Wideband Scanning Research Articles

A Wideband Compact Printed Dipole Antenna Array With SICL Feeding Network for 5G Application

A wideband compact printed dipole antenna array with an element size of 0.16 λ0 × 0.34 λ0 is proposed for millimeter-wave (mmW) applications, particularly for 5G applications. The two patches of the dipole are printed on two different layers to achieve a wide bandwidth of 50% (24–40 GHz) for SWR <2. Ground-signal-ground transmission line construction with a height difference between the feeding via and the two shorting vias is employed to achieve a relatively symmetrical radiation pattern. An antenna array consisting of the proposed antenna and a 1 to 8 substrate-integrated coaxial line feeding network is fabricated and measured. Simulations are also used to verify the beam scanning performance (up to ±50°). The proposed compact printed dipole antenna is a good contender for 5G mmW applications due to its wide band, compact size, and good beam scanning performance.

A Wideband Scanning Circularly Polarized Array Antenna Based on the Shorted Transmission Line Model

Due to the huge potential of application in the communications, electronic jamming, and radar fields, circularly polarized (CP) array antennas with wide axial ratio (AR) scanning performance at wide frequency bandwidth have received great attention. A wideband scanning CP planar array antenna built by new, tightly coupled dipole array (CP-TCDA) elements, which have achieved promising results in terms of both scanning AR bandwidth and angle range in all scanning planes, is presented in this paper. Based on the shorted transmission line model, a CP-TCDA element arranged along the &#x00B1;45&#x00B0; direction is constructed, which can shift the middle-frequency scanning blind zone out of band and thus obtain a wideband scanning AR bandwidth. Furthermore, the proposed CP-TCDA element adopts four shorting pins and four square parasitic strips, which improve wide-angle CP performance for <i>xz</i>-plane and diagonal-plane scans, respectively. An 8&#x00D7;8 left-handed CP planar array antenna based on the proposed CP-TCDA elements is designed and prototyped. The results show that the array antenna is able to operate over a 3:1 (4&#x2013;12 GHz) overlapping bandwidth, and it meets the requirements of AR &#x003C; 3 dB and active VSWR &#x003C; 2.9 within a &#x00B1;45&#x00B0; scanning angle range.

Design of an S-Band Phased Array with Modified Dipoles

A wideband, low cross-polarization, high-gain, and wide-angle scanning antenna array is presented in this paper. The antenna array contains 8 subarrays in the horizontal dimension, and each subarray contains 4 unit cells. A two-side printed dipole with an amendatory equivalent circuit model is adopted, and the metal vias are introduced in the element design to ameliorate the cross-polarization level. A radome, acting as the wide-angle impedance matching layer, is introduced to achieve wide-angle scanning. A prototype of a 4 × 8 array is fabricated and measured. The results show that the operating bandwidth of aperture efficiency (BWAE) above 60% is about 26.7% from 2.6 GHz to 3.4 GHz. The measured scanning loss in the H-plane is 2.7 dB when scanning up to 60° with active voltage standing wave ratio (VSWR) &lt;3, and the gain can achieve 21 dB at 3 GHz with a cross-polarization level below −30 dB at all angles.

A tightly coupled dipole array used for radiation power improvement on finite radiation aperture

