Optimization of novel high-power millimeter-wave TM01-TE11 mode converters

In this paper, a numerical study of direct TM₀₁-TE₁₁ mode converters in highly overmoded, bent smooth, circular waveguides is presented for high-power millimeter waves. The various shapes of bent waveguides are elaborately chosen, and their optimized geometrical dimensions have been achieved with a general optimization code employing the coupled mode theory. The mode converters designed can have high conversion efficiencies over 98% and wide bandwidths of 28%     

Input impedance of a coaxial line probe feeding a circularwaveguide in the TM01 mode

By means of the conversion of complex power technique (CCPT), a formally exact full-wave solution is given for the case of a coaxial line probe fending a circular waveguide for TM₀₁ modal excitation. The overall scattering matrix of the coaxial-line-prove-circular-waveguide system is deduced. Numerical results for the impedance as `seen' by the coaxial line are presented and compared with experimental results obtained in the 9.0-11.5-GHz frequency range. Their agreement is reasonably good except at the lower frequencies (<10.0 GHz), where the TM₀₁ mode in the circular guide is close to its cutoff frequency (8.14 GHz)     

Wideband dual-polarised microstrip patch antenna

A dual-polarised microstrip antenna capable of achieving a wide bandwidth, a high isolation, low cross-polarisation levels and low backward radiation levels is presented. The H-shaped coupling aperture is used. For wide bandwidth and easy integration with active circuits, it uses the aperture-coupled stacked microstrip square patches. Measured return loss exhibits a bandwidth of over 20.9%, and isolation is better than 36 dB over the bandwidth. Cross-polarisation levels and the front-to-back ratio are better than 22 and 21 dB, respectively     

A single-period TE02-TE01 mode converter in ahighly overmoded circular waveguide

A single-period 60 GHz TE₀₂-TE₀₁ mode converter for use in an electron cyclotron heating (ECH) system for magnetically confined plasmas is presented. The mode converter is very compact and has a broad bandwidth and a theoretical conversion efficiency of 97.6%. A method of computing the reflection from converters is presented and used to show that reflection from the single-period mode converter is minimal. Experimental results are consistent with theoretical calculations     

Achievement of pencil-beam radiation from a TM01 modecircular waveguide source

A method employing appropriately placed parallel-metallic plates in the aperture of a TM₀₁ mode circular waveguide source so as to have it produce pencil-beam radiation is described and analyzed. Programmed computations, with experimental verification, are given for the case of a C-Band TM₀₁ source flared out to a conical horn so as to produce moderate (22 dBi) gain. Means of extending the method to achieve higher gains (40 dBi to 60 dBi) and to modify the plate arrangement so as to produce the same effect with a TE₀₁ mode are briefly outlined     

Wideband single-fed circularly polarised patch antenna

A novel circularly polarised (CP), single-fed microstrip antenna is presented. The antenna consists of a stacked structure of almost square patches. The proposed design has a reduced antenna size compared to the conventional CP microstrip antenna at a given operating frequency. The impedance and axial ratio bandwidths are large and CP radiation quality is excellent over the entire upper hemisphere. The proposed antenna is suitable for global positioning system (GPS) applications.     

Wideband patch antenna with low cross-polarisation

A wideband patch antenna with low cross-polarisation is presented. Based on a novel meandering-shaped probe feed, an impedance bandwidth (SWR<2) of 24% has been obtained. The cross-polarisation is less than -20 dB across the operating bandwidth. The antenna has a gain of 9dBi.     

Wideband V-slotted diamond-shaped microstrip patch antenna

A new wideband microstrip antenna with V-slotted diamond-shaped patch on a single-layer foam dielectric and probe feed is presented. The broadband design is achieved by the excitation of resonance frequencies of the diamond patch and V-slot. An impedance bandwidth as high as 50% is achieved, where the antenna gain is stable and its variation is within 1 dB.     

一种新型2.4GHz频段加载贴片天线的设计

采用在贴片上开槽和加载的方法,设计了一种用于2.4GHz频段无线通信设备、内缩渐变线馈电的新型结构贴片天线.给出仿真设计的性能和多个天线样品的实测输入驻波比曲线和远区辐射特性图,详细研究分析了不同加载条件、不同辐射边尺寸对输入驻波比的影响.实测结果表明,该天线在2.4GHz频段上获得超过15%的相对带宽(VSWR<2),而且尺寸比相应频段的微带贴片天线更加微型化.     

