Dual slot-coupled microstrip antenna for dual frequency operation

A new dual slot-coupled circular antenna for dual frequency or dual polarisation operation is proposed. By optimising the placement of the two slots, high isolation between two ports is achieved. Experimentally, an isolation of more than 35 dB is obtained at L-band.<>     

小地板锯齿作馈源的背射式天线

本文提出一种新式宽带线极化背射天线。该天线的馈源是一种背射式锯齿天线。这种背射天线E面和H面主瓣宽度在 2 6°～ 39°之间 ;其方向图和驻波系数等主要指标带宽可达 1～ 1.6。此外这种天线还具有馈电方便、结构简单等优点。     

Slot antenna with parasitic element for dual band operation

The authors introduce three types of dual band antenna combining a slot and a parasitic wire. The slot and the parasitic wire are designed to become resonant at two different bands. The antenna characteristics are calculated by the method of moments; calculated VSWRs are in good agreement with measured data     

Long rectangular patch antenna with a single feed

Radiation characteristics of a long rectangular patch antenna excited by a single feed are investigated. The equivalent circuit of the patch including the feed line section is developed. It is found theoretically that a single feed long rectangular patch supports a leaky traveling wave along the length of the patch. The complex propagation constant of the traveling wave is estimated by solving the wave equation with impedance boundary conditions. Radiation patterns of the antenna are obtained using the principle of equivalence. Various radiation characteristics of center-fed and end-fed long patch antennas are presented     

Broadband dual frequency microstrip antenna

A new dual port microstrip antenna geometry for dual frequency operation is presented. The structure consists of the intersection of two circles of the same radius with their centres displaced by a small fraction of the wavelength. This antenna provides wide impedance bandwidth and excellent isolation between its ports. The gain of the antenna is comparable to that of a standard circular microstrip antenna operating at the same resonant frequency. A theoretical analysis for calculating the resonant frequencies of the two ports is also presented     

Dipole-excited short backfire antenna with corrugated RIM

This letter reports results of an experimental study at X-band of a dipole-excited short backfire antenna having corrugations on the main reflector rim. The results obtained show that the presence of the corrugations can lead to improved antenna gain and sidelobe levels.     

Rectangular backfire antenna with dielectric surface-wave structure

A rectangular backfire antenna with a dielectric surface-wave structure is studied experimentally and theoretically. It consists basically of two plane rectangular reflectors and a dielectric structure as a rectangular-waveguide prolongation. The antenna construction is compared with those of ordinary dielectric and horn antennas, which are more than twice the length of the backfire antenna. Simple expressions for the far-field radiation pattern are derived in terms of the near-field amplitude distribution.     

Rectangular-waveguide-excited short backfire antenna with corrugated rim

The letter presents experimental results at X-band for a short backfire antenna with corrugated rim, which is excited by a rectangular waveguide. It is shown that the use of the waveguide feed can lead to a compact antenna having a directive gain of 20dB, sidelobe levels of ? 17 dB and v.s.w.r. in the range 1.1?2.     

Tapered backfire helical antenna with loaded termination

In order to improve the radiation characteristics of a backfire bifilar helical antenna, a means of terminating the arm ends with a resistor is numerically and experimentally investigated. Owing to the reduction of reflected current, the present backfire helix realises an excellent front-to-back ratio and axial ratio, while maintaining inherent absolute gain.     

Single layer printed monopole antenna for dual ISM-band operation

The ability of a single layer strip fed printed monopole, which has a serial-slot and an end-stepped feed-strip, to operate at dual Industrial, Scientific, and Medical-band (2.4 and 5.8 GHz bands) is demonstrated. This antenna combines omni-directional and broad bandwidth in an easy to fabricate structure. Experimental results indicate that the VSWR 2:1 bandwidths achieved were 8.2% and 18.2% at 2.45 GHz and 5.5 GHz. Effects of varying the serial-slot dimensions and the ground-plane size on the antenna performance are also described.     

A compact Q-K-band dual frequency feed horn

A millimeter-wave dual frequency circularly polarized feed for an offset reflector antenna is being developed for a portable satellite ground terminal. The two frequency bands areQ- andK-bands for transmit and receive, respectively. A compact feed design consisting of a single corrugated horn with two circular waveguide concentric openings at the horn throat is described. Good aperture efficiency and low sidelobes in both of the frequency bands are achieved.     