Radiation power of an electromagnetic wave plays a decisive role in its transmission distance. Traditionally, the radiation power can be improved by expanding the radiation aperture size of the antenna array or increasing input power of the unit cell. However, the radiation aperture size is always restricted by assembly space. The input power improvement of the unit cell is always limited by the signal source. It is difficult to improve radiation power on a finite radiation aperture. However, the radiation power on a finite radiation aperture is related closely to the number of antenna elements and the radiation efficiency of the antenna array. It is useful to arrange more elements and improve radiation efficiency of the antenna array to improve the radiation power on a finite radiation aperture. Wideband wide-angle scanning phased array is able to make full use of a finite radiation aperture. The wide-angle scanning properties make it possible for the radiated power to cover a wide area. In this paper, a compact wideband wide-angle scanning tightly coupled dipole array (TCDA) is proposed. A high permittivity substrate and compact wideband balun are used for miniaturizing the antenna array. The period of the unit cell is only 0.144&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;high&lt;/sub&gt; × 0.144&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;high&lt;/sub&gt; (&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;high&lt;/sub&gt; is the wavelength at the highest operation frequency in free space). Parameters of the balun are optimized to improve impedance matching between the balun and the antenna array. Two bilateral frequency selective surfaces (FSSs) are used to replace traditional dielectric superstrate to improve the impedance matching between the antenna array and free space. A low-loss dielectric substrate is used to reduce dielectric loss of the antenna array. In these ways, the radiation efficiency is greatly improved. The simulation results show that the proposed antenna array operates at 1.7–5.4 GHz (3.2:1) while scanning up to 65° in the E plane, 45° in the H plane and 60° in the D plane with following a rigorous impedance matching criterion (active VSWR &lt; 2). A 16 × 16 prototype array is fabricated and measured. Good agreement is achieved between the simulation results and the measurement results. Compared with the designs in the literature, the proposed antenna array has an excellent performance in radiation power on a finite radiation aperture.

A corner truncated fractal slot ultrawide spectrum sensing antenna for wireless cognitive radio sensor network

SummaryDue to the scarcity of the radio frequency spectrum, the emergent network sharing technique elicits the efficient use of licensed unutilized spectrum. Here, an ultra‐wideband (UWB) microstrip antenna is proposed for wireless cognitive radio sensor network (WCRSN). The antenna is uniquely designed for large spectrum scanning of channel vacancies in licensed frequency bands. Software‐defined radios (SDR) govern the algorithmic controls on spectrum sensing and channel interface using an appropriate antenna. The antenna comprises the effects of fractal slot patch and electromagnetic bandgap (EBG) ground structures on 12 × 18 × 1.6 mm3 FR4 (relative dielectric constant of 4.4) substrate. Circular polarization is achieved through corner truncation to make antenna orientation free in wireless sensing networks. The measured |S11| parameter offers 0.75‐ to 12‐GHz wide spectrum sensing with 2.51‐dBi average gain. The antenna is unique in compactness and includes lower edge bands of frequencies (0.75–3.1 GHz) along with UWB (3.1–12.0 GHz) for a very wide range scanning to utilize vacant channel opportunity in WCRSN through SDR. The proposed structure is experimented and validated for real‐time wideband scanning of the frequency spectrum within the operating limit as per the allotted FCC standard.

Multiple‐input‐multiple‐output antenna with pattern reconfiguration and correlation reduction for WLAN applications

AbstractA Yagi‐Uda inspired novel pattern reconfigurable multiple‐input‐multiple‐output (MIMO) antenna array is proposed in this article. The antenna consists of two co‐axially excited microstrip patch radiators with modified ground plane. A conducting strip with an integrated PIN diode is optimally placed midway between two MIMO patch radiators placed at a distance of 0.22 ( is the free space wavelength at 2.4 GHz) apart. By switching the diode OFF or ON, the conducting strip directs or reflects the main beam of the two MIMO elements at an angle of ±30° or ±60°, respectively, thereby, enabling 30° wide band scanning and four switchable beams radiated by the two antennas. The novel MIMO antenna exhibits 17 dB isolation improvement between the two radiators when the diode is switched ON as a result of the beam deflection. For all switching modes, the MIMO antenna demonstrates an average gain and efficiency of 5 dB and 92%, respectively, at the resonance frequency of 2.4 GHz. The novel antenna is fabricated and measured to verify the simulation results. This simple, low‐cost, efficient, and mutually isolated antenna array can be very useful in MIMO WLAN applications.

