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This paper presents our study on a single-offset parabolic reflector antenna operating at 220 GHz, which offers high gain as well as the capability of beam steering for longdistance high-capacity terahertz wireless communications. With a switch-controlled array placing on the offset focal plane as the primary feed, the beam steering can be realized by selecting single element in different position...
A comprehensive study of 220GHz waveguide power divider has been presented in this paper, which includes a E-Y junction and a H-Y junction power divider. This research is developed for THz multi-channel array application, such as passive imaging system, aerospace remote sensing system, etc. Both the E-plane and the H-plane power divider shows the great simulation performance from 170GHz to 260GHz...
The quasi-optical network (QON) system generally requires that it has a feature of multi-frequency and multi-polarization for transmitting or receiving more channels in a small space to reduce the satellite load. The wire grid polarizer (WGP) can be mainly used into separating double different signals with horizontal polarization or vertical polarization. Due to its frequency irrelevant attribute,...
This paper presents our study on image reconstruction algorithms for THz near field scanning systems. Based on the principle of Physical Optics (PO) algorithm, we have proposed and investigated a novel transposed convolution image reconstruction algorithm (TC), in comparison with the back propagation algorithm (BP) in simulation and experiment.
This paper presents our study on a sparse antenna array for 0.22 THz imaging. Based on the effective aperture concept for the design of sparse antenna array, two schemes for high performance THz imaging of a target at distance of 1 m have been achieved in simulation. Then, different schemes of larger array element spacing and mechanical scanning spacing have been investigated to build the relationship...
Aperture usage is one of the most important problem in reflector-based compact antenna test range(CATR). Single reflector CATR provides very low aperture usage, normally 30%, because of the effects of edge diffraction. In order to solve this problem, serrated edges and rolled edges are generally chosen along the reflector's edge to reduce the edge diffraction field inside quiet zone(QZ) of the CATR...
Complex surface conductivity at THz frequencies allowing the propagation of relatively slow plasmonic modes results from the unique electronic band structure of graphene, which is followed by a drastically reduced electrical size of the array unit cell and thereby reconfigurable performance. The reflectarray element based on silicon dioxide substrate and Boron Nitride substrate has been developed...
We proposed a novel Doppler effect based microwave frequency mixer which mixes the incident wave with its Doppler shifted signal, instead of a local oscillator. The Doppler shifted signal originates from an effective moving reflective surface built inside the mixer. This kind of mixer can be low-cost without local oscillators, meanwhile the intermediate frequency is tunable electronically.
This paper presents our studies on the scanning schemes deployed in a THz holographic imager. A fast angular beam scanning method is proposed and investigated, in comparison with the existed slow raster scanning method. The performance of both approaches are studied in simulation and partially evaluated in experiment.
A wideband circularly polarized (CP) antipodal curvedly tapered slot antenna (ACTSA) based on waveguide is presented in this paper. By employing the ridge on the broadwall of the slotted waveguide, the antenna can obtain compact structure. The proposed antenna can achieve a bandwidth of 20.8% (56 GHz–69 GHz) for both axial ratio (AR) < 3 dB and reflection coefficient S(1,1) < −10 dB and a gain...
To reduce the radar detection probability of the aircraft during penetration, the sparse A∗ search considering the radar cross section (RCS) distribution characteristic is proposed for route planning. Firstly, the aircraft RCS model and the radar detection probability model are established by considering the attitude and space position of the aircraft. Two kinds of turning modes are studied (the maximum...
A dual-polarized wideband substrate-integrated-waveguide fed aperture-coupled slot antenna array for 60 GHz is proposed. By cutting a semicircle shape on the edge of the crossed-slot antenna, the impedance bandwidth of the proposed antenna is effectively widen and achieves overlapped bandwidth of 16.7% for simulated |S11| and |S22|. In addition, over 35 dB isolation between two polarization and low...
A low cost, simple and compact wideband circularly polarized slotted ground plane antenna design is proposed for mobile terminal. The dual annular perturbation slots antenna with asymmetric stub is built on the grounded substrate. The antenna is design to operate in a wideband that covers 1.85–3.02 GHz frequency band at 10 dB. The circularly polarized radiation patterns have been achieved through...
In this paper, a novel dual band compact antenna based on planar inverted-F antenna (PIFA), ceramic substrate and interdigital coupled structure are proposed. It has compact size with the dimensions of 10.2∗3∗2.5mm3. The operating mechanisms are illustrated and the study on the key dimension parameters is given. Both the simulation and measurement results are shown to verify the good performance of...
In this study, the ultra-wideband (UWB) technique and its capability to detect the cells and layer of a human organs in medical scanning applications has been considered. Advantages and disadvantages of the technique has been highlighted with respect to the capability and accuracy of a medical scanning system especially those using the pulse reflected-based technique. The study contrasts the difference...
This paper presents novel designs, analyses, and simulations of two miniaturised pyramidal double-ridged horn (PDRH) microwave antennas for medical imaging systems. The PDRH antennas have been optimised to operate within a ceramic material filling with permittivity of 41 (which approximately is the permittivity of the human skin in the intended frequency range), in order to make the compact antennas,...
A novel reader antenna based on electromagnetic coupling between three meander open-ended microstrip lines for ultra-high-frequency (UHF) radio frequency identification (RFID) near-field applications is proposed in this paper. Meander line units are introduced to generate a strong uniform magnetic-field distribution over a large interrogation with no null zones. The antenna can be adapted to appropriate...
This paper presents our observation of the abnormal Doppler effect inside a reconfigurable balanced transmission line, which has zero index at the balanced frequency. By applying a digital signal controller, a moving reflective interface is built inside this transmission line. The normal, inverse and zero Doppler effects are observed at different frequencies, which gives a completed picture of Doppler...
This paper presents a wire grid polarizer (WGP) working at the frequency ranges between 1 GHz to 500 GHz. The WGP is extensively used in polarization sensitive elements for separating different polarized signals at the same channel. The spacing pitch-to-width ratio should be chosen seriously for lower cross polarization levels in double polarizers. The influences between single and double layers WGP...
This paper presents our primary work on a THz beam-scanned imager working at 220 GHz. An offset Dragonian dual-reflector antenna is designed to achieve better beam performance during the scanning of the target area. The simulation results show that electrical field amplitude peak values decrease less than 1 dB in the area of 0.4m∗0.4m. And the proposed beam-scanned imaging method is also simulated...
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