Theory and experiment of dual-mode microstrip triangular patch resonators and filters

In this paper, we report on the results of an investigation into dual-mode operation of microstrip triangular patch resonators and their applications for designing dual-mode bandpass filters. It has been found theoretically that the dual modes can result from the rotation and superposition of a fundamental mode. The characteristics of the dual modes and their mode splitting are described. The applications of this new type of dual-mode microstrip patch resonator in the design of microwave planar filter are presented. A circuit model for operation of this type of filter is proposed. Two- and four-pole filters of this type are demonstrated for the first time. Both theoretical and experimental results are presented.     

Analysis of a suspended patch antenna excited by an electromagnetically coupled inverted microstrip feed

A suspended patch antenna electromagnetically excited by an inverted microstrip line has been studied based on a full-wave transmission line analysis in conjunction with a microwave network theory. The input impedance calculated has been compared with measured data.     

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     

Circular-waveguide-fed microstrip patch antennas

A microstrip patch antenna fed by a circular waveguide is presented. The microstrip patch built on a foam substrate is laid on the flange of the circular waveguide's open mouth. The waveguide feeds the patch by coupling energy to the patch through a narrow slot underneath the patch. Two operating frequency bands were observed and the characteristics of the antenna were measured.     

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.     

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     

Scattering from a microstrip patch

A solution to the problem of plane wave scattering by a rectangular microstrip patch on a grounded dielectric substrate is presented. The model does not include the microstrip feed, and thus does not include the so-called "antenna mode" component of the scattering. The solution begins by formulating an electric field integral equation for the surface current density on the microstrip patch. The integral equation is solved using the method of moments. Computed data for the patch radar cross section (RCS) is found to be in close agreement with measurements over a broad frequency range. The microstrip RCS versus frequency consists of a number of large peaks which are identified as impedance or pattern factor resonance peaks.     

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.     

A shaped-beam microstrip patch reflectarray

This paper describes a microstrip reflectarray antenna designed to produce a shaped-beam coverage pattern using phase synthesis. The concept is demonstrated with a Ku-band linearly polarized reflectarray designed to provide coverage of the European continent and measured results are compared to those obtained for a previously designed shaped-reflector antenna designed for the same coverage specifications. Results validate the shaped-beam reflectarray concept, although there are disadvantages to the reflectarray such as narrow bandwidth and reduced aperture efficiency that may offset the mechanical and cost advantages of the flat surface of the reflectarray     

微带整流天线的设计与试验

微带贴片整流天线质量轻,接收面积大,非常适合微波飞机、高空平台等微波输电中对天线质量要求严格的场合.提出了两种微带整流天线的设计,结合高频仿真软件ADS 2003C、IE3D V10.0对天线的设计实现方案进行了研究,给出了一整套的微带贴片整流天线的设计步骤,通过试验对各种实现方案进行了比较和对设计步骤的正确性进行了验证.     

Cylindrical-rectangular microstrip patch antenna for circularpolarization

The circular polarization condition for a rectangular microstrip patch antenna on a thin cylindrical substrate is investigated. The theoretical study is based on the modal-expansion theory, which is valid for the thin-substrate case. Numerical results for the aspect ratio of the cylindrical-rectangular patch, the