Low-cost monopulse antenna using bi-directionally-fed microstrip patch array

A new technique for realising a simple low-cost monopulse antenna using a symmetrical bi-directionally-fed microstrip patch array is described. The antenna is designed and demonstrated at Ka-band. Two squinted beams are radiated from a bi-directionally fed microstrip patch array, and a sum/difference pattern is synthesised using the in-phase and out-of-phase signals achieved using a hybrid ring coupler. The measured return loss is better than 10 dB at the sum and difference port, and the depth at broadside is more than 30 dB.     

Dual polarization stacked microstrip patch antenna array with verylow cross-polarization

This paper describes the development and performance of a wideband dual linear polarization microstrip antenna array used in the Danish high-resolution airborne multifrequency polarimetric synthetic aperture radar, EMISAR. The antenna was designed for an operating frequency of 1.25 GHz±50 MHz and was built as an array of 8×2 probe-fed stacked microstrip patches. The feeding network is constructed in microstrip and is capable of handling 6 kW of peak input-power at an altitude of 45000 ft (unpressurized). The impedance bandwidth (return loss better than -14 dB) of the antenna is 10%, the isolation between the horizontal and the vertical ports of the array is 50 dB and the cross-polarization suppression is 40 dB. A new design principle for simultaneously achieving very low cross-polarization and low side lobes in dual linear polarization antenna arrays has been applied     

一种S波段宽带微带贴片天线阵列的设计

介绍了一种宽带微带贴片天线单元及2元阵列的设计方法,天线工作的中心频率为rl_5OHz（S波段）。天线单元设计中采用口径耦合理论和层叠贴片天线结构,有效增大了天线的阻抗带宽。仿真结果表明该天线阵列实际增益达到11．9dB;在2．27～2．78GHz频率范围内端口驻波比小于2,相对带宽为20．4％;交叉极化电平为-31dB,证明该天线阵具有宽频带、低交叉极化等优良性能。     

Center-fed microstrip patch antenna

A novel feeding scheme for microstrip patch antennas is presented, which consists of a coaxial probe and shorting pin separated by a narrow slot centrally cut at the radiating patch. The impedance and radiation characteristics of a conventional probe-fed microstrip patch antenna and the proposed microstrip patch antenna are experimentally examined and compared. The effects of the slot length on the antenna operation are also discussed.     

Small microstrip patch antenna

A novel small microstrip patch antenna is presented. The probe-fed circular microstrip patch incorporates a single shorting post which significantly reduces the overall size of the antenna. Experimental and theoretical impedance behaviour and radiation characteristics of the modified patch are given. Very good agreement between experiment and theory was achieved     

Broadband microstrip patch antenna

The characteristics of a rectangular microstrip antenna with an L-shaped probe are investigated. A foam layer with a thickness of around 10% of the wavelength is used as the supporting substrate. An impedance bandwidth of 35% and an average gain of 7.5 dBi can be achieved. The radiation pattern is stable across the passband     

A wideband linear U-slot microstrip patch antenna array for wireless application

Microstrip antennas suffer an inherent disadvantage of narrow impedance bandwidth, normally within 5%. In this article, a single layer linear U-slot microstrip patch antenna array is designed, fabricated and characterised. The measured results agree well with the simulated, showing an enhanced impedance bandwidth (voltage standing wave ratio < 2) of 10.6%, ranging from 5.35 to 5.95 GHz, on an FR4 substrate. The antenna array has high efficiency and gain. Only a pair of sidelobes appear in the E plane radiation pattern. The reported linear array design can provide a method of expanding to 4 × N antenna array for satellite to ground communication operating at C band.     

A 24-GHz high-gain Yagi-Uda antenna array

A compact 24-GHz Yagi-Uda antenna has been developed using standard design tables and simple scaling to take into account the added capacitance due to the supporting dielectric substrate. The antenna results in a directivity of 9.3 dB, a front-to-back ratio of 11 dB, and a bandwidth of 2.5-3%. The Yagi-Uda antenna has been implemented in an 11-beam system using a planar array and a 2-inch Teflon spherical lens. The measured patterns show a 22 dB gain beam, a cross-polarization level of -24 dB, and a crossover level of -6 dB. The design method presented in this paper is quite straightforward, and can be used to develop low-, medium-, and even high-gain endfire Yagi-Uda antennas.     

