Equal path length design for a phased array antenna system

This work describes the effect of using different shapes of loops with equal electrical path length in antenna miniaturization. Emphasis has been given on equal electrical path length in antenna miniaturization. The loops considered for current antenna topologies are circular, triangular and square keeping the perimeter of loop close to equal in each cases. We have observed the return loss, radiation pattern, input impedance plot, H-field plot, and efficiency for each antenna topology. The reduction in resonant frequency for the cases of circular, triangular and square loops are 22.92%, 22.43% and 36.09%. The reduction is maximum for the case of square loop for better coupling of magnetic field around the square loops in comparison with other loops. Also a huge improvement of −10 dB bandwidth (95.23% to 160.22%) is observed in loaded antennas compare to reference antenna topology. We have also observed that efficiency is in the range of 95.17% to 96.59%. We have compared the simulated results with measured results.

In this brief, a novel combination of multilayer up-down series stacking and multipath architecture for equal path length is explored for the first time to improve the performance of on-chip inductors. The up-down series winding reduces the interlayer capacitance, thereby increasing both the peak quality-factor (Q) frequency ( f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Qmax</sub> ) and self resonant frequency (SRF). The crossover interconnection architecture ensures equal path length at every pair of spiral turns in the series stack. This architecture lowers skin and proximity effect losses in the spiral, increasing the slope of Q characteristics. Thus, using the proposed architecture, both the ac resistance and capacitance are simultaneously reduced while realizing higher inductance values. Implemented in a 0.18 μm high resistivity silicon-on-insulator technology using a dual thick metal stack, the proposed inductor achieves more than 10% improvement in peak-Q value, 50% improvement in f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Qmax</sub> , and 100% improvement in SRF values when compared with a conventional series stacked multipath inductor.

This paper presents the development, fabrication, and measurement of a novel beam-forming system consisting of 16 subarray antennas, each containing four aperture-coupled patch antennas, and the application of this system in smart wireless communication systems. The beam patterns of each of the subarray antennas can be switched toward one of nine zones over a half space by adjusting the specific phase delay angles among the four antenna elements. Furthermore, when all subarrays are pointed at the same zone, slightly continuous beam steering in around 1° increments can be achieved by dynamically altering the progressive phase delay angle among the subarrays. Phase angle calibration was implemented by coupling each transmitter output and down converter into the in-phase/quadrature baseband to calculate the correction factor to the weight. In addition, to validate the proposed concepts and the fabricated 2-D phased array antenna system, this study measured the far-field radiation patterns of the aperture-coupled patch array integrated with feeding networks and a phase-calibration system to carefully verify its spatially switched-beam and beam-steering characteristics at a center frequency of 2.4 GHz which can cover the industrial, scientific, and medical band and some long-term evolution applications. In addition, measured results were compared with calculated results, and agreement between them was observed.

Spherical phased-array antenna has hemispherical scan coverage for transmission of satellite imagery data at high bit rates to the ground station. Different conditions have been assigned based on their effects on the overall performance of the communication link. Reliability analysis consequently becomes an important requirement of any system onboard a satellite. Although the phased array and some connected algorithms have been presented in the literatures; however, there is no extensive systematic and theoretical performance evaluation framework formulated. In this work, the authors present new method that efficiently and effectively analyses the statistical performance of phased-array antenna systems using spherical harmonics expansion approach. Specifically, the errors caused by limited antenna element number, measurement noise of antenna, imprecision in phased-array antenna elements positioning, and spatial aliasing are systematically and theoretically benchmarked via simulations. Spatial sampling mechanisms for the positioning of array antenna elements on a sphere are presented and evaluated. This study proposed design guide and analysis for spherical phased-array antenna systems, and antenna arrays that do not employ spherical harmonics explicitly.

