based on these, the simulation models of the classical drive feed system and the double-drive differential feed system are established in MATLAB to study the critical creeping velocity of the table. Compared with the classical drive feed system, a lower stable velocity can be obtained for the table with the double-drive differential feed system, because the speed of both motors in the double-drive differential feed system is higher than the critical creeping speed of the classical drive feed system screw motor, thereby overcoming the influence of the Stribeck effect and avoiding the frictional nonlinearity at low speed.

Design of a New UWB Differential Tightly Coupled Dipole Array (D- TCDA)

Multifunctional arrays (MFAs) are widely used in RF electronic warfare, communications, radar, and sensing applications. Improvements in cooling technologies, high density packaging and ultra-wideband (UWB) transceivers are creating a paradigm shift in RF systems toward these MFAs. Another key enabler of these technologies is the use of UWB array apertures, which were impossible to design decades ago. In this paper, we present a new addition to the tightly coupled dipole array (TCDA) family that utilizes a patented UWB differential feed.

Optimized configuration of the joint stiffness for a dual differential feed system

Optimized configuration of the joint stiffness for a dual differential feed system

Broadband 120 GHz L-Probe Differential Feed Dual-Polarized Patch Antenna With Soft Surface

This article presents a broadband 120 GHz L-probe differential feed dual-polarized patch antenna with a soft surface. The impedance bandwidth is widened with additional resonance points by applying an L-probe feeding topology. Using differential feeding and soft surface, the overall radiation performance including the radiation pattern, cross-polarization, and isolation is improved for a wide bandwidth covering the targeted band, and the analysis of each structure is described in this article. The measured S11 bandwidth, peak gain, 3 dB gain bandwidth, and isolation are 28.3%, 9.8 dBi, 26.4%, and 28.5 dB, respectively. The proposed dual-polarized antenna reveals the widest S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> bandwidth, with a 3 dB gain when compared with the previously reported millimeter and sub-THz dual-polarized antennas. Moreover, to the best of the authors’ knowledge, the proposed dual-polarized antenna is demonstrated at the highest frequency compared with the previously reported dual-polarized antennas.

Fast water transport through biomimetic reverse osmosis membranes embedded with peptide-attached (pR)-pillar[5]arenes water channels

This study examined the feasibility and performance of a nanochannel-based biomimetic membrane (NBM) for brackish reverse osmosis (RO) desalination. Two types of peptide-attached synthetic nanochannels, (pR)-pillar[5]arenes (pRPH) and (pS)-pillar[5]arenes (pSPH), were incorporated into liposomes. pSPH is a diastereomer of pRPH and was used as a negative control (i.e. mutant) to pRPH in this work. The nanochannel-containing liposomes (e.g. pRPH-liposomes) were then immobilized into the active layer of the RO membranes via in situ interfacial polymerization on the top of a polysulfone support membrane to form NBM-pRPH membranes. To maximize the potential and benefits of the NBM-pRPH membrane, the physical characteristics of the polyamide layer was further tuned using some additives and the eventual membrane was named as NBM-pRPH-A. The NBM-pRPH-A membrane exhibited a water permeability of 6.09 L m−2 h−1 bar−1 and 98.2% NaCl rejection under a 15.5 bar applied pressure using 2000 mg L−1 as feed solution. The 62% flux increment with respect to the pristine control is postulated to arise from a thinner, less cross-linked (more free volume) and more hydrophilic active layer as well as the possible supplementary transport pathways of the pRPH-liposomes. The performance of the NBMs under differential feed pressures and temperatures further exemplifies the water permeation property of the pRPH nanochannels. Accordingly, the NBM-pRPH-A gave a water permeability higher than commercial RO membranes tested in this work (DuPont BW30 and Hydranautics ESPA2) as well as other RO membranes reported in the literature. This study provides a tangible foundation for the development of NBMs for brackish RO desalination.

Compact triple‐mode HMSIW balanced passband filter with intrinsic common‐mode suppression

AbstractIn this article, a compact triple‐mode balanced passband filter with intrinsic common‐mode (CM) suppression is designed by using a single isosceles right triangle perturbed half‐mode substrate integrated waveguide (HMSIW) cavity. The perturbation metallic vias are introduced to tune the first three resonant modes of HMSIW cavity to form a passband. Furthermore, the planar differential microstrip‐pin feed structure is designed to excite the perturbed substrate integrated waveguide cavity. Under CM operation, when the substrate's height is less than λg/4, the space between perfect electric conductor and perfect magnetic conductor cannot transmit electromagnetic wave, so CM noise can effectively cut off at the planar differential feed structure in a wide frequency range. Finally, a prototyped prototype at 4.5 GHz is designed and fabricated, and measured results show good agreement with simulated ones.

