共查询到20条相似文献,搜索用时 31 毫秒
1.
New design of a circular microstrip antenna with dual capacitively coupled feeds for broad-band circular polarization radiation is presented. The dual feeds are with a small top-loaded disk and are connected to a Wilkinson power divider with a 90° phase shift between its two output feedlines. The radiating circular patch, printed on a thin substrate, is supported by nonconducting posts on a conducting ground plane and is excited capacitively through the dual feeds. With a distance less than 10% times the center operating wavelength between the circular patch and the ground plane, the present proposed antenna can provide an impedance bandwidth (VSWR ⩽2) of about 49% and a 3-dB axial-ratio bandwidth of about 35%. The antenna gain bandwidth, defined to be within 1-dB gain variation in the axial-ratio bandwidth, is as large as 28%, with the antenna gain level at about 7.0 dBi 相似文献
2.
Ka Wai Chan Kin Fai Tong Kwai Man Luk 《Electronics letters》1999,35(24):2070-2071
The characteristics of a circular patch microstrip antenna with a top-loaded monopole feed are investigated. Air is used as the dielectric substrate. The distance between the radiating patch and ground plane is ~0.15λ0. The patch is excited in the TM01 mode. An impedance bandwidth (SWR<2) of 50% and an average gain of 5dBi are obtained 相似文献
3.
《Antennas and Propagation, IEEE Transactions on》2010,58(1):35-42
4.
Experimental results for U-slot circular patch antennas with L-probe feeding are presented. Using a foam layer of thickness ~0.1λ0 as a supported substrate, an impedance bandwidth of 38% (SWR⩽2) and a gain of 6.8 dBi have been achieved. The far-field radiation patterns are stable across the passband 相似文献
5.
Experimental results for L-probe proximity-fed short-circuited quarter-wavelength patch antennas are presented. Using a foam layer of thickness ~0.1λ0, as a supported substrate, an impedance bandwidth of 39% and a gain of >7.0 dBi have been obtained. The far field patterns are stable across the passband 相似文献
6.
A new half-hemispherical dielectric resonator antenna (h-HDRA) is proposed and a two-element h-HDRA configuration is employed to design a broadband monopole-type radiator. Two half sections of a hemispherical DRA are employed to enhance the impedance bandwidth by introducing an additional resonant mode. Since the new geometry of an h-HDRA is studied here for the first time, it is characterized using simulation and experimental studies. Two closely spaced resonant modes, which in a two-element h-HDRA generate monopole-type radiation are investigated. Results for both the single and two-element h-HDRAs are presented. As much as 35% impedance bandwidth (S11<-10dB) with more than 5 dBi peak gain, 99.08% efficiency and monopole-type radiation pattern has been demonstrated using a prototype occupying a compact volume measuring 0.48lambda0 by 0.2lambda0 approximately, lambda0 being the wave length corresponding to the center of the impedance bandwidth 相似文献
7.
A dielectric resonator antenna formed by a U-shaped dielectric resonator and a conformal elliptical patch feed is proposed for wideband communication applications. Simulated results agree well with measured ones, showing good performance in terms of bandwidth and radiation patterns. The measured impedance bandwidth of S11 < -10 dB is about 72%, covering the frequency range 3.82-8.12 GHz. It has a gain of 4.3-7.6 dBi over the whole operating band with a ground size of about 1.2 lambda0 times 1.2 lambda0, lambda0 being the central operating frequency. 相似文献
8.
Nakano H. Shinma Y. Yamauchi J. 《Antennas and Propagation, IEEE Transactions on》1997,45(10):1506-1511
A monofilar spiral antenna is analyzed in the presence of a conducting plane reflector, using the method of moments. The circumference of the spiral antenna is chosen to be 2.3 wavelengths. A tilted beam of circular polarization is realized by superposing the fields from two active regions. The gain of the tilted beam is approximately 8 dB. The frequency bandwidths for 1-dB gain drop and 3-dB axial ratio criterions are 12% and 23%, respectively. An array consisting of the four monofilar spiral antennas is also analyzed, where the array element spacing is chosen to be 0.8 wavelength at a design frequency f0. The input impedances of the four spirals are almost the same as the impedance of the single monofilar spiral antenna at f0. The array radiates a tilted fan beam with a gain increase of approximately 6 dB from the gain of the single spiral antenna at f0. The frequency bandwidth for a 3-dB axial ratio criterion is almost the same as that of the single spiral antenna 相似文献
9.