Linewidth compression of tunable Tm-doped fiber laser and its hyperspectral absorption application

Tunable diode laser absorption spectroscopy (TDLAS) is a widely used technology for measuring absorption spectrum. However, the measurement efficiency of TDLAS is greatly limited by the narrow tuning range of conventional tunable laser diode. Exploiting a wideband, narrow linewidth tuning laser source, hyperspectral absorption spectroscopy possesses the ability to provide the overall absorption information over a continuous waveband in a single scan, which would significantly improve the data volume and diagnostic capability of TDLAS. With profound and strong absorption lines of water and carbon dioxide, the 2 μm waveband is an ideal candidate for water and carbon dioxide related absorption spectrum. An absorption line recognition threshold of 0.07 nm is derived for the absorption spectrum measurement of water around 2 μm through theoretical analysis. Utilizing the wideband emission spectrum of Tm-doped fiber, a wideband tunable, narrow linewidth fiber laser operating at 2 μm is built by combining a tunable FP filter with a fiber saturable absorber. The tunable FP filter is responsible for the wavelength control of the laser system, with which a 60 nm wideband tuning range from 1840 nm to 1900 nm is achieved. With a section of Tm-Ho codoped fiber as the fiber saturable absorber which is used for linewidth compression, a static linewidth of 0.05 nm is attained. This wideband tunable, narrow linewidth fiber laser is tested for the hyperspectral absorption spectrum measurement of water around 2 μm. Drived with a 0–10 V triangle wave at a repetition rate of 50 Hz, the output spectrum of the laser spans over a wavelength range of about 30 nm from 1856 nm to 1886 nm. The laser beam propagates about 50 cm through an open air, and then enters into the detectors for direct measurement. The 35 absorption lines of water are recognized after processing the data. Within the 1870–1880 nm range, comparisons with the theoretical absorption spectra at different laser linewidths, derived from the HITRAN2012 absorption database, show that the measured data cannot effectively distinguish two absorption lines adjacent to the strong absorption line at 1873 nm and 1877 nm. And, the measured results can be best fitted to a laser linewidth of about 0.08 nm, demonstrating that in the dynamic scanning process, the linewidth of the laser is expanded beyond the absorption line recognition threshold. Thus, when operating in a fast wideband scanning mode, the laser system should further compress its linewidth.

UWB dual‐polarised dipole array with dielectric and FSS superstrate and 65° scanning

The authors report the design of an ultra-wideband (UWB), dual-polarised, tightly coupled dipole array (TCDA) with an integrated balun for wide-angle scanning. A dual-pol dipole design enables massive bandwidth, large scanning volume, and high polarisation purity, concurrently. To achieve wide-angle impedance matching without exciting surface waves, two types of superstrates are evaluated on a finite array: (i) dielectric superstrate and (ii) novel planar frequency-selective surface (FSS). The latter architecture is capable of scanning 70° in E- plane and 65° in H- plane and shows, on average, 5° scanning improvement to the former. The impedance bandwidth is 5.25:1 (0.8-4.2 GHz) at the broadside (voltage standing wave ratio (VSWR)<;2). The bandwidth reduces to 4.3:1 (0.9-3.9 GHz) when the maximum scanning angle or θ max increases to 65° for the H -plane and 70° for the E -plane (VSWR <; 3.2). The proposed array is a great candidate for wide-angle wideband scanning applications covering the entire L and S bands.

Do we need all the frequency components of a fringe signal to obtain position information in a vertical scanning wideband interferometer?

Abstract Using a wideband light source based vertical scanning interferometer, we can obtain the position information of an object from the peak value of the envelope of the interference fringe signal. For the reconstruction of the envelope of this signal, it is necessary to select its frequency components; however, the question that naturally arises is whether there is a need to select all the frequency components of the signal to determine the position of the envelope peak. Based on our proposed method and subsequent optical experiments, we find that the peak position of the envelope can be estimated using only the frequency pairs that have high signal-to-noise ratios. Thus, this observation can be applied to not only improve the measurement performance of wideband scanning interferometers, but also to enable more complex and accurate optical metrology.

Determination of cracks in structural materials using the radio spectroscopy method

The new method proposed in this research is based on the spectral registration of the microwave range radiation by means of a wideband scanning receiver. The experiments have proved its accuracy sufficient for the spectrum frequency determination. Sensitivity of 5-6 Hz/nm level is achieved. The obtained spectra are analyzed using a specialized hardware-software complex. The evidence from practice has shown that the method in question, apart from detecting the substances qualitative composition, helps determine the presence and propagation of cracks.

