This paper proposes a new approach to further improving the bandwidth of a typical aperture-coupled stacked microstrip antenna by cutting triangular notches in the radiating sides of both radiating patches together wi...This paper proposes a new approach to further improving the bandwidth of a typical aperture-coupled stacked microstrip antenna by cutting triangular notches in the radiating sides of both radiating patches together with offsetting both patches. An antenna applying this new approach is designed,fabricated,and tested. The experimental antenna could achieve a measured impedance bandwidth of about 37.5% for the Voltage Standing Wave Ratio(VSWR) ≤ 2in X-band.展开更多
In this paper, we present a broadband quasi-Yagi antenna. Good impedance matching is obtained by using parasitic elements. The antenna has been designed and successfully measured. Experimental results show that the 10...In this paper, we present a broadband quasi-Yagi antenna. Good impedance matching is obtained by using parasitic elements. The antenna has been designed and successfully measured. Experimental results show that the 10 dB return loss bandwidth of this antenna is 50% operating from 2.3 GHz to 3.8 GHz. We obtain very flat gain (around 5 dB) over the entire bandwidth. For the design and optimization of antennas, we use HFSS CAD software from ANSOFT.展开更多
In order to meet the urgent needs in wireless communications, microwave image synthetic aperture radars （SAR）, and electronic warfare systems, this dissertation studies several types of broadband dual-polarized plan...In order to meet the urgent needs in wireless communications, microwave image synthetic aperture radars （SAR）, and electronic warfare systems, this dissertation studies several types of broadband dual-polarized planar antenna elements and arrays, and proposes a few of novel designs with experimental verification. The main accomplishments reported in the dissertation are as follows.展开更多
In order to broaden the bandwidth of a microstrip patch antenna,a broadbandtwo-port feedingtechnique based on the principle of reactance compensation is suggested.The principle and some designguidelines are presented;...In order to broaden the bandwidth of a microstrip patch antenna,a broadbandtwo-port feedingtechnique based on the principle of reactance compensation is suggested.The principle and some designguidelines are presented;the calculating model of a practical configuration as well as its parameteroptimization is demonstrated,followed by several kinds of test models With their experimental results.It isshown that this technique enables the VSWR bandwidth to be broadened to 2—3 or more times that of aconventional design for both linear and circular polarization operation.展开更多
Phase gradient metasurfaces（PGMS） offer a fascinating ability to control the amplitude and phase of the electromagnetic（EM） waves on a subwavelength scale, resulting in new applications of designing novel microwav...Phase gradient metasurfaces（PGMS） offer a fascinating ability to control the amplitude and phase of the electromagnetic（EM） waves on a subwavelength scale, resulting in new applications of designing novel microwave devices with improved performances. In this paper, a reflective symmetrical element, consisting of orthogonally I-shaped structures, has been demonstrated with an approximately parallel phase response from 15 GHz to 22 GHz, which results in an interesting wideband property. For practical design, a planar antenna is implemented by a well-optimized focusing metasurface and excited by a self-designed Vivaldi antenna at the focus. Numerical and experimental results coincide well. The planar antenna has a series of merits such as a wide 3-d B gain bandwidth of 15–22 GHz, an average gain enhancement of 16 d B, a comparable aperture efficiency of better than 45% at 18 GHz, and also a simple fabrication process. The proposed reflective metasurface opens up a new avenue to design wideband microwave devices.展开更多
This paper, using the frequency bandwidth, where both the gain and the VSWR (Voltage Standing Wave Ratio) of a monopole can satisfy the design requirement, as object function, mainly descr...This paper, using the frequency bandwidth, where both the gain and the VSWR (Voltage Standing Wave Ratio) of a monopole can satisfy the design requirement, as object function, mainly describes the process, in which the load locations, the matching network topology and their component values are optimized by the AGA (Adaptive Genetic Algorithm), to achieve a gain more than -2 dB in horizontal direction and a VSWR less than 3 in bandwidth as wide as possible. Moreover the design results are presented for monopoles with two concentrated loadings. It shows that the AGA is an effective method for designing wideband antennas.展开更多
We propose a cascaded plasmonic nanorod antenna for large broadband electric near-field enhancement. The structure has one big gold nanorod on each side of a small two-wire antenna which consists of two small gold nan...We propose a cascaded plasmonic nanorod antenna for large broadband electric near-field enhancement. The structure has one big gold nanorod on each side of a small two-wire antenna which consists of two small gold nanorods. For each small nanorod, the enhanced and broadened optical response can be obtained due to the efficient energy transfer from its adjacent big nanorod through strong plasmonic near-field coupling. Thus, the electric field intensity of the cascaded antenna is significantly larger and broader than that of the individual small two-wire antenna. The resonant position, field intensity enhancement, and spectral width of the cascaded antenna are highly tunable by varying the geometry of the system. The quantum efficiency of the cascaded antenna is also greatly enhanced compared with that of the small antenna. Our results are important for the applications in field-enhanced spectroscopy.展开更多
Based on the symmetry of the structure, a two-dimensional finite difference time domain （FDTD） method is used to analyze the sleeve monopole antenna on the infinite perfect conductor ground fed by a coaxial line. Th...Based on the symmetry of the structure, a two-dimensional finite difference time domain （FDTD） method is used to analyze the sleeve monopole antenna on the infinite perfect conductor ground fed by a coaxial line. The fields in time domain are then turned into frequency domain through the discrete Fourier Transform to compute the surface current distribution and the input impedance of the sleeve monopole antenna. The gain or pattern of the monopole antenna is also computed, employing the combination of the image theory and the near-to-far transformation in frequency domain. All the computed results agree very well with the results of other methods and measured ones, verifying the application of the FDTD method to analyze the sleeve monopole antennas. The voltage standing wave ratio （VSWR） of the sleeve monopole antennas with different heights and radii of the sleeve are checked to study the influence of the sleeve, which indicates that the height and the radius of the sleeve are both important to the impedance bandwidth of the sleeve monopole antennas.展开更多
文摘This paper proposes a new approach to further improving the bandwidth of a typical aperture-coupled stacked microstrip antenna by cutting triangular notches in the radiating sides of both radiating patches together with offsetting both patches. An antenna applying this new approach is designed,fabricated,and tested. The experimental antenna could achieve a measured impedance bandwidth of about 37.5% for the Voltage Standing Wave Ratio(VSWR) ≤ 2in X-band.
