Multi-circular loop monopole antenna

A novel multi-band multiple circular loop monopole antenna is presented. The three outer loops have a size ratio of 2 while the feed monopole is a disc, resulting in a quasi-log periodic performance. A method for controlling the radiation pattern, which gives better results than the circular disc monopole at higher operating frequencies, is presented. The proposed antenna performance is also compared with that of the fractal Sierpinski gasket monopole     

The radiation pattern of a monopole antenna attached to aconducting box

A system investigation was undertaken to determine the radiation patterns of a monopole antenna mounted on a cubical conducting box over a ground plane. The effects of the location of the monopole and the electrical size of the box were noted as compared to similar patterns measured over a flat ground plane. Experimental results were also compared with numerically predicted values obtained from a method of moments patch code. It was concluded that the location at which a monopole antenna is mounted on a conducting box and the electrical size of the box clearly affect the overall radiation pattern of a monopole antenna. In general, mounting the antenna away from the center of the box will increase the depth of the nulls     

Folded-type rectangular loop antenna with tunable circuit

A design for a small and tunable loop antenna is presented. This design enables the higher-order mode resonant frequency to become low while keeping the radiation pattern in good shape. The use of a tunable circuit to utilise higher-order mode for bandwidth enhancement has been investigated. The measured and simulated radiation patterns and voltage standing wave ratio are given.     

Simple reconfigurable antenna with radiation pattern

A radiation pattern reconfigurable antenna is proposed. By controlling the switch states, the antenna can be worked as a monopole antenna with an omnidirectional radiation pattern or a dipole antenna with reflector, which has directional radiation pattern. Detailed design considerations of the proposed antenna, simulated and experimental results are presented and discussed.     

Dual band folded monopole/loop antenna for terrestrialcommunication system

With the introduction of DCS1800 to meet the demands for a wider frequency spectrum for mobile communication systems, novel antenna structures capable of generating dual resonance are in demand. An antenna structure based on the geometry of a bent folded monopole antenna capable of dual resonance frequencies operation is discussed. This antenna is able to cover the GSM/DCS 1800 communication system bands     

小尺寸折叠伞锥天线的辐射特性研究

研究了一种短波段新型小尺寸折叠伞锥天线的空间辐射特性,讨论了E面方向图空间俯仰角域的辐射抑制特性,给出了空间辐射场的计算结果.结果表明:所提出的新型天线结构,尺寸小,在宽频带范围内能有效抑制天线的天波辐射.为特殊用途的短波宽带导航天线的设计奠定了基础.     

Single feed antenna with radiation pattern diversity

A vehicle diversity antenna system comprising a single-fed element together with a loaded parasitic element is described. Different termination loads on the parasitic element give rise to variations in the radiation patterns that are comparable with a four-element diversity system. There was good agreement between measured parameters and simulations.     

Double rectangular meander line loop monopole antenna for miniaturisation and bandwidth

The aim of this reported work was to achieve miniaturisation of an antenna for a wireless mic system covering the 216-224 MHz band. A double rectangular loop structure using a meander line was applied for size reduction and the broad bandwidth of the antenna. As a result of the installation of the mic, a length reduction ratio of 91.3% at 221 MHz and -10 dB bandwidth of 9.85 MHz (4.45%) were obtained.     

Combined polygonal loop antenna with circularly polarised conical pattern

A new type of low-profile antenna arrangement is introduced for producing an omnidirectional conical pattern of circularly polarised radiation, and named the combined polygonal loop antenna (CPLA). The maximum gain of 4 dBi is obtained at about 40 degrees off broadside, where cross-pol discrimination is more than 10 dB. Over a frequency range of 16% the radiation pattern remains almost unchanged and the input VSWR is lower than 2.0.<>     

Investigation of characteristics of planar leaky-wave antenna arrays designed for broadside radiation

The results of computer simulation and experimental investigations of new planar leaky-wave antenna arrays designed for microwave and EHF bands and for the mode of radiation normal to the aperture plane have been presented. These arrays comprise single-layer shielded dielectric waveguides and metal-strip periodic diffraction gratings. The specified antennas ensure the radiation efficiency of no less than 50% and the gain of about 28–30 dB within the 3–4% frequency band.     

Broadband RFID tag antenna with quasi-isotropic radiation pattern

A passive RFID tag antenna in the UHF band using two bent dipoles and a modified double T-matching network is proposed. The antenna was fabricated with a thin copper layer printed on a 50 /spl mu/m-thick PET substrate for low-cost production. The proposed antenna provided a quasi-isotropic radiation pattern and a fairly broad bandwidth S/sub 11/<-10 dB, 8.5%) for conjugate-matching with a commercial tag chip. The efficiency of the antenna was about 90% in the operating frequency band. The measured readable range was between 170 -240 cm for an arbitrary rotation angle of the tag.     

双阻带特性的超宽带单极子天线设计

设计了一种具有双阻带特性的超宽带单极子天线,对嵌入开路微带谐振器和边缘相似谐振器进行了分析.利用这两种谐振器可以分别在Wimax（3.33～6 GHz ）和WLAN（ 5.15～5.85 GHz）两个频段产生阻带.通过改变天线几何尺寸,可以分别对阻带的中心频率和带宽独立控制.天线利用印刷线路板（PCB）技术加工实现,并对其阻带特性、回波损耗、辐射方向图、辐射效率和峰值增益进行了测试,测试结果和仿真结果吻合很好.     

Fractal-shaped switched-beam antenna with reduced size and broadside beam

A switched-beam antenna with reduced size and broadside beam based on the fractal Butler feeding network and fractal patch antenna array is proposed. The circuit sizes of the fractal-shaped branch-line couplers, 0 dB crossovers, and patch antennas, are 43.7, 50.1 and 74% smaller than their conventional counterparts, respectively. A four-beam prototype has been constructed. Measurement indicates that broadside beams with sidelobes below 210 dB are achieved.     

Novel radiation pattern reconfigurable antenna with six beam choices

This article presents a novel radiation pattern reconfigurable antenna with six beam choices,which works in 5.2 GHz wireless local area network (WLAN) frequency band.The designed antenna has good imped...     

Dual-band monopole antenna with shorted parasitic element

A printed dual-band C-shaped monopole antenna with a shorted parasitic element is proposed. The proposed antenna can provide two separate impedance bandwidths of 156 MHz (about 6.4% centred at 2.45 GHz) and 2048 MHz (about 37% centred at 5.5 GHz), making it easily cover the required bandwidths for wireless local area network (WLAN) operation in the 2.4 GHz band (about 3.4% bandwidth required) and 5.2/5.8 GHz bands (about 13% bandwidth required). Furthermore, the proposed antenna shows a low-profile of 635 mm above the ground plane. Details of the proposed antenna design and experimental results are presented and discussed.     

Transient radiation field of a circular loop antenna

For a circular loop antenna excited by a frequency-hand-limited rectangular voltage pulse, the time variation of the electric field at remote points in various directions has been computed. The computations are for a loop of radiusbmade from wire of radiusa, for which the thickness parameterOmega = 2 ln (2pi b/a) = 15. The moment method was used in obtaining the current distribution on the loop due to each harmonic component in the excitation. Then the transient field is obtained by using the harmonic current distribution due to each frequency component of the exciting voltage pulse.     

Two-stage Parany monopole antenna with triangular complements

A new multiband and broadband antenna based on the traditional fractal equilateral Parany monopole is presented. In general, Parany and Sierpinski monopoles are resonant, log-periodic and multi-band antennas. For example, a traditional two-stage Parany monopole antenna provides three bandwidths. In this Letter, the input impedance behaviour of this antenna is improved by adding two conductor triangles to a traditional two-stage Parany monopole and eliminating two connections between the conductor triangles that shape such an antenna. For VSWR<3, the resultant fractal two-stage Parany monopole antenna with triangular complements shows bandwidth improvements compared to the traditional two-stage Parany monopole antenna. Good agreement between simulated and measured results was observed.     

Dual reflector antenna with narrow broadside beam for omnidirectional coverage

A new type of high gain omnidirectional antenna is presented, particularly suited for higher frequencies (e.g. millimetre waves): it is obtained with an axially symmetric dual reflector system, fed with an unconventional feed with conical pattern. The feed radiated field, after reflection on the parabolic subreflector and on the conical main reflector, is uniformly scattered in the plane perpendicular to the axis of the system, with vertical polarisation and narrow vertical beamwidth.<>     

Optically transparent monopole antenna with high radiation efficiency manufactured with silver grid layer (AgGL)

A technology based on a meshed silver/titanium bilayer printed on glass substrate is briefly presented. A sheet resistance equal to 0.054 /sq with 81.3 of optical transparency is obtained. The performances of a monopole antenna made from such a material have been investigated. The measured S₁₁ and gain of the transparent antenna are compared with those of an antenna fabricated from a reflective silver/titanium film, and stand for reference. The transparent antenna provides radiation efficiency better than 85%.     

Theory of double parasitic loop counterpoise antenna radiation patterns

Concepts of ray optics and the results of Sommerfeld's half-plane diffraction theory are applied to obtain theoretical expressions for the elevation plane radiation field produced by double parasitic loop counterpoise antennas. Theoretical results are compared with results obtained from model measurements. Within the range of approximation the agreement between theory and experiment has been found to be satisfactory. A method of designing the antenna for special application to air traffic control systems is also discussed briefly.