Realization of dual-frequency and wide-band VSWR performances usingnormal-model helical and inverted-F antennas

The effects of parasitic elements on the voltage standing wave ratios (VSWR's) of two antennas are investigated. First, a parasitic monopole is used for a normal-mode helical antenna. The VSWR investigation shows that dual-frequency operation is obtained by the parasitic element effects. The dual-frequency operation is revealed as a function of monopole position above a ground plane (monopole height). As the monopole height decreases, the separation of a higher resonance frequency f_H from a lower resonance frequency f_L increases. For a monopole length of L_MP≈0.4λ_HX , where λ_HX is the resonance wavelength of the helix, the frequency bandwidth for a VSWR=2 criterion is 12.5% in the lower frequency f_L region and 5.2% in the higher frequency f _H region, with a frequency separation ratio of f_H/f_L=2.14. Secondly, L-figured parasitic elements are used for an inverted-F antenna (IFA). The parasitic elements improve the VSWR performance. The frequency bandwidth for a VSWR=2 criterion is approximately two times as wide as that of the single IFA. It is also found that bending the horizontal sections of the IFA and parasitic elements contributes to reducing the antenna size while not significantly deteriorating the VSWR bandwidth. The radiation patterns are also presented and discussed     

Bandwidth enhancement of the monopole antenna by using a parasitic normal-mode helix

An innovative monopole antenna coupled with a parasitic normal-mode helix has been designed and studied both experimentally and theoretically. The effects of various dimensions of the monopole and the parasitic helix were investigated extensively. This simple combination can significantly enhance the antenna bandwidth over that of the conventional monopole antenna. It is found that, with suitably chosen antenna dimensions, the VSWR bandwidth (VSWR ≤ 2) of the antenna can be increased to 36%, almost double that of the monopole antenna alone. The far-field pattern of the combined antenna is basically the same as that of the monopole antenna. This antenna is designed to operate at 1.8GHz. The substantially enhanced bandwidth of this simple and small antenna is a useful feature for future mobile communications.     

Planar meander sleeve monopole antenna for DVB-H/GSM mobile handsets

A novel planar meander sleeve monopole antenna for digital video broadcasting-hand held (DVB-H) and GSM mobile handsets is presented. By using the planar sleeve monopole type radiating element constructed with meander strips, the antenna provides a degree of miniaturisation while retaining a wide bandwidth covering the DVB-H and GSM-900 bands. A prototype is constructed and tested, which shows that an impedance bandwidth of 498 MHz (463-961 MHz) within 2.5:1 VSWR is achieved.     

Height-reduced meander zigzag monopoles with broad-band characteristics

The characteristics of a meander dual zigzag wire monopole antenna are described. The antenna provides low height and broad-band performance. Measured voltage standing-wave ratio (VSWR) and pattern characteristics are compared with a conventional, straight-wire monopole over a 3:1 bandwidth.     

Broadband dual frequency sleeve monopole antenna for DTV/GSM applications

A broadband dual frequency sleeve monopole antenna for application in digital television (DTV) systems and global system for mobile communications (GSM) is presented. A parasitic inverted L-shaped strip and dual planar sleeve structure are introduced in the back ground plane for expanding the frequency band. The simulated and measured results show that the impedance bandwidth covers the DTV (470? 862 MHz) band and GSM (824?960 and 1710?2170 MHz) band with VSWR less than 2.5. An omnidirectional radiation property is also shown.     

Broadband planar antenna with parasitic radiator

A novel kind of planar monopole broadband antenna with a parasitic radiator is presented. Measurements show that the bandwidth of the monopole antenna has been considerably improved with a parasitic element earthed with a matching inductor. The achieved impedance bandwidth reaches over 85% for VSWR/spl les/2, and the measured radiation patterns have little distortion when the frequency changes. The impedance bandwidth parameters are compared for different dimensions of ground planes     

Design and realization of GA-optimized wire monopole and matching network with 20:1 bandwidth