文摘In this paper, we present a broadband quasi-Yagi antenna. Good impedance matching is obtained by using parasitic elements. The antenna has been designed and successfully measured. Experimental results show that the 10 dB return loss bandwidth of this antenna is 50% operating from 2.3 GHz to 3.8 GHz. We obtain very flat gain (around 5 dB) over the entire bandwidth. For the design and optimization of antennas, we use HFSS CAD software from ANSOFT.
文摘In order to meet the urgent needs in wireless communications, microwave image synthetic aperture radars （SAR）, and electronic warfare systems, this dissertation studies several types of broadband dual-polarized planar antenna elements and arrays, and proposes a few of novel designs with experimental verification. The main accomplishments reported in the dissertation are as follows.
文摘In order to broaden the bandwidth of a microstrip patch antenna,a broadbandtwo-port feedingtechnique based on the principle of reactance compensation is suggested.The principle and some designguidelines are presented;the calculating model of a practical configuration as well as its parameteroptimization is demonstrated,followed by several kinds of test models With their experimental results.It isshown that this technique enables the VSWR bandwidth to be broadened to 2—3 or more times that of aconventional design for both linear and circular polarization operation.
基金Project supported by the National Natural Science Foundation of China(Grant No.61372034)
文摘Phase gradient metasurfaces（PGMS） offer a fascinating ability to control the amplitude and phase of the electromagnetic（EM） waves on a subwavelength scale, resulting in new applications of designing novel microwave devices with improved performances. In this paper, a reflective symmetrical element, consisting of orthogonally I-shaped structures, has been demonstrated with an approximately parallel phase response from 15 GHz to 22 GHz, which results in an interesting wideband property. For practical design, a planar antenna is implemented by a well-optimized focusing metasurface and excited by a self-designed Vivaldi antenna at the focus. Numerical and experimental results coincide well. The planar antenna has a series of merits such as a wide 3-d B gain bandwidth of 15–22 GHz, an average gain enhancement of 16 d B, a comparable aperture efficiency of better than 45% at 18 GHz, and also a simple fabrication process. The proposed reflective metasurface opens up a new avenue to design wideband microwave devices.
文摘This paper, using the frequency bandwidth, where both the gain and the VSWR (Voltage Standing Wave Ratio) of a monopole can satisfy the design requirement, as object function, mainly describes the process, in which the load locations, the matching network topology and their component values are optimized by the AGA (Adaptive Genetic Algorithm), to achieve a gain more than -2 dB in horizontal direction and a VSWR less than 3 in bandwidth as wide as possible. Moreover the design results are presented for monopoles with two concentrated loadings. It shows that the AGA is an effective method for designing wideband antennas.
基金Project supported by the National Natural Science Foundation of China(Grant No.11704416)the Hunan Provincial Natural Science Foundation,China(Grant No.2017JJ3408)
文摘We propose a cascaded plasmonic nanorod antenna for large broadband electric near-field enhancement. The structure has one big gold nanorod on each side of a small two-wire antenna which consists of two small gold nanorods. For each small nanorod, the enhanced and broadened optical response can be obtained due to the efficient energy transfer from its adjacent big nanorod through strong plasmonic near-field coupling. Thus, the electric field intensity of the cascaded antenna is significantly larger and broader than that of the individual small two-wire antenna. The resonant position, field intensity enhancement, and spectral width of the cascaded antenna are highly tunable by varying the geometry of the system. The quantum efficiency of the cascaded antenna is also greatly enhanced compared with that of the small antenna. Our results are important for the applications in field-enhanced spectroscopy.
基金Supported by the National High Technology and Development Program of China(2001AA631050)
文摘Based on the symmetry of the structure, a two-dimensional finite difference time domain （FDTD） method is used to analyze the sleeve monopole antenna on the infinite perfect conductor ground fed by a coaxial line. The fields in time domain are then turned into frequency domain through the discrete Fourier Transform to compute the surface current distribution and the input impedance of the sleeve monopole antenna. The gain or pattern of the monopole antenna is also computed, employing the combination of the image theory and the near-to-far transformation in frequency domain. All the computed results agree very well with the results of other methods and measured ones, verifying the application of the FDTD method to analyze the sleeve monopole antennas. The voltage standing wave ratio （VSWR） of the sleeve monopole antennas with different heights and radii of the sleeve are checked to study the influence of the sleeve, which indicates that the height and the radius of the sleeve are both important to the impedance bandwidth of the sleeve monopole antennas.