Universal non-destructive testing method in the microwave range

Considered in this paper, a new method of nondestructive control based on the spectra of radio wave radiation of the microwave range wideband scanning receiver. It is experimentally shown that this method has a high accuracy in the determination of the frequency spectrum. This allows the method considered to reach a sensitivity of 5-6 Hz/nm.

Particle swarm optimization of the tapered slot antenna for wideband scanning E-plane linear array

Paper describes a novel way to optimize the unilateral tapered slot antenna (TSA) being an element of a wideband scanning E-plane linear array. Taper profile of the antenna is mathematically represented as a piecewise linear function. Particle swarm optimization algorithm is implemented to find the coordinates of piecewise linear profile following the purpose to minimize the active reflection coefficient of TSA in a scanning array environment. Active reflection coefficient down to −15 dB is theoretically achieved for TSA in E-plane linear array operating over the most part of frequency band 5–10 GHz and scanning sector ±30°. The proposed design approach is validated by experimental investigations of two linear array test samples with fixed main lobe directions at 0° and 30° respectively. Each test sample is composed from eight similar TSA elements with the optimized piecewise linear profile. Arrays are excited by the 8-way microstrip power divider of corporate type with microstrip true time delay lines at the outputs that provide required wideband phasing of radiating elements.

Wideband scanning small linear arrays in presence of mutual coupling

This reported work concerns the wideband performance of small linear uniformly spaced arrays in the presence of mutual coupling when used in beam scanning applications. Optimum pattern bandwidth performance is obtained by implementing a particle swarm optimiser with Schelkunoff's unit circle approach. Performance comparison has been made with a conventional Taylor distribution.

Ultrasonic apparatus and method for evaluation of bone tissue

A method and system (100) for ultrasonic imaging of bone tissue. A wide band scanning crystal (122) transmits an ultrasonic signal of high frequency, and multiple full waves into the bone tissue, and a second wide band scanning crystal (124) receives the transmitted signal. The transmission frequency is progressively decreased until the number of full waves in the received signal equals that of the transmitted signal. At that frequency, the upper frequency limit, the number of full waves in the transmitted signal is gradually increased until the received signal contains at least two consecutive full waves of equal amplitude. The resultant transmission signal is then used to measure signal attenuation, and velocity in bone tissue, in terms of standard bone imaging techniques. A lower frequency limit, below which the received signal undergoes distortion, is defined, and ultrasonic velocity depicted as a function of transmission frequency. Received ultrasonic wave frequency spectra, the difference between the upper, and lower frequency limits, are all used to image the bone tissue.

Constrained feed technique for subarrays of large phased arrays

A technique is presented which combines the subarraying qualities of constrained dual transform beamforming sections and partial overlapping networks to produce arrays of contiguous subarrays. This approach is shown to facilitate wideband scanning or limited field of view coverage with a minimum number of controls and low sidelobes.

Wideband scanning of a guided-light beam and spectrum analysis using magnetostatic waves in an yttrium iron garnet-gadolinium gallium garnet waveguide

Wideband scanning of a light beam through the use of magnetostatic waves has been accomplished for the first time. Specifically, a guided-light beam at a wavelength of 1.317 μm in an yttrium iron garnet-gadolinium gallium garnet waveguide was Bragg diffracted by magnetostatic forward volume waves (MSFVWs) operating at a frequency range of 2–7 GHz. Wideband scanning of the light beam was accomplished simply by changing the frequency of the MSFVW continuously from center frequencies of 2.5 and 6.0 GHz while keeping the dc magnetic field fixed or by continuously tuning the dc magnetic field while keeping the frequency of the MSFVW fixed at the center frequencies. A large number of resolvable scan spot positions were obtained in both cases. The resulting wideband magneto-optic Bragg cell or light beam scanner was also used to perform spectral analysis of wideband rf signals at a center frequency of 3.2 GHz. Potential advantages of the magneto-optic Bragg cell and scanner over the existing acousto-optic counterparts also identified.