Current Issue : January - March Volume : 2018 Issue Number : 1 Articles : 7 Articles
A high-temperature superconductor (HTS) microstrip antenna array with right-hand circular polarization is proposed for space\ncommunications. The proposed HTS antenna array can achieve high efficiency, which is able to reduce the antenna�s loss. The array\nconsists of 16 antenna elements being fed by a T-network. A pair of symmetric meander slots is used in each antenna element\nto broaden the input matching bandwidth. A controllable cryostat is used as the refrigeration for HTS. The experiment shows\nthat the gain of the proposed HTS antenna is 8.39 dB, whose 10 dB return loss bandwidth is 2.2% ranging from 5.75GHz to\n5.87GHz. In comparison with a traditional conductor antenna array having the same configuration, the proposed array has an\n8.1 dB improvement in the gain and a 69.2% enhancement in the radiation efficiency....
We propose a wide bandwidth antenna with a circular polarization for universal Ultra High Frequency (UHF) radio-frequency\nidentification (RFID) reader applications. To achieve a wide 3 dB axial ratio (AR) bandwidth, three T-shaped microstrip lines are\ninserted into the ground plane. The measured impedance bandwidth of the proposed antenna is 480MHz and extends from 660\nto 1080MHz, and the 3 dB AR bandwidth is 350MHz and extends from 800 to 1155MHz.The radiation pattern is a bidirectional\npattern with a maximum antenna gain of 3.67 dBi. The overall size of the proposed antenna is 114 Ã?â?? 114 Ã?â?? 0.8mm3....
We propose a model of antenna-coupled microbolometer to be included in an array for receiving and detecting long wave infrared\n(LWIR) electromagnetic radiation. The antenna is joined to microstrip bandpass filters thus forming a single metal structure to\ndefine the operation frequency band. The antenna and microstrip filters are modeled in aluminum thin film. The microbolometer\nis modeled with superconducting niobium, all together on a silicon nitride membrane. The squared pixel structure is designed on\na support frame of 20...
An edge slotted waveguide antenna array based on T-shaped cross-section radiating waveguide is proposed. The T-shaped\nwaveguide is analyzed and designed to operate in dominant mode around the center frequency, which has a lower profile compared\nwith the rectangular one.The radiating slots are etched and rotated alternatively on the broadened top plate without cutting into the\nadjacent walls. The metal fences are inserted between slots to reduce the mutual coupling and surface wave.Therefore, the sidelobe\nlevel in ...
A Gaussian tapered slot antenna based on post-wall structured slotline for improvement of cross-polarization for ultra-wideband\napplications is proposed and experimentally demonstrated.Theantenna is composed of two pairs of Gaussian tapered slotlinewhich\nhave the same structure printed on both sides of the PCB, two metallic via arrays positioned along the slot edges, and two terminal\nresistors.Themetallic via arrays are used to reduce the characteristic impedance of the conventional slotline which forma post-wall\nslotline and thus can be fed by a coaxial connector directly.More importantly, the balanced symmetrical post-wall structure ensures\nlow cross-polarization levels of the antenna. The Gaussian tapered edges and the terminal resistors diminish reflected signal and\nthus can enlarge the bandwidth significantly.Good agreements between the simulated and the measured results have been observed.\nResults show that the proposed antenna exhibits a âË?â??10 dB impedance bandwidth from1.5GHz to 20GHz, a maximum realized gain\nof 12 dBi, and the broadside cross-polarization level is averaged about âË?â??32 dB in the lower frequency band and âË?â??25 dB in the higher\nfrequency band with a maximum value of âË?â??22 dB in the whole working frequency band....
Antenna array-based multi-dimensional infinite-impulse response (IIR) digital beamformers\nare employed in a multitude of radio frequency (RF) applications ranging from electronically-scanned\nradar, radio telescopes, long-range detection and target tracking. A method to design 3D IIR beam\nfilters using 2D IIR beam filters is described. A cascaded 2D IIR beam filter architecture is proposed\nbased on systolic array architecture as an alternative for an existing radar application. Differential-form\ntransfer function and polyphase structures are employed in the design to gain an increase in the speed\nof operation to gigahertz range. The feasibility of practical implementation of a 4-phase polyphase\n2D IIR beam filter is explored. A digital hardware prototype is designed, implemented and tested\nusing a ROACH-2 Field Programmable Gate Array (FPGA) platform fitted with a Xilinx Virtex-6\nSX475T FPGA chip and multi-input analog-to-digital converters (ADC) boards set to a maximum\nsampling rate of 960 MHz. The article describes a method to build a 3D IIR beamformer using\npolyphase structures. A comparison of technical specifications of an existing radar application based\non phased-array and the proposed 3D IIR beamformer is also explained to illustrate the proposed\nmethod to be a better alternative for such applications....
Radio frequency fingerprint (RF fingerprint) extraction is a technology that can identify the unique radio transmitter at the physical\nlevel, using only external feature measurements to match the feature library. RF fingerprint is the reflection of differences between\nhardware components of transmitters, and it contains rich nonlinear characteristics of internal components within transmitter.\nRF fingerprint technique has been widely applied to enhance the security of radio frequency communication. In this paper, we\npropose a new RF fingerprint method based on multidimension permutation entropy. We analyze the generation mechanism of\nRF fingerprint according to physical structure of radio transmitter. A signal acquisition system is designed to capture the signals to\nevaluate ourmethod, where signals are generated fromthe same three Anykey AKDS700 radios. The proposed method can achieve\nhigher classification accuracy than that of the other two steady-state methods, and its performance under different SNR is evaluated\nfrom experimental data. The results demonstrate the effectiveness of the proposal....
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