Thick circular iris in a TE11 mode circular waveguide

The TE₁₁-mode excitation of a concentric circular iris of finite thickness in a circular waveguide is analyzed by Galerkin's method with even and odd excitation. Agreement between calculated and measured dominant mode scattering parameters is generally within experimental accuracy     

Wideband probe-fed circularly polarised circular loop antenna

A wideband probe-fed circularly polarised circular loop antenna is presented. The wideband performance is achieved by introducing a parasitic loop inside the original loop that is driven by a feed probe. It is found that the 2 dB axial ratio bandwidth can be increased from 6% for a single circular loop to 16% by the introduction of a parasitic loop.     

Wideband folded shorted patch antenna with double L-slots

A novel folded shorted patch antenna for broadband operation is presented. It has an impedance bandwidth (SWR < 2) of 99.4%, which is more than three times that of the antenna without slots. Also, it is 0.0852lambda_L in height and 0.142lambda_L in length, where lambda_L is the free space wavelength at the lower cutoff frequency of its operating bandwidth. Therefore, it is very suitable for today's multiband indoor wireless communication systems.     

Wideband and small size star-shaped microstrip patch antenna

A new wideband and small size star-shaped patch antenna, fed by a small rectangular patch, is proposed. Simulation via a finite element program and measured results of return loss, and the E- and H-plane radiation patterns of the proposed antenna, are presented. The antenna is able to achieve in the range 5-9.3 GHz an impedance bandwidth of 63% for return loss of less than -10 dB     

Wideband folded shorted patch antenna with low profile

The design and measurement of a low-profile folded patch antenna with a short-circuited element are presented. By introducing dual-resonance, a significantly improved bandwidth of almost 30% for S ₁₁<-10 dB, which ranges from 1.48 to 1.99 GHz, is achieved, while the total profile of the proposed antenna is kept at a very low level of 0.046 lambda₀ only. The impedance matching, radiation patterns and gain curve are measured and illustrated. This antenna is easy to fabricate and its performance is less susceptible to manufacturing errors. Owing to its wideband and low-profile characteristics, it is highly suitable for applications in mobile communication systems, such as PCS, DECT and PHS     

Wideband stacked patch antenna fed by meandering probe

A meandering probe fed stacked patch antenna is presented. The stacked patch configuration can greatly enhance the impedance bandwidth. Bandwidth of up to 37% (SWR<1.5) has been achieved. The cross-polarisation is less than -20 dB across the operating bandwidth. The proposed antenna has symmetric co-polar radiation patterns in both E- and H-plane. The antenna has a gain of 9 dBi.     

Wideband aperture coupled stacked patch antenna using thicksubstrates

An aperture coupled stacked patch microstrip antenna is presented which is capable of operating over a bandwidth in excess of 50%. Measured and predicted impedance behaviour and gain over the band are given. Other important factors such as surface wave efficiency and back radiation levels are presented     

Wideband stacked SSFIP patch antenna for SAR applications

A dual-polarised aperture-coupled microstrip stacked patch antenna with stacked feed lines is presented. The antenna is capable of operating over a bandwidth of 30% with improved front-to-back ratio performance. The patches are excited through non-resonating crossed slots. The feed lines are separated by a thin substrate to enhance the port decoupling. The measured impedance and radiation pattern of the antenna at C-band are presented.     

Wideband L-probe-feed patch antenna with dual-band operation forGSM/PCS base stations

A dual-band microstrip composed of two patches and two L-probes is proposed. The antenna displays wide-bandwidth characteristics and can be implemented as a dual-mode GSM/PCS base station antenna     

Single feed wideband circular polarised patch antenna

Based on the air gap and stacked patch configuration, a new wideband circular polarised patch antenna is proposed. Significantly increased impedance and axial ratio bandwidths can be achieved without increasing implementation complexity compared with that of existing patch antennas.     

A circular patch antenna for radio LAN's

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