Guo Y.J. Paez A. Sadeghzadeh R.A. Barton S.K. 《Antennas and Propagation, IEEE Transactions on》1997,45(1):177-178
A TM02-mode circular patch antenna for the application of radio LANs is reported. An experimental prototype operating at 5.2 GHz is designed and tested. The antenna pattern is omnidirectional in azimuth and has a notch in the normal direction. A 3.3% bandwidth of VSWR ⩽2 and 4.2-dB antenna gain were measured. Experimental results agree well with theoretical predictions 相似文献
10.
A broad-band rectangular patch antenna with a pair of wide slits 总被引:4,自引:0,他引:4
Kin-Lu Wong Wen-Hsis Hsu 《Antennas and Propagation, IEEE Transactions on》2001,49(9):1345-1347
A new broad-band design of a probe-fed rectangular patch antenna with a pair of wide slits is proposed and experimentally studied. The proposed design is with an air substrate, and experimental results show that, simply by inserting a pair of wide slits at one of the radiating edges of the rectangular patch, good impedance matching over a wide bandwidth can easily be achieved for the proposed antenna. With an air substrate of thickness about 8% of the wavelength of the center operating frequency, the proposed antenna can have an impedance bandwidth of about 24%. For frequencies within the impedance bandwidth, good radiation characteristics are also observed, with a peak antenna gain of about 7.2 dBi 相似文献
11.
Ming-Chou Chiang Shey-Shi Lu Chin-Chun Meng Shih-An Yu Shih-Cheng Yang Yi-Jen Chan 《Solid-State Circuits, IEEE Journal of》2002,37(6):694-701
The realization of matched impedance wide-band amplifiers fabricated by InGaP-GaAs heterojunction bipolar transistor (HBT) process is reported. The technique of multiple feedback loops was used to achieve terminal impedance matching and wide bandwidth simultaneously. The experimental results showed that a small signal gain of 16 dB and a 3-dB bandwidth of 11.6 GHz with in-band input/output return loss less than -10 dB were obtained. These values agreed well with those predicted from the analytic expressions that we derived for voltage gain, transimpedance gain, bandwidth, and input and output impedances. A general method for the determination of frequency responses of input/output return losses (or S11, S22) from the poles of voltage gain was proposed. The intrinsic overdamped characteristic of this amplifier was proved and emitter capacitive peaking was used to remedy this problem. The tradeoff between the input impedance matching and bandwidth was also found 相似文献
12.
13.
A Dual-Polarized Magneto-Electric Dipole With Dielectric Loading 总被引:1,自引:0,他引:1
A plusmn45degdual-polarized magneto-electric dipole loaded with dielectric substrate is presented. This antenna is composed of shorted-circuited patches and planar dipoles and is fed by four Gamma-shaped probes. The height of a prototype antenna operated at 1.9 GHz is only 24 mm (0.15lambdao). A wide impedance bandwidth of 24.9% is achieved. The average gain is about 8.2 dBi and the isolation between the two ports is higher than 29 dB over the operating bandwidth. It is demonstrated that the antenna performance can be improved by adding metallic side walls. 相似文献
14.
Bin Li Kwok Wa Leung 《Antennas and Propagation, IEEE Transactions on》2008,56(2):353-359
A differentially fed rectangular dielectric resonator antenna (DRA) is studied using the finite-difference time-domain (FDTD) method. The fundamental TE111 mode of the rectangular DRA is excited at 2.4 GHz, with a 10-dB differential impedance bandwidth (|Sdd11| < -10 dB) of ~10.4%. To verify the theory, measurements were carried out, and reasonable agreement between theory and experiment is obtained. The effects of the magnitude and phase imbalances on the DRA impedance and radiation pattern are investigated. 相似文献
15.
Wee Kian Toh Zhi Ning Chen 《Antennas and Propagation Magazine, IEEE》2008,50(2):95-105
A design concept for elevating suspended-plate radiators is presented in this paper. The proposed antenna comprises two radiators connected by a folded feeding structure. The folded structure suppresses the occurrence of higher-order modes when the height of the antenna is elevated beyond 10% of the free-space wavelength, lambda0 . The broadband radiating mechanism is explained. Both the simulation and measurement results show that a consistent gain of 7.2 dBi to 8.5 dBi is achieved over a frequency range of 2.3 GHz to 3.6 GHz, namely within a 44% impedance bandwidth for |S11|< -10 dB. The concept is used to design two cost-effective broadband antennas covering both WLAN and WiMAX operations. 相似文献
16.