Stacked H-shaped microstrip patch antenna

A small H-shaped microstrip patch antenna (MPA) with enhanced bandwidth is presented. The H-shaped antenna is first studied by a transmission line model and then is fully analyzed with a MoM code. A stacked patch configuration is proposed to increase the narrow bandwidth, radiation efficiency and directivity. The stacked H-shaped MPA is studied using Chu's fundamental limit for electrically small antennas.     

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     

一种天线馈源用宽带孔径耦合层叠微带贴片阵的设计

介绍了一种宽带孔径耦合层叠微带辐射单元的工作原理,着重分析了该辐射单元主要结构尺寸对其阻抗带宽的影响。该辐射单元阻抗带宽（VSWR≤2：1）在S波段达到了30％以上。作为某抛物反射面天线的馈源,由4个该辐射单元组成四单元微带贴片天线阵后,其性能满足天线系统要求。     

A retrodirective microstrip antenna array

A Van Atta retrodirective reflector was designed and developed, using an aperture-coupled microstrip antenna array. This reflector possesses the advantage of reflecting high fields to the source point over a wide range of incidence angles and, owing to the low cost and conformability of the structure, is suitable for applications in intelligent vehicle highway systems (IVHS). An approximate theory associated with the reradiation and scattering principles of the reflector is presented for the purpose of understanding and designing the reflector. The utility of the retrodirective reflector was demonstrated by comparison with a plate reflector and a microstrip antenna array without a feed structure. Finally, a reflector with switches in the middle of the microstrip feed lines was investigated for possible applications in communications and remote identification     

Double-layer high-gain microstrip array antenna

Novel double-layer microstrip array antennas are introduced for high-gain applications. In the proposed antennas, the complex and lossy feed network is not needed. Rather the double structure provides the field distribution at the aperture for the beam-focusing effect. A relatively simple design method based on a cavity model is presented     

Microstrip patch array antenna

A microstrip array with mutual coupled rectangular patch radiators is described. By the avoidance of a corporate feeding network, advantages in the antenna performance and design are realisable. Experimental results are presented for both linearly and circularly polarised antennas which demonstrate the usefulness of this special antenna configuration.     

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.     

Broadband semicircle-fed flower-shaped microstrip patch antenna

A new wideband flower-shaped microstrip antenna patch, semicircle-fed, is investigated. The broadband characteristic is achieved by introducing flower petals at the four sides of a rectangular patch. The proposed antenna is able to achieve an impedance bandwidth of 63% for VSWR less than 2. Using the same excitation mechanism, a comparison between the proposed antenna, a similar-size rectangular-shaped patch antenna and a diamond-shaped patch antenna is given.     

Liquid crystal tunable microstrip patch antenna

A microstrip patch antenna operating in the 5 GHz range and tuned by liquid crystal (LC) is described. The simulated tuning range is 8% while the measurements showed a range of 4%. Losses in the commercially available LC material at these frequencies give rise to antenna efficiencies ranging from 35?40% at best and falling to around 20% when the LC is in the unbiased state.     

Simple tunable dual-band microstrip patch antenna

A novel technique for designing a tunable dual-band microstrip patch antenna is proposed. Dual-band operation is easily achieved by loading a microstrip patch antenna with one varactor diode placed on a small gap between a square patch and a parasitic strip. It is observed from the measured result that the proposed antenna shows a wide tuning range at the two resonant frequencies.     

Dual band tunable microstrip patch antenna

A simple design for a dual-band microstrip antenna operating at 3 GHz is presented. The dual band operation is obtained when the antenna is loaded with a cross-line shorted with a ground plane at one end. The frequency separation is found to be sensitive to the position of the cross-line     

Compact dual-band dual-polarisation microstrip patch antenna

A novel compact, conformal, dual-band, dual-polarisation antenna is presented. This antenna is capable of generating two distinct frequencies with different polarisation and radiation pattern characteristics: a monopolar mode for terrestrial cellular communication and a circularly polarised, upward oriented pattern for satellite mobile communication. Bandwidths of 2 and 4%, respectively, have been obtained in the two modes