An ultra‐wideband out‐of‐phase power divider based on odd‐mode spoof surface plasmon polariton

In this article, a feasible design of an ultra-wideband power divider (PD) based on spoof surface plasmon polariton (SSPP) is proposed. A quasi T-junction transmission structure is composed of the sub-wavelength corrugated grooves drilled on the up metal layer, realizing the wideband and low loss for the propagation of the odd-mode SSPP wave. The consistency of the dispersion curves between the H-shaped and the U-shaped unit cells under the same dimension parameters ensures the smooth transition at the bifurcation point and out-of-phase property further. The odd-mode SSPP is effectively excited by using the microstrip-to-slotline convertor. Some design details like gradient corrugations and stepped slotlines are employed to achieve high-coupling efficiency from the input electromagnetic energy. The simulated and measured results show that the proposed PD achieves 180° ± 5° phase difference over an ultra-wideband from 3.3 to 9.8 GHz (a relative bandwidth of 99.24%) with high-transmission efficiency. The ultra-wideband out-of-phase property of this design has potential applications in the differential feed network.

Optimized Differential TCDA (D-TCDA) With Novel Differential Feed Structure

Modern phased arrays require large instantaneous bandwidths, wide fields of view, and low profiles to conduct multiple functions. Many of these phased arrays rely on emerging high speed ADCs and advanced balanced transceivers. The benefits of balanced front-ends include improved linearity, dynamic range, isolation, and noise resilience. The application of a differential phased array in such a system removes extraneous losses caused by baluns, though the issue of feed-borne E-plane scan resonances must be considered. We address the E-plane scan resonance issue through an improved Balanced Wideband Impedance Transformer (BWIT) feed for the ultra-wideband (UWB) Tightly Coupled Dipole Array (TCDA). This BWIT feed has already demonstrated mitigated common-modes over a 3:1 bandwidth ratio while scanning to low angles. Here, our differential TCDA (D-TCDA) is developed for the L-C band ( viz. 1.0 GHz to 6.1 GHz) with emphasis on resonance-free wide-angle scanning. Rigorous EM model and circuit analysis is included to verify the BWIT performance. Under a VSWR $8\times 8$ single-polarized prototype.

Wideband Dipole Array With Balanced Wideband Impedance Transformer (BWIT)

Within the context of modern digital phased array (DPA) radios, differential Radio Frequency (RF) front-ends provide much greater immunity to noise and distortion by suppressing second order harmonics. Recent advancements in differential RF front-ends offer high dynamic range, high linearity, and low noise in the transceiver chain. However, a major roadblock to fully differential systems is the presence of common-mode resonances. In this article, we present a novel wideband differential feed for dipole arrays that overcomes this bottleneck. Our dipole array is developed for the L-S band (viz. 1.05 GHz to 3.2 GHz) with emphasis on dual-linear polarization and resonance-free scanning to low angles. The novelty of this article is the Balanced Wideband Impedance Transformer (BWIT) feed that mitigates common-mode currents across the entire band while scanning to low angles. Array simulations are verified with measurements of an $8\times 8$ prototype in a volume of 384mmx384mmx57 mm. The array achieves resonance-free scanning across a 3:1 impedance bandwidth with VSWR <; 3 for the cases of $\theta = 0^{\circ }$ (Broadside), 45° (D-plane), 60° (E-plane) and across a 2.37:1 impedance bandwidth with VSWR <; 3 for the case of 45° (H-plane). Measured gain achieves near-theoretical values across the operating band.

Design of a Metasurface Antenna With Pattern Diversity

A dual-port metasurface (MS) antenna for pattern-diversity applications is proposed. The planar MS, consisting of 4 × 4 square patches, is excited by a driven patch. A pair of differential probe feed is used to drive the patch with broadside mode, while a stepped probe feed is employed in the center of the patch to generate conical mode. The capacitive-loaded stepped probe of the center feed is able to adjust the operating frequency of the conical mode and provide the two different modes with a wide overlapped frequency range. A prototype of the antenna was fabricated and measured for demonstration. The measured overlapped bandwidth (| S 11| < −10 dB) is 11.2% ranging from 5.11 to 5.72 GHz. Within the band, the measured peak gain is 11.5 dBi for the broadside mode and 6.8 dBi for the conical mode. High isolation of greater than 32 dB between the two ports is achieved over the band. Benefiting from the gain and bandwidth improvement brought by the MS, the proposed pattern diversity antenna is attractive for many wireless communication systems.