Resonant type leaky-wave antenna using image NRD guide

A novel leaky-wave antenna constructed from an image non-radiating dielectric waveguide (INRDG) is presented. Unlike conventional leaky-wave antennas, the broadside radiation is realised by utilising the resonant characteristic of the leaky INRDG waveguide mode. Experimental results measured at Ku band confirm the effective performance of the antenna.     

Leaky wave antenna based on image NRD guide with staircase-shapeddielectric slab

A leaky wave antenna based on the use of an asymmetric image nonradiative dielectric (NRD) guide has been studied experimentally. By using a staircase-shaped image NRD guide, the gain bandwidth of the antenna becomes three times that of a leaky wave antenna using an ordinary image NRD guide. Moreover, this antenna employs a flared horn in the NRD guide which makes the H-plane beamwidth controllable     

Slot-loaded, meandered rectangular microstrip antenna with compactdual frequency operation

A novel single-feed compact dual-frequency design is demonstrated. The proposed design consists of a rectangular patch loaded with two parallel slots close to the radiating edges and meandered with slits at the non-radiating edges. The two operating frequencies have parallel polarisation planes and, by varying the insetting slit length, the frequency ratio of the two frequencies is tunable in the range of ~1.8-2.4. In addition, with the insetting slit, the two frequencies can be greatly lowered, which results in a large antenna size reduction for fixed dual-frequency operation     

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.     

A C/ka dual frequency dual Layer circularly polarized reflectarray antenna with microstrip ring elements

This paper reports a dual frequency dual layer circularly polarized reflectarray operating in the C and Ka bands. A 0.5-m right-hand circularly polarized planar reflectarray antenna is designed using microstrip ring elements of variable rotations to achieve a cophasal beam at broadside. The microstrip ring elements are more compact than the traditional reflectarray elements and can minimize blockage for the multilayer multifrequency applications. The highest efficiencies measured are 46% at 7.3 GHz and 38% at 31.75 GHz. The tested cross-polarization levels are -21 dB at 7.3 GHz and -29.2 dB at 31.75 GHz at the broadside direction. The tested results show that the designed ring element is suitable for both the single and dual layer applications with good bandwidth and circularly polarized performance.     

Phase-locked loop with dual phase frequency detectors for high-frequency operation and fast acquisition

The sequential phase frequency detector (PFD) has an unlimited error detection range and the precharge PFD has one and a half times better resolution performance than the sequential PFD. Therefore, by selective operation of the appropriate PFD connected to the well-adjusted charge pump, an unlimited error detection range, a high-frequency operation, and a higher speed lock-up time can be achieved. In this paper, we propose a phase-locked loop (PLL) with dual PFDs in which advantages of both PFDs can be combined. This structure can improve the tradeoff between acquisition behavior and locked behavior.     

Low cost microstrip-fed dual frequency printed dipole antenna forwireless communications

A low cost microstrip-fed dual frequency dipole antenna has been developed for personal communication network (PCN) and wireless LAN (WLAN) applications in the 2.4 and 5.2 GHz bands. The antenna radiates bi-directionally and has a double-sided structure to enable transition from a balanced planar stripline to unbalanced microstrip line. The 10 dB bandwidths achieved were 18.75 and 7.7% at 2.4 and 5.2 GHz, respectively     

基于超材料馈电网络的全向双极化天线阵设计

为了减小对天线阵辐射特性的影响,提出并设计了一种平行平板传输线结构的超材料串联馈电网络,基于超材料传输线设计了零相移传输线,利用零相移传输线设计了串联馈电网络。基于该馈电网络设计了一种全向水平/垂直双极化4元天线阵。天线阵由4个全向双极化天线单元和2个超材料串联馈电网络组成。全向双极化天线单元由折顶偶极子天线和缝隙电容加载的零相移圆环天线构成。利用HFSS仿真软件对该天馈系统进行了仿真,结果表明,该天线阵的中心工作频率为3.5 GHz,最大增益为7 dB,交叉极化电平小于-35 dB,隔离度大于40 dB,不圆度小于±1.2 dB,满足5G通信对基站天线和多入多出天线的要求。     

Suppression of parasitic currents on feed lines of colinear dual antenna systems

Investigations are reported of an antenna system consisting of a pair of colinear dipoles with a feed line "isolator section" which provides independent operation of the dipoles over an octave frequency range. The isolator section acts as a band elimination filter for the parasitic currents induced on the outer surface of the transmission line of the upper dipole. Suppression of these currents eliminates distortion of the antenna radiation patterns and significantly reduces coupling between the dipoles. Over the 200-400-MHz range, an interdipole isolation greater than 35 dB has been achieved between the colinear dipoles separated by 1.5 m.