Complex antenna factor of a V-dipole antenna with two coaxialfeeders for field measurements

In transient field measurements, an antenna with wide band performance both in amplitude and in phase is desired. The complex antenna factor (CAF) is an appropriate characteristic of such an antenna. It is convenient that the CAP of the wide-band antenna is able to be calculated easily. For this purpose, a V-dipole antenna with a balun consisting of two coaxial feeders is investigated. The calculated complex antenna factors are compared with the measured values. The results show that the V dipole has the wide-band performance and the CAF is calculable     

Long backfire antenna with insular image guide feed for dual frequency operation

A long backfire antenna using an insular image waveguide feed compatible with microwave dielectric integrated circuit technology is presented. The antenna operates as a backfire component from 9.7 to 9.9 GHz and as an endfire antenna from 8.9 to 9.9 GHz, with symmetrical radiation patterns and low crosspolarisation. The important parameters of the antenna are experimentally optimised to give a maximum gain of 20 dB and 17 dB when working as a backfire and endfire antenna, respectively. This type of antenna can find extensive applications at millimetre-wave frequencies.     

Antenna Effective Aperture Measurement With Backscattering Modulation

A scattering measurement method for antenna characterization is described. The antenna backscattering is modulated by an oscillator circuit. The modulation begins, when a known RF power is transferred to the oscillator circuit from the antenna. This enables the measurement of the effective aperture of the antenna, from which the antenna bandwidth and radiation pattern are obtained. A theory for antenna aperture measurement is developed using a simple circuit model for the antenna-oscillator system. A dipole and a PIFA with a reactive input impedance at the application frequency were measured. The antenna aperture was measured to an accuracy of 9%, and the measurements complied with simulated and measured references. The method provides simple and accurate bandwidth and radiation pattern measurements with the reactive load the antenna is designed to work with.     

一种机载UHF 频段小型化宽带全向天线设计

机载的安装环境对机载设备的尺寸和重量提出了更高的要求。全向天线是近距离空间链路信号传输的有效技术手段,设计一种机载重量轻、小型化的全向天线具有非常重要的现实意义。区别于传统马刀天线,所设计的天线在尺寸、重量上得到了很大的缩减;为了满足共形要求,天线采用了微带形式,2 mm 的剖面能够根据载体的具体形式进行共形设计;采用双臂组合单极子形式进行阻抗加载,天线实现了超过50% 的驻波带宽(驻波小于2. 5)。通过测试,天线样机的实测性能与仿真结果吻合很好。     

适用于5G通信的宽带毫米波MIMO天线的设计

针对当前5G通信要求的高速率,提出了一种加载水平条形枝节和蝶形寄生单元的倒L型偶极子宽带MIMO天线。该天线以具有不完全地板的倒L型偶极子天线为辐射主体,加载水平条形枝节有效拓展了天线带宽,在天线上端加载一个蝶形寄生单元,有效提升了天线增益;最后将两个天线单元正交摆放,得到了MIMO天线的最终结构。对天线进行仿真与优化,最终结果表明,天线相对带宽达到40.9%(23.1~35 GHz),工作频带内的隔离度均小于-19 dB,带内增益为5.3~7.13 dBi。与引文其它天线相比,目标天线尺寸较小,具有较宽的频带和较高的增益,同时具有良好的隔离度和定向性。天线实测结果与仿真结果基本吻合,验证了其研究与应用价值。     

Analysis of the characteristics of a polyconic antenna in a wide frequency band

A new type of the omnidirectional in the horizontal plane ultra-wideband antenna—a symmetric polyconic antenna—is proposed. Two design versions of the antenna are considered: (i) an antenna with hollow polycones and an antenna with polycones and flat bases. The finite-element method is used for modeling and optimization of the antenna parameters aimed at obtaining the maximum frequency band of matching an antenna with specified overall dimensions and a 50-Ω coaxial line. The integral-equation method is used to study the antenna patterns in a wide frequency band. The results of numerical modeling are compared with the results of a physical experiment.     