Wideband Differentially Fed Dual-Polarized Antenna for Existing and Sub-6 GHz 5G Communications

This letter proposes a differentially fed $\pm$ $45^{\circ }$ dual-polarized antenna with ultrawideband operation. It consists of two orthogonal stepped-dipoles backed by an inverted pyramidal cavity reflector for improvement in broadside gain. The stepped dipoles built on both sides of the substrate are constructed from small square pads and square loops for multiresonances to enhance the bandwidth. The dipoles are fed from four coaxial lines with a crossed-strip structure to accommodate the differential feed. The final design with overall size of 0.75 $\lambda _{\text{min}}$ × 0.75 $\lambda _{\text{min}}$ × 0.21 $\lambda _{\text{min}}$ ( $\lambda _{\text{min}}$ is the free-space wavelength referring to the lowest operational frequency) has been fabricated and measured. The antenna achieves a measured bandwidth of 74.2% (1.74–3.79 GHz) for return loss $>$ 15 dB and a measured isolation better than 43 dB among the differential ports. Its bandwidth can cover the frequency spectrums of the existing and new wireless communication systems such as 2G/3G/4G (1710–2690 MHz) and sub-6 GHz 5G (3100–3800 MHz). Additionally, the measured peak broadside gain is 10.5 dBi with cross-polarization level of $ 20 dB within the operational bandwidth.

Low-Cost CMOS Active Array Solution for Highly Dense X-Band Weather Radar Network

This article presents the development of a CMOS active array antenna unit cell as a potential solution for a highly dense, low-altitude short-coverage phased array $X$ -band radar network system. The antenna uses a cross-patch differential feed structure designed in a stacked configuration for bandwidth and cross-polarization enhancement. To overcome the limitations of current CMOS RF performance, a mirroring technique was applied at the element and subarray level. A 16-element array ($4\times 4$ elements), integrated with CMOS T/R modules in a tileable architecture, was developed and characterized. Measured results demonstrate that this proposed array offers cross-polarization levels less than -32 dB across the scanning range of ±45° in the principal planes for dual-polarized alternate transmit and alternate receive (ATAR) phased array weather radar.

Efficient Procedure to Design Large Finite Array and Its Feeding Network With Examples of ME-Dipole Array and Microstrip Ridge Gap Waveguide Feed

An efficient procedure to design a large planar array and its corporate feeding network is presented. The procedure is verified by $8 \times8$ and $16\times16$ arrays of magnetoelectric dipoles (ME dipole) fed by microstrip ridge gap waveguide (MRGW) through a narrow slot. This procedure is based on using the frequency-dependent effective input impedance at the port of each element, which includes the effect of the mutual coupling between the antenna elements, which is used to design the corporate feeding network. In addition, the far-field characteristics of the array parameters such as directivity, gain, and the radiation patterns are predicted using the pattern multiplication method including the mutual coupling. The results are verified with the full-wave numerical solution. The procedure requires limited resources and speed up the design cycle. In the presented examples, the array elements are directly excited by the MRGW, which provides more flexibility to design complicated feeding networks and allow for distances between the elements less than a wavelength. Therefore, grating lobes are avoided. To accommodate such constraints, special designs of the power dividers are performed to provide the symmetric location of MRGW lines to avoid coupling between the feeding network lines. Furthermore, a transition from waveguide WR-15 to the MRGW is proposed to differential feed of the array antenna. The $16 \times 16$ array of ME dipoles has been fabricated. The measurement results show a 19% matching bandwidth ( $\vert \text{S}11\vert dB) and measured gain above 30 dBi with radiation efficiency better than 71%, all within a common bandwidth of 56–66 GHz.

Design and implementation of speed fluctuation reduction for a ball screw feed system at low-speed operation

Abstract. In the high-precision servo feed system, when the permanent magnet synchronous motor (PMSM) is operated at low speed in the classical drive feed system (CDFS), the speed fluctuation caused by the motor torque harmonics seriously affects the speed smoothness of the servo system. In this paper, a novel double-drive differential feed system (DDFS) is proposed to effectively suppress the effect of torque harmonics of PMSM on speed fluctuation of the linear feed system at low-speed operation. Firstly, the effect of motor torque harmonics on motor speed for the DDFS is analyzed by the sensitivity function of the servo system, which indicates that the torque harmonics have little effect on the motor speed at high-speed operation. Then, in the DDFS, we make two motors rotate in the same direction at high speed and differentially synthesize at the ball screw to obtain low-velocity linear motion. Compared with the CDFS, the DDFS can suppress the effect of motor torque harmonics on speed fluctuation of the table and improve speed smoothness at low-speed operation.