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A transmissive metasurface polarization beam splitter (MPBS) with three-layer dielectric substrate was designed to meet the application requirements of polarization beam splitting devices. The micr...

A high-resolution near-field focusing metasurface lens (MSL) was proposed to meet the high-resolution and miniaturization requirements of focusing devices in the Ka-band passive millimeter wave (PM...

A novel dual-wideband dual-polarised magnetoelectric (ME) dipole antenna for the fourth generation (4G)/fifth generation (5G) microcell base station is proposed. Using a pair of orthogonal ME dipoles and Γ-shaped tapered cross feeding lines, the initial antenna achieves dual-band and dual-polarised. Then, four U-shaped gaps, added in electric dipoles, effectively extend the lower impedance bandwidth. Finally, a circular parasitic patch with capacitive properties is innovatively loaded above the ME antenna, which obviously reduces the high-resonant frequency from 5.5 to 4.9 GHz. Meanwhile, a box-shaped reflector is employed to achieve stable gain and radiation patterns. As a result, the measured results show the good dual-wideband performance of 52.4% (2.14–3.66 GHz) and 7.4% (4.68–5.04 GHz) with voltage standing wave ratio (VSWR) 25 dB) and high gain (9.5 and 5.5 dBi, respectively). In addition, a stable radiation pattern with a half-power beam width of 63.5 ° ± 6.8 ° and good cross-polarisation discrimination (>20 dB) on the E-plane is realised over these two bands.

In this article, several miniaturized microstrip fifth-order lowpass filters with structure of unit artificial transmission line are presented. Reactive elements including inductors and capacitors are constructed by microstrip structures directly by parameter extraction from electromagnetic simulation. A transmission zero in stopband can be achieved by inductors and capacitors (LC) series-resonant circuit composed by parallel-plated capacitors and connecting lines. Meanwhile, loading interdigital capacitors would bring in another transmission zero. In comparison, fifth-order Butterworth and Chebyshev lowpass filters with one and two transmission zeros are fabricated, respectively, to verify the extra transmission zero effect caused by LC shunt resonant-circuits with interdigital capacitors. The proposed lowpass filters are compact and their sizes occupies less than 40% of conventional microstrip lowpass filters. The simulated and measured results demonstrate good agreements between them, which ver...

In this article, a broadband dual-polarized dipole antenna for mobile communication systems is proposed. The design is based on improvements to conventional bowtie dipole antennas, thereby simultaneously achieving wider bandwidth and a more compact size. The antenna consists of a metallic plate reflector and a pair of orthogonal planar dipoles with U-shaped slots, which are separately excited by T-shaped feeding lines. The application of U-shaped slots and T-shaped feeding lines effectively extends the impedance bandwidth. Additionally, using a new approach of adding metallic cylinders to each dipole improved impedance matching. Experimental results indicated that the designed dual-polarized antenna achieved a notably wide bandwidth (1.58–2.82 GHz). Further, the measured isolation between the two ports was better than 30 dB and cross-polarization level was less than –25 dB on the axis. Moreover, the antenna had stable radiation patterns with half-power beam width of 65° ± 5° on the horizontal plan...

A broadband dual-polarized base station antenna is proposed in this paper. The antenna consists of loop cross-dipoles, Y-shaped coupling feeding lines, and a metal box reflector. An equivalent circuit model including a signal flow diagram is established to analyze the mechanism of the proposed antenna in detail. Moreover, the Y-shaped coupling feeding lines are introduced to control the coupling with the antenna to achieve broadband and good impedance matching. The prototype of the antenna is fabricated and measured. The measured results show that the antenna with simple structures can operate at the band of 3.2&ndash, 5.22 GHz (48%) with high port-to-port isolation (35 dB) and stable gain (9 &plusmn, 1 dBi). The measured results show good agreement with simulated results, especially in cross-polarization discrimination ratio (&gt, 27 dB) and the half power beam width (61&deg, &plusmn, 3&deg, at the E-plane, 68&deg, at the H-plane). In summary, the proposed antenna could be a good candidate for 5G sub-6 GHz base station applications.

A wideband filtering power divider (FPD) with wide rejection bandwidth and good isolation is presented, based on conventional Wilkinson structure. Parallel coupled lines and two pairs of open-circuit stubs are used for achieving bandpass filtering response and enhancing the performance of the rejection bandwidth. Furthermore, by properly choosing two resistors between two pairs of open-circuit stubs allows good isolation performance. Measured results indicate that the FPD operates at 2.35 GHz ( f 0 ) with a − 20 dB bandwidth of 55.3%. In the upper stopband range from 3.7 to 8.8 GHz (3.74 f 0 ), the minimum rejection is 20 dB. Within working band, the isolation between the output ports is higher than 24 dB. In addition, ultra-wide isolation better than 20 dB from DC to 10 GHz is obtained.

A novel wideband dual-polarized printed dipole antenna fed by two integrated feeding networks is presented. The feeding network, a kind of compact halfwave balun, delivers equal amplitude (within 0.1 dB) and 180° (±5°) phase difference between the two output ports from 1.65 to 2.8 GHz. By employing an H-shaped slot in each arm of the dipole, wide impedance bandwidth has been obtained. Experimental results show that the proposed antenna can operate from 1.7 to 2.7 GHz with low voltage standing wave ratios ( 25 dB) and high isolation (>31 dB) are also achieved over the entire bandwidth. Moreover, stable radiation patterns and low back lobes are obtained by using a modified reflector.