A novel antenna element has been proposed for maritime satellite communication Broadband Global Area Network (BGAN) phased array antenna system. The proposed antenna element is composed of a square radiating patch, two vertical trapezoidal coupling strips and a T-junction power splitter feeding network. A dual orthogonal side coupled feeding technique has been adopted to realize a circularly polarized square patch antenna. Design concepts and procedures are introduced, followed by simulations and discussions. Good antenna characteristics are achieved in the entire BGAN working band, having input impedance match characteristics of S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> <;-15dB, antenna gain higher than 7dBi, and the axial ratio lower than 4dB.

This paper describes a scalable polarization reconfigurable phased array antenna system. The system was realized by using a beamformer and designing a more efficient and flexible power supply and control system, which could be exceedingly helpful to achieve a more flexible ground station design and satellite communication test. As a result, more flexible beam scanning and higher gain could be achieved. The design was simulated by CST Microwave Studio. The complexity of the system was significantly reduced by using the modular design of the active phase control structure.

In this brief, we present a novel multipath parallel-stacked inductor structure that significantly reduces the current crowding effects. Both the metal layers of the parallel stack are divided into multiple segments and crossovers are provided midway of each turn to steer the current in such a way that all its segments have equal path lengths. Following the multipath architecture, prototype inductor structures are fabricated in a 0.18-μm high-resistivity silicon-on-insulator technology using a dual thick metal stack process. Measurements show >30% improvement in quality factor (Q) with the proposed architecture when compared with a standard parallel-stacked inductor. The Q improvement achieved by the proposed inductor structure is shown to increase with the spiral thickness making them suitable for both radio frequency circuits and DC-DC buck converters without having to use magnetic materials. Via resistance is shown to limit the Q improvement possible with proposed inductor configuration.

In this work we report on a novel optical design for beam shaping and focalization of high-power diode laser bars. The goals of our study are: the increase the optical throughput of the beam shaping device with respect to standard solutions and either to enhance the irradiance on a target or to inject the laser beam into a smaller fibre than with respect to beam shaping system based on plane surfaces. The high power diode laser bars pose serious difficulties in their optical handling due to their strong difference between the two transverse axes, which induce a strong astigmatic and asymmetric output radiation. As is well known, the beam quality is very different in the two axes called slow axis and fast axis, and in particular the slow axis is composed by the superposition of several multimodal sources. The beam quality in this axis is very low (its etendue may exceed 2000 mm mrad). On the other hand, the fast axis has a very high beam quality, near diffraction limited, although with very high divergence (30°-50°). The common solution for the application of the laser radiation is a fast axis aspheric micro lens in front of the emitters, in order to achieve its collimation. Typical values of the fast axis collimated beam are 0.7mm and less than 6mrad. However, the so obtained collimated beam is poorly focusable with a standard lens, and a few methods were proposed to overcome the problem. The more relevant solutions include: the stepped mirror technique, the plane parallel mirrors pair, micro prisms array and confocal micro lens array. Each of these techniques is based on the equalization of the beam parameter product by the subdivision of the beam in the slow axis and its reshaping. For all these techniques the efficiency spans from 50% to 70%. The best focalization results allow the coupling in a fibre of 400μm diameter, with NA-0.22. The aim of this work is the design and the realization of a new device, that is considered as target the following aspects: 1) the maximum optical efficiency in the beam shaping process, 2) the optimal equalization of the beam parameter product for the two axes, 3) the use of few optical elements and 4) a very compact size. These goals are addressed by a scheme that splits the collimated beam from the laser diode into different portions while the length of the optical paths of each sub element is kept constant, and by the subsequent use of short focal length aspheric lenses for the focalization of the transformed beam. Each sub-beam is deflected by a couple of plane parallel mirrors, whose normal is directed to equalize the BPP without any mutual shadowing. An optimal solution can be easily envisaged for a laser source of common size of 0.7 x 10 mm. The condition on equal optical path length has the noticeable property of placing the virtual position of the individual portions into which the original beam is split at the same distance with respect to target. Thanks to this, their subsequent focusing is unaffected by the axial displacement of the common solution by the stepped mirrors. In fact, to correct this effect, this latter technique requires the use of a prism pair, involving complexity, size enlargement and higher costs. In this work both an extensive ray tracing and optical analysis is presented as well as the experimental characterization of an experimental model. Moreover, we also report on the technique for the realization of th tilted-face plane mirrors of which is composed our beam shaping device. The scheme of beam shaping here reported can be extended to higher power beam by means of the technique of the beam combination by polarization coupling or that of the optical beam compression. Examples of theses developments are discussed in the paper, and experimental results presented. The most direct applications of the class of optical devices here reported are the high power diode laser direct application in material processing or manufacturing, the coupling into multimode optical fiber of the diode laser radiation as well as the fiber laser end pumping.