This paper presents the successful design and physical realization of broadband loaded wire monopoles with matching networks. The loads are parallel inductor/resistor circuits that are adjusted by means of genetic algorithm (GA) optimizers to maximize bandwidth, and the matching networks are transmission-line transformers. The micro-GA is shown to be more convenient and efficient for optimizing these loaded antenna systems than is the simple-GA. The measured voltage standing-wave ratio (VSWR) of the loaded antennas confirm broadband performance and agree with data obtained from moment method computations. Antennas having bandwidth ratios of 12.6 : 1 and 18 : 1, with measured VSWR less than 3.5 and calculated system gain greater than -4.5 dBi, are presented. Finally, an antenna system is given that has measured VSWR less than 3.0 and calculated system gain greater than -3.2 dBi over a 20 : 1 band.     

Multiple meander strip monopole antenna

A novel multiple meander strip monopole antenna is presented. By iteratively meandering the vertical strip, compactness and broadband characteristics for the monopole antenna were achieved simultaneously. The designed monopole antenna with a radiation element volume of 14/spl times/14/spl times/14 mm/sup 3/ has the measured bandwidth ratio of 3.87:1, from 2.83 to 10.96 GHz for VSWR/spl les/2, with fairly frequency-insensitive omni-directional radiation characteristics.     

Wide-band planar monopole antennas

The circular disc monopole (CDM) antenna has been reported to yield wide-impedance bandwidth. Experiments have been carried out on a CDM that has twice the diameter of the reported disc with similar results. New configurations are proposed such as elliptical (with different ellipticity ratios), square, rectangular, and hexagonal disc monopole antennas. A simple formula is proposed to predict the frequency corresponding to the lower edge of the bandwidth for each of these configurations. The elliptical disc monopole (EDM) with ellipticity ratio of 1.1 yields the maximum bandwidth from 1.21 GHz to more than 13 GHz for voltage standing wave ratio (VSWR)<2     

Printed annular monopole antenna for ultra-wideband applications

A novel printed monopole antenna for ultra-wideband applications is introduced, which consists of an annular monopole patch and a trapeziform ground plane with a tapered CPW feeder in the middle. The simulated and experimental results demonstrate that this antenna achieves a ratio impedance bandwidth of more than 10:1 for VSWR/spl les/2, and exhibits the nearly omnidirectional radiation pattern with a simple structure.     

Elliptical slot loaded partially segmented circular monopole antenna for super wideband application

This article inspects partially segmented circular monopole with elliptical slot for super wideband applications. Two significant characteristics of proposed antenna design are: (i) partially segmented circular monopole, notch loaded elliptical ground plane along with tapered microstrip line provides super wide bandwidth; (ii) elliptical slot in between the partially segmented circular monopole reduces the lower operating frequency (1.07 GHz–0.96 GHz), which in turn enhance the bandwidth dimension ratio (BDR). For verifying the simulated outcomes, antenna prototype is practically constructed and measured. The proposed antenna design attains frequency range from 0.96 GHz to 10.9 GHz (VSWR < 2) with bandwidth ratio of 11.35:1 and percentage bandwidth of 167.22%. Bandwidth dimension ratio of proposed radiator is 6975.22. Frequency as well as time domain analysis of proposed radiator approves its applicability for super wideband wireless applications.     

快速精确分析套筒单极子天线的一种实用新方法

本文利用矩量法分析计算套筒天线.文中采用一种新的粗圆柱线天线快速精确计算模型,提出了所谓的"等长分段"方法,并使用了一种固定间隔电压源模型,大大提高了分析计算的精度;通过使用正弦插值基函数、引入Daubechies小波变换等,提高了分析计算的速度.最后,设计制作了一付工作在200-700MHz频段、VSWR≤3.0的实用套筒天线,其分析计算结果与实验结果相吻合.     

An experimental study of a balun-fed open-sleeve dipole in front of a metallic reflector

The characteristics of a balun-fed open-sleeve dipole mounted in front of a metallic reflector for operation in the 225 to 409 MHz band are investigated. A parametric study is made of the VSWR response as a function of dipole and sleeve diameter, sleeve length, and sleeve-to-dipole spacing. It is shown that an open-sleeve dipole can be operated over a bandwidth of 1.8:1 as compared with an operating bandwidth of approximately 1.25:1 for a conventional cylindrical dipole with the same diameter. Pattern and gain data are presented for an open-sleeve dipole mounted in front of a flat metallic reflector. Preliminary results on mutual coupling effects are also discussed.     