The uniformity of optical coatings becomes more and more important as large diameter optical devices are widely used. Absorption loss in optical components, particularly in optical coatings, is a limiting factor in high-power laser applications. This article analyzes the main factors, which affect the spatial resolution of three techniques for surface absorption loss measurement, including the photothermal deflection technique, the surface thermal lens technique, and the photothermal detuning technique. The influence of the size of the heating and probe beam on the photothermal detuning technique is studied in detail. Experiments are conducted to study the photothermal signal of the photothermal detuning technique for absorption measurement of the optical coating point by point. The results show that the main factors, which affect the spatial resolution of imaging measurements for absorption loss of coatings, are the heating beam size and the step accuracy of the sample translation stage. The heating and probe beam sizes has a significant impact on the application of the photothermal detuning technique. Experimental result shows that the photothermal detuning technique can be used for imaging of absorption loss measurements of optical coatings. The results provide theoretical and experimental supports for further application of the photothermal detuning technique.

the concept of plasma antennas array has been put forward for a long time, but the study on the mutual coupling between elements of the array is very little. In this paper, a model for antennas array involving two plasma elements is set up, where the density of element 1 is assumed to be very high and could be used as metal, and the mutual impedance between plasma elements is derived detailedly. Then, considering that the density of the plasma element 2 is uniform or non-uniform distribution, we analyse mutual impedance of the two plasma column antennas which vary with the plasma density, collision frequency inside element 2 and the distance of two elements. The result of experiment shows, under normal circumstance, the amplitudes of mutual resistance and reactance between two plasma antennas are smaller than those between two metallic antennas which has the same configure and size, and the plasma density, collision frequency inside element 2 will impact the impedance. This is very useful for beam forming and directional reconfiguration among of plasma antenna's application.

The sensitive photothermal interferometric detection technique, in which an interference fringe pattern formed by overlapping two reflected probe beams from the front and rear surfaces of the sample with two interfaces was used to measure the photothermal signal, and its application for characterization of transparent (or partially transparent) plate samples had been theoretically and experimentally investigated in detail. Theoretical and experimental results demonstrated the proposed photothermal interferometric detection technique to be a sensitive photothermal method for the study of the thermophysical properties of transparent samples. Can this method be applied to the field of single-layer optical thin film system? We all know that a single-layer optical thin film is usually deposited on a substrate and has three interfaces. In this paper, based on the transmission theory of Gauss-beam, the interference effect of the reflection beams from a single layer film-substrate is studied. A theory is developed to describe the intensity profile of the interference fringe and the corresponded modulated photothermal interferometric signal. An experiment is performed with a ZnS-BK7 glass single-layer sample to measure the intensity distribution of the interference fringe pattern and the photothermal signal with CW laser excitation. Agreement is obtained between the theoretical predictions and experimental results. It shows the photothermal interferometric detection technique can be used to study the thermophysical properties of the single-layer optical thin film system.

When a modulated laser beam irradiates an optical component, the laser-induced surface deformation has both direct current (DC) and alternating current (AC) portions. Explicit surface deformation and surface thermal lens (STL) theory models are developed to describe the DC and AC portions of the surface deformation and corresponding STL signals. Experimentally, a setup combining laser calorimetry (LC) and STL technique is developed to measure the absolute absorptance and laser-induced surface deformation of optical components. The absorptance measurement is implemented by LC with excellent stability and repeatability. The surface deformation measurement is realized with STL amplitude by defining an approximately linear relationship between the AC (or DC) STL amplitude and the maximum AC (or DC) deformation. As an example, the deformation value of a BK7 substrate coated with a TiO2/SiO2 film stack of absolute absorptance 1.32×10 -3 , irradiated by a 1064nm laser with 3.8W power is determined to be 34.3 nm with the experimental STL amplitude, in good agreement with the theoretical value of 35.8 nm calculated by the explicit surface deformation model. An indirect approach is proposed to determine accurately the irradiation beam radius by fitting the experimental data of the radial AC intensity change at the detection plane to the explicit STL model. By performing a theoretical fit to the experimental frequency dependence of the STL amplitude, the thermal properties of the optical component (i.e. the thermal diffusivity) can also be determined.

Absorption loss in optical components, particularly in optical coatings, is a limiting factor in high-power laser applications. The uniformity of optical coatings becomes more and more important as large-diameter optical devices are used widely. In this paper, the photothermal detuning technique used for absorption uniformity measurement of optical thin films is developed for the first time. Experiments are conducted with a highly reflective coating used in 514 nm to measure the photothermal detuning signal and to evaluate the absorption at 514 nm by detecting the spectral shift with a probe beam at a wavelength of 632.8 nm. The relative absorption at different points on the sample surface can be measured by moving the sample two-dimensionally, and we use the measured data to make the absorption image. The results show that the designed experimental system can be used to analyze the absorption uniformity of optical coatings. The obtained images reflect the absorption uniformity of the sample well. The absorption uniformities of the two samples analyzed in this experiment are different. The film coated on fused silica is better. The research provides a powerful and convenient tool for absorption uniformity measurement of optical thin film.