Phased array antenna systems, which support high pulse rates and high transmit power, are well suited for radar and large-scale surveillance. Sensors and communication systems can function as the eyes and ears for ballistic missile defense applications, providing early warning of attack, target detection and identification, target tracking, and countermeasure decision. In such applications, active array radar systems that contain solid-state transmitter sources and low-noise preamplifiers for transmission and reception are preferred over the conventional radar antennas, because the phased array radar offers the advantages of power management and efficiency, reliability, signal reception, beam steering target detection. The current phased array radar designs are very large, complex and expensive and less efficient because of high RF losses in the phase control circuits used for beam scan. Several thousands of phase shifters and drivers may be required for a single system thus making the system very complex and expensive. This paper describes the phased array radar system based on high power T/R modules, wide-band radiating planar antenna elements and very low loss wide-band phase control circuits (requiring reduced power levels) for beam scan. The phase shifter design is based on micro-strip feed lines perturbed by the proximity of voltage controlled piezoelectric transducer (PET). Measured results have shown an added insertion loss of less than 1 dB for a phase shift of 450 degrees from 2 to 20 GHz. The new wideband phased array radar design provides significant reduction in size cost and weight. Compared to the conventional phased array systems, the cost saving is more than 15 to 1.

We developed a novel optical coherence tomographic (OCT) system which utilized broadband continuum generation for high axial resolution and a high numeric-aperture (N.A.) Objective for high lateral resolution (<5 micrometers ). The optimal focusing point was dynamically compensated during axial scanning so that it can be kept at the same position as the point that has an equal optical path length as that in the reference arm. This gives us uniform focusing size (<5 mum) at different depths. A new self-adaptive fast Fourier transform (FFT) algorithm was developed to digitally demodulate the interference fringes. The system employed a four-channel detector array for speckle reduction that significantly improved the image's signal-to-noise ratio.

A double-pass interferometer was developed for measuring dimensional changes of materials in a nanoscale absolute interferometric dilatometer. This interferometer realized the double-ended measurement of a sample using a single-detection double-pass interference system. The nearly balanced design, in which the measurement beam and the reference beam have equal optical path lengths except for the path difference caused by the sample itself, makes this interferometer have high stability, which is verified by the measurement of a quasi-zero-length sample. The preliminary experiments and uncertainty analysis show that this interferometer should be able to measure dimensional changes with characteristic uncertainty at the nanometer level.

Section 1 of this paper is a brief review of non-magnetic mass spectrometers and serves as an introduction. Section 2 contains a general theory of radio-frequency ' energy gain : mass spectrometers based on a Fourier analysis of the r.f. analyser field. This method allows a fundamental insight into all energy gain analysers, whether periodic or not and shows that the performance of any analyser is dependent only on the effetive number of stages N. In §3 a comparison is made between the performance of magnetic mass spectrometers and r.f. ' energy gain ' instruments. On the assumption of equal ion path lengths, it is shown that contrary to general belief the current efficiency of the r.f. instruments described in the literature is generally rather less than that of the equivalent magnetic types. A discussion is also given of the factors which limit the resolving power of energy gain mass spectrometers.

