共查询到15条相似文献，搜索用时 311 毫秒
1.
综合口径雷达的宽频带双极化口径耦合微带阵 总被引：1，自引：0，他引：1
An 8×1-element wideband dual-polarized slot-coupled microstrip antenna array with high isolation and low cross-polarization in X-band is presented. The array antenna offers an impedance bandwidth (VSWR≤2) of 23% and 21% for dual polarization ports, respectively. The measured isolation between two polarization ports is better than 35 dB and the measured cross-polarization level below -25 dB in the main beam over the operation frequency band of 9.35 GHz to 9.75 GHz. This array is well suitable for X-band SAR (synthetic aperture radar) antenna application. 相似文献
2.
A low-sidelobe circularly-polarized （CP） microstrip patch array for 2.4 GHz radio frequency identification （RFID） readers is presented. The antenna array with a Chebyshev current distribution is composed of 6 microstrip elements. The CP operation is obtained by the quasi-square patch with difference in lengths of the two sides. The antenna has been investigated numerically and experimentally. Measured results show that the array has a Chebyshev pattern with the sidelobe level of -23 dB, the half-power beamwidth of 16° and an impedance bandwidth （S11 ≥-10 dB） of 130 MHz, which is suitable for RFID reader applications. 相似文献
3.
ZHONGShun－shi CUIJun－hai 《上海大学学报(英文版)》2001,5(4):295-298
This paper presents a new design of dual polarized aperture-coupled printed antenna array,The finite-difference time-do-main(FDTD) analysis of an aperture-coupled microstrip element is performed,and the effects of antenna parameters on ist characteristics are obtained to guide the design of the printed array,Then an 8^2 dual polarized array design in X-band is introduced with configuration plots,In order to improve its isolation and cross polarization.an outphase-displacement feeding technique is adopted in the feed network.Also,the round bends are used instead of conventional right-angle bends so as to acieve better VSWR performance,Experimental results are presented.indicating the validity of the design.This dual polarized array can be applied as a sub-array of paceborne SAR systems. 相似文献
4.
This paper proposes a compact polarization microstrip antenna based on double-layer structure.The bandwidth of the whole antenna is widened by expanding the top and bottom layers respectively.After the design of antenna structure and adjustment of size,the proposed antenna can achieve both the left-and right-hand circular polarizations in 2.33 GHz-2.97 GHz.Measurement results indicate that the effective bandwidth is 640 MHz in S-band and the relative bandwidth can achieve 24% with 11 S less than 15 dB. 相似文献
5.
A wideband cavity-backed slot antenna operated in the ultra-high frequency(UHF)band is introduced.The antenna has a compact structure and low profile with the size ratio of the ground plane to the slot only 1.6:1.The measured impedance bandwidth of VSWR≤3 achieves 85.3%,covering a frequency range from 390 MHz to 970 MHz.The measured gain is about 5.5～7.5 dB. 相似文献
6.
This paper presents a novel low-pass filter （LPF） with sharp rejection, wide stopband and compact size, which are realized by the defected ground structure （DGS） and the defected microstrip structure （DMS）. The equivalent circuit model is proposed and the circuit parameters are extracted by the circuit simulation software. The parameters measured are 3 dB cutoff frequency fc of 5.2 GHz, the insertion loss less than 0.5 dB from DC to 4.0 GHz and S21 less than -20 dB within the wide stopband from 6 GHz to 16 GHz. The results of the circuit optimization agree well with those of the full wave simulation and the measured ones, which validate the effectiveness of the equivalent circuit model. The size of the proposed LPF is decreased compared with normal LPF. This LPF can be applied in rectennas to eliminate high order harmonics. 相似文献
7.
A 16×16 micro-strip antenna array with high gain characteristic was proposed for the 5.5 GHz WiMAX application. The T-junctions with a power ratio of 2∶1 were used to design the feed network. To correct the stepped discontinuity of impedance change in common multi-section impedance transformer, exponential line matching transformers were adopted in the WiMAX frequency band. The reflection coefficient was lower than-15 dB from 5.08 GHz to 5.87 GHz. The measured gain of the antenna array achieved 29.8 dBi on E-plane at 5.8 GHz. 相似文献
8.
HUANG Biao YAN Guo-zheng LI Qian-ru 《浙江大学学报(A卷英文版)》2007,8(10):1560-1567
Antenna is very crucial to radiotelemetry capsules which can measure the physiological parameters of the gastroin- testinal (GI) tract. The objective of this paper is to design a novel spiral slots microstrip patch antenna for the radiotelemetry capsules communicating with external recorder at 915 MHz located in ISM (Industry, Science, and Medical) bands. The microstrip patch antenna is designed and evaluated using the finite-difference time-domain (FDTD) method. Return loss characteristics and the effect of the human body on resonant frequency are analyzed, and the performances of radiation patterns at different positions of the human alimentary tract are also estimated. Finally, specific absorption rate (SAR) computations are performed, and the peak 1-g and 10-g SAR values are calculated. According to the peak SAR values, the maximum delivered power for the designed antenna was found so that the SAR values of the antenna satisfy the ANSI (American National Standards Institute) limitations. 相似文献
9.
A zero-dimensional single-zone double-curve model is presented to predict fuel burning rate in stratified charge engines, and it is integrated with GT-Power to predict the overall performance of the stratified charge engines. The model consists of two exponential functions for calculating the fuel burning rate in different charge zones. The model factors are determined by a non-linear curve fitting technique, based on the experimental data obtained from 30 cases in middle and low loads. The results show good agreement between the measured and calculated cylinder pressures, and the deviation between calculated and measured cylinder pressures is less than 5%. The zero-dimensional single-zone double-curve model is successful in the combustion modeling for stratified charge engines. 相似文献
10.
汪伟 《上海大学学报(英文版)》2006,10(3):282-282
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. 相似文献
11.
A compact wideband microstrip array antenna with a squint beam is introduced without the matched load. Its measured beam is
at 10° offset to the broadside with a measured gain of 12 dB at 10 GHz. The measured impedance bandwidth (voltage standing
wave ratio (VSWR)⩽2) is over 16%, which agrees well with the simulated one. It is a low-cost wideband design with compact
simple structure, suited for military and commercial application. 相似文献
12.
INTRODUCTION With the development of modern electronics,there is a growing trend of designing a low-voltagehigh precision current reference in many mixed-signaland analog circuits such as data converters (Mehr andSinger, 2000; Oh et al., 2004), oscillators and PLLs(Razavi, 2001; Banba and Shiga, 1999). Low-costreasons need the reference to be realized in simplestandard CMOS logic process technology, withoutresorting to the use of BiCMOS process and specialdevices such as floating-g… 相似文献
13.
INTRODUCTION Veselago (1968) showed that if both the permit- tivity ε and the magnetic permeability μ of a material are negative, the propagation direction of an elec- tromagnetic (EM) wave will be opposite to its energy flow direction. Such media are called left-handed materials (LHMs) since the electric field E, magnetic field H, and wave vector k in these media form a left-hand triplet of vectors, instead of a right-hand triplet observed in conventional materials. For a long time, … 相似文献
14.
Combining the modified Bethe small holes coupling theory with McDonald thickness theory and field averaging correction factor,
it is accurate to design the weak coupling waveguide directional coupler. While the coupling is tight, the decrease of the
field strength in the main waveguide caused by aperture should not be neglected. For a −6 dB directional coupler is described
in this article, the theoretical value of coupling is good agree to the simulation value, by simulated and optimized with
the professional software computer simulation technology (CST). In the designed waveband, the error of coupling between theoretical
value and simulating one is less than 0.25 dB. The error of coupling between simulation value and designed value is less than
0.5 dB. To improve the isolation, some spaces between two adjacent holes are turned from the traditional ? centre guided wavelength.
The performance of isolation has 5 dB improvement, and length of the coupling area is only 51.06 mm. 相似文献
15.
In order to investigate the physiological effects of airport noise exposure on organisms, in this study, we exposed Sprague-Dawley
rats in soundproof chambers to previously recorded aircraft-related noise for 65 d. For comparison, we also used unexposed
control rats. Noise was arranged according to aircraft flight schedules and was adjusted to its weighted equivalent continuous
perceived noise levels (L
wecpn
) of 75 and 80 dB for the two experimental groups. We examined rat behaviors through an open field test and measured the concentrations
of plasma norepinephrine (NE) by high performance liquid chromatography-fluorimetric detection (HPLC-FLD). We also examined
the morphologies of neurons and synapses in the temporal lobe by transmission electron microscopy (TEM). Our results showed
that rats exposed to airport noise of 80 dB had significantly lower line crossing number (P<0.05) and significantly longer center area duration (P<0.05) than control animals. After 29 d of airport noise exposure, the concentration of plasma NE of exposed rats was significantly
higher than that of the control group (P<0.05). We also determined that the neuron and synapsis of the temporal lobe of rats showed signs of damage after aircraft
noise of 80 dB exposure for 65 d. In conclusion, exposing rats to long-term aircraft noise affects their behaviors, plasma
NE levels, and cell morphology of the temporal lobe. 相似文献