A backfire helical feed

A novel backfire helical feed for a paraboloidal reflector is described. The antenna requirements were a 20 percent bandwidth atL- band, right-hand circular polarization, a maximum voltage standing-wave ratio (VSWR) of 2.0, and a peak power capability of 200 kW unpressurized. The feed consists basically of a 3.5-turn helix wound around a1frac{5}{8}-in rigid coaxial transmission line. The50 Omegatransmission line is coupled to the helix through a two-stage transformer within the coax followed by a half-wave coax to two-wire (unequal diameters) balun.     

Ultra-Wideband Design of the Wire Conical Antenna

Using the wire construction technique, a conical monopole antenna is fabricated. With the method of moments, the dependences of the voltage standing wave ratio （VSWR） on the number of the trapezoid wire elements, conical angles, wire radius, etc. are investigated. The calculation and the experiment show that the designed wire conical antenna has the ultra-wideband property and can be used for the engineering.     

Elliptical planar monopole antenna with extremely wide bandwidth

A planar monopole antenna with an extremely wide bandwidth is introduced, which is composed of an elliptical monopole patch and a trapeziform ground plane, both printed on the same side of a substrate, and is fed by a tapered CPW feeder in the middle of the ground plane. The simulated and experimental results demonstrate that this antenna achieves a ratio impedance bandwidth of 21.6:1 for VSWR/spl les/2, and exhibits a nearly omnidirectional radiation pattern, while its area is only about 0.19/spl lambda//sub l//spl times/0.16/spl lambda//sub l/ where /spl lambda//sub l/ is the wavelength of the lowest operating frequency.     

Broadband quasi-taper helical antennas

A unique approach is described for widening the bandwidth of a helical antenna with improved gain, pattern, and axial ratio characteristics. The antenna may be described as a nonuniform or quasi-taper helix, which consists of a combination of uniform and tapered helix sections. Measured patterns, gain, axial ratio, and VSWR for various helical antenna configurations are presented and compared. It is shown that a nonuniform quasi-taper helix can provide an operating bandwidth twice that of a conventional uniform-diameter helix.     

Synthesis method for broad-band tapered wire antennas and itsexperimental verification

A method for synthesizing the geometry of extremely broadband tapered wire antennas used as part of a broadband spectrometer for millimeter and submillimeter waves is presented. The antenna is designed to have a nearly constant gain and a low voltage standing-wave ratio (VSWR) over a bandwidth of at least 20:1. After the synthesis, the characteristics of the antenna are analyzed by the moment method using a system of reaction integrals as described by Richmond (1974). An antenna version with resistively loaded ends of the wires has a mean gain of 5.7 dBi and a maximum gain variation of ±1.25 dB. The VSWR is equal to 1.7 over almost the entire frequency range peaking only to 2.6 at the lowest frequency. These theoretical results were verified by measurements in the frequency range from 1 to 18 GHz with a scaled model of the tapered wire antenna     

Small-size printed CPW-fed antenna for ultra-wideband communications

A novel printed monopole antenna fed by a coplanar waveguide (CPW) is proposed in view of ultra-wideband applications. Its impedance bandwidth defined by a voltage standing-wave ratio (VSWR , 2) is from 3 to 11.3 GHz with a fractional bandwidth of 116%. A parametric study of the proposed antenna was carried out in order to optimise the main parameters. Details of the proposed antenna design and measured results are presented and discussed.     

Compact printed monopole antenna with 24:1 impedance bandwidth

A compact tapered CPW-fed hollowed elliptical printed monopole antenna with extremely wide bandwidth is proposed. The results demonstrate that this antenna achieves a measured impedance bandwidth from 0.44 to 10.6 GHz (24.1:1) for VSWR les 2, and exhibits a nearly omnidirectional radiation pattern, while its area is only about 0.18 times 0.13lambda_l, where lambda_l is the wavelength of the lowest operating frequency.