The relation between the axial shift and n is not always unique. In milling a single blank with each adjustment of the cutter, decrease in axial shift is accompanied by corresponding increase in n , so long as the tooth wear of the cutter is within permissible limits. However, in milling two or three blanks with each cutter adjustment, n will be proportional to the product of the number of axial shifts and the number of gears machined in each cutter adjustment and will also depend on the nonuniform wear of the cutting teeth. We know that the teeth on the input section of the cutter are subject to more wear. The wear of each tooth in cutting is different. Accordingly, reducing the axial shift to some critical value may entail reduction in the number of gears machined per cutter adjustment so as not to exceed the permissible tooth wear. The number of gears machined over the cutter’s working life may be reduced (since the product of the number of axial shifts and the number of gears machined per cutter adjustment is reduced), even though the number of axial shifts may increase. Conversely, increasing the axial shift to some critical value may increase the number of gears machined per adjustment and hence increase the number of gears machined within the working life. Existing recommendations regarding the axial shift are obtained experimentally or taken from hobbing practice. Thus, recommended values were presented as a function of the tooth inclination and the number of number of gear teeth to be cut, for the standard series of modules (2‐26 mm), in [1]. It was shown that factors significantly affecting the axial shift include the module, the tooth inclination, and the number of tooth to be cut on the gear. However, the discrete values of these factors do not permit the use of these recommendations to determine the rational axial shift of the cutter in other machining conditions [1]. Accordingly, we need to determine the rational axial shift for specific values of the relevant factors. We may use 3D simulation to determine the rational axial shift. As we know, increasing the cutting path length of the cutter tooth or the total volume of metal removed by each tool will increase the cutter wear. Therefore, we have developed a 3D model of tooth cutting that permits accurate determination of both the cutting path length for each cutter tooth and the total metal volume removed by the tooth. On the basis of the simulation, we may sample possible axial shifts so as to determine the value best ensuring equal cutting path lengths for each cutter tooth or equal metal volume removed by each cutter tooth, for the maximum possible number of teeth. This approach to determining the rational axial shift is considered for the example of producing a straighttooth gear using a single-setting cutter. The gear parameters are as follows: height H = 20 mm; module m = 3 mm; number of teeth z 1 = 45. The parameters of the gear cutter are as follows: number of straight chip channels 14; external diameter d a 0 = 112 mm; length of mill’s working section L f = 90 mm; cutting speed v cu = 25 m/min; cutter speed n 0 = 71.05 rpm; axial supply of cutter s ax.c = 2 mm/turn. Each tooth of the cutter is assigned an index n z , which may increase or decrease relative to the symmetry axis of the cutter tooth’s axial profile (with index n z = 0). The symmetry axis of the cutter tooth’s axial profile (with n z = 0) lies in the plane of cutter rotation, passing through the intercenter distance of the cutter and blank.

In this paper, a design of compact W-band planar Quasi-Yagi antenna is presented. The proposed antenna is fed by 50 Ohm coplanar waveguide with a broad-band balun in order to convert from unbalanced grounded-coplanar waveguide (G-CPW) mode into balanced coplanar strip line (CPS) mode. This antenna is realized on a high dielectric constant substrate, GaAs-relative dielectric permittivity of 12.9, that's compatible with active devices and circuits. Using the truncated ground plane as a reflector, the proposed antenna has a broad relative bandwidth of 18.07% with its return loss better than -10 dB, front to back ratio is 15.6 dB and 6.08 dBi of gain at 94 GHz. This antenna can be widely applied in wireless communication systems, active phased array antenna or millimeter-wave imaging systems.

This paper describes the design and implementation of monolithic silicon photonic devices for use in applications such as beamforming and adaptive nulling in phased array antenna systems. Low-loss fixed delay structures and slow-wave variable time delay structures are described.