A curved spiral antenna above a finite hollow conducting cylinder is analyzed using the method of moments. The effects of cylinder length 2H and cylinder radius rcy on the radiation characteristics of the spiral are evaluated. As 2H increases, the cross-polarization component of the radiation field in the broadside direction decreases to a constant value (approximately -18 dB). When 2H is greater than one wavelength (λ0), the input impedance of the spiral above a cylinder of radius rcy=0.25 λ0 is almost constant (250-j20 Ω) with a gain of approximately 7 dB. The spiral above a cylinder of (2H, rcy)=(2.7 λ0, 0.25 λ0) shows a 3-dB axial ratio bandwidth of approximately 23%, which is wider than a flat spiral antenna above a flat ground plane of infinite extent 相似文献
17.
Karmakar N.C. Hendro P. Firmansyah L.S. 《Microwave and Wireless Components Letters, IEEE》2003,13(1):13-15
RF switches are integrated to the shorting straps of a single feed dual-band planar inverted-F antenna (PIFA) to make a tunable PIFA. The L-band switch yields 0.45-dB insertion loss (IL) and 10-dB isolation bandwidth (BW) of 40% at 1.5 GHz. The tunable PIFA yields 39% impedance BW at 900-MHz band and 7.8% BW at 2000-MHz band. The measured radiation patterns are nearly omni-directional and yield a gain of -7.8 dBi at 652 MHz and 4.3 dBi at 2104 MHz. 相似文献
18.
A proposal of broad-bandwidth vertical-cavity laser amplifier 总被引:2,自引:0,他引:2
We propose a generic vertical-cavity amplifier (VCA) using a coupled-cavity design to broaden the bandwidth. Calculations are made for cavities with GaAs-AlAs and GaAs-AlxO2 distributed Bragg reflectors (DBR). We found that at reasonable pumping levels the VCA increased the bandwidth by 85% (GaAs-AlAs) to 500% (GaAs-AlxO2) as compared to a simple two-mirror structure similar to vertical-cavity surface-emitting lasers. In particular, the GaAs-AlAs VCA shows a bandwidth of 2 nm at 6-dB signal gain, while the GaAs-AlxO2 VCA demonstrates a 5-nm bandwidth at 6-dB signal gain with no ripple at required single-pass power gain of ~2-2.5%. Furthermore, as large as 30-nm bandwidth in a lossless bandpass filter can be obtained 相似文献
19.
提出了一种采用非均匀频率选择表面(frequency selective surface, FSS)盖板以及非均匀电磁带隙(electromagnetic band gap, EBG)结构反射地板的高增益Fabry-Perot(F-P)谐振腔天线. 基于漏波理论模型,针对大口径F-P谐振腔天线设计非均匀的FSS盖板和EBG反射地板,控制衰减常数α和相位常数β,改善了口径场上幅度相位分布的均匀性,并抑制了非谐振频率时天线辐射性能的恶化,实现高增益和高口径效率的同时,保证了天线的工作带宽. 所提出的圆形F-P谐振腔天线直径为6.6λ0,仿真增益为24.6 dBi,口径效率达67.9%,阻抗带宽为4.1%,3 dB增益带宽为3.7%;实测增益为23.9 dBi,口径效率达56.9%. 由于对口径场均匀性的设计,该天线克服了传统F-P谐振腔天线的口径效率和增益间的相互限制. 相似文献
20.
Two novel Marconi-Franklin type printed antenna arrays, each consisting of three radiating elements arranged in a cascade configuration, are investigated. Both antennas are printed on a single high permittivity dielectric substrate and fed by SMA connectors, although coplanar waveguide (CPW) feed could easily be applied to further allow easier integration into an RF chip module. Two constructed prototypes, suitable for local-multipoint-distribution service operation in the 26-GHz band (25.5-26.5 GHz), are demonstrated. The constructed prototypes show an impedance bandwidth of about 1 GHz and a maximum gain of more than 5 dBi, with small variations (<1.8 dBi), is obtained across the achieved impedance bandwidth. Details of theoretical and experimental results showing impedance and radiation characteristics for both prototype antennas are given and discussed. 相似文献