Stacked quasi-elliptical patch array with circular polarisation

A simple stacked subarray antenna with circular polarisation is presented. The antenna is based on a quasi-elliptical patch antenna fed with a 45deg offset microstrip line and a circular patch stacked on top of it via an air substrate. The single-element circularly polarised antenna is sequentially rotated into a four-element synchronous subarray resulting in improvement in antenna performance in terms of impedance bandwidth, gain and axial ratio. The antenna is experimentally verified and the results are reported     

Experiments on injection locking of active antenna elements foractive phased arrays and spatial power combiners

Two types of active antenna elements have been studied experimentally. One type uses a microstrip antenna with an active device mounted directly on the antenna. The other uses an active device coupled to a microstrip patch antenna through an aperture. Microstrip active antenna elements and two-element arrays have been demonstrated for both types of circuits. Injection locking of the antenna elements has been achieved through space and mutual coupling. The circuit Q factor was calculated based on the locking gain and the locking bandwidth. The power output from two elements has been successfully combined in free space with a combining efficiency of over 90%. For a single active antenna with a Gunn diode mounted directly on the patch, an electronic tuning range exceeding 9% has been achieved by varying the DC bias. The results should have many applications in low-cost active arrays, active transmitters, and spatial power combiners     

Millimetre-wave InP antenna for monolithic integration

A printed antenna realised on an indium phosphide wafer is presented. The antenna provides an efficient, broadband antenna solution for MMIC/OEIC systems and subsystems. The antenna is based on an aperture coupled patch architecture with the substrates layers in a hi-lo configuration. Measured results exhibit an impedance bandwidth of around 12% for VSWR<2, and a gain of 8 dBi.     

A wide-band monopolar plate-patch antenna

A new design of a monopolar plate-patch antenna is proposed and experimentally studied. The proposed antenna is a planar rectangular monopole top-loaded with a shorted square or circular patch, which is shorted to the antenna ground by two ground plates placed symmetrically on each side of the planar monopole. Prototypes have been constructed and experimental results show, that with an antenna height less than 10% of the free-space wavelength of the center operating frequency, the proposed antenna can have a monopole radiation pattern with an impedance bandwidth larger than three times that of a corresponding monopolar wire-patch antenna.     

Microstrip reflectarray antenna with offset feed

The authors derive and verify the concept of antenna focusing by a planar 'microstrip reflectarray' antenna. Experimental results from schematically distributed patch radiators with microstrip delay lines are consistent with the simulation results. The advantages and disadvantages of such an antenna are described. The measured overall antenna efficiency is approximately 48% at scan angles up to 30 degrees . These results demonstrate the feasibility of such an antenna.<>     

K波段宽带螺旋天线设计

从理论上分析了螺旋天线的设计原理,利用阿基米德螺旋天线实现了一款K波段的高频宽带螺旋天线,使高频天线拥有更轻的质量,更低的剖面及更好的圆极化性。最后通过仿真软件CST设计了一款带宽覆盖18.0~26.5GHz的阿基米德螺旋天线,涵盖了整个K波段。结果表明,该天线在整个频段电压驻波比<2,能很好的满足天线收发要求。     

小型化定向中波天线阵的设计

为了实现定向中波天线阵的小型化,采用现代专业电磁仿真软件FEKO,对常规的中波T型天线进行改进和优化设计使其达到小型化,并以此为天线单元,进行三单元组阵,采用不等幅、不同相馈电技术,从而实现定向中波天线阵的小型化设计,具有一定的工程应用前景。     

Design Method of a Circularly‐Polarized Antenna Using Fabry‐Pérot Cavity Structure

A Fabry‐Pérot cavity (FPC) antenna producing both high‐gain and circularly‐polarized (CP) behavior is proposed. To increase antenna gain and obtain CP characteristics, a superstrate composed of square patches with a pair of truncated corners is placed above the linearly polarized patch antenna with an approximately half‐wavelength distance from the ground plane at the operating frequency. The proposed antenna has the advantages of high gain, a simple design, and an excellent boresight axial ratio over the operating frequency bandwidth. Moreover, used in an FPC antenna, the proposed superstrate converts a linear polarization produced by a patch antenna into a circular polarization. In addition, the cavity antenna produces left‐hand circular‐polarization and right‐hand circular‐polarization when a patch antenna inside the cavity generates x‐direction and y‐direction polarization, respectively. The measured and simulated results verify the performance of the antenna.     

Near fields of a linear antenna

The near fields of a strip antenna in free space have been computed by modifying a variational-impedance formulation. Current distributions, which vary linearly with distance near the ends of the antenna, excite strong tangential electric fields on the antenna surface. Such surface fields are avoided by choosing the axial antenna current to vary in proportion to the square root of the distance from the antenna ends. This modification of the antenna current is not necessary, however, for field calculations at distances comparable to the antenna width. The fields parallel to the antenna surface decrease with increasing distance from the antenna near the driving point and the antenna ends, but are found to increase in an intermediate range.     

Novel small-size directional antenna for UWB WBAN/WPAN applications

This paper presents a novel small-size directional antenna design for ultrawide-band wireless body area networks/wireless personal area networks applications. The design is based on a typical slot antenna structure with an added reflector in order to achieve directionality. The effects of different antenna parameters and human body proximity on the radiation characteristics are analyzed. Antenna measurements with an optic RF setup were performed in order to characterize the small-size antenna far field radiation pattern. The different structural antenna parameters were optimized via extensive numerical simulations. Results show that for frequencies above 3.5 GHz, where the power front-to-back ratio of the directional antenna is greater than 10 dB, its impedance is nearly the same as in the free space. It is not the case neither for the omnidirectional slot antenna nor the monopole antenna next to the body. Between 3 and 6 GHz performance of the novel directional antenna, in terms of radiation efficiency and SAR values, is significantly improved compared to omnidirectional antenna designs.     

Functional antenna integrated with relative humidity sensor using synthesised polyimide for passive RFID sensing

A new type of antenna with an RH (relative humidity) sensing function using a modified polyimide is proposed for passive RFID sensing. Designed to operate at a frequency that depends on the relative humidity level, the proposed antenna is a passive device that physically and functionally combines an antenna with an RH sensor. The compactness and cost-efficiency of the antenna enables it to realise a passive tag of the RFID sensing without an additional sensor component     

A diversity antenna for very small 800-MHz band portable telephones

A diversity antenna comprising a short whip antenna top loaded with a small cylinder and a new built-in antenna has been developed for very small portable telephones in the 800-MHz band. Wire-grid analyses and whip antenna experiments yielded good radiation characteristic results when the equivalent electrical length of the whip antenna equalled a half wavelength. The built-in antenna features extreme compactness, its size being one-third that of a conventional planar inverted-F antenna. The characteristics were investigated experimentally, and an antenna of 3.5 cc volume with a gain of -1 dBd and a bandwidth of 30 MHz was designed at 879 MHz. Finally, the diversity characteristics were subjected to field measurements and a diversity correlation of 0.26 was obtained     

Features of formation of the patterns of a monopulse active phased array antenna with a dome lens

A method for the control of the transmission coefficients of antenna elements of a system comprising an active phased array antenna (APAA) and a dome lens, which ensures formation of a deep boresight null of the elevation difference pattern, is proposed. The effect of the control method on the characteristics of receiving monopulse channels of the APAA depending on the intrinsic noise of antenna elements is analyzed. The results of the well-known theory of reception of a nonplane wave by an antenna with continuous aperture are extended to the case of an array antenna.     

Intra-chip wireless interconnect for clock distribution implementedwith integrated antennas, receivers, and transmitters

A wireless interconnect system which transmits and receives RF signals across a chip using integrated antennas, receivers, and transmitters is proposed and demonstrated. The transmitter consists of a voltage-controlled oscillator, an output amplifier, and an antenna, while the receiver consists of an antenna, a low-noise amplifier, a frequency divider, and buffers. Using a 0.18-μm CMOS technology, each of these individual circuits is demonstrated at 15 GHz. Wireless interconnection for clock distribution is then demonstrated in two stages. First, a wireless transmitter with integrated antenna generates and broadcasts a 15-GHz global clock signal across a 5.6-mm test chip, and this signal is detected using receiving antennas. Second, a wireless clock receiver with an integrated antenna detects a 15-GHz global clock signal supplied to an on-chip transmitting antenna located 5.6 mm away from the receiver, and generates a 1.875-GHz local clock signal. This is the first known demonstration of an on-chip clock transmitter with an integrated antenna and the second demonstration of a clock receiver with an integrated antenna, where the receiver's frequency and interconnection distance have approximately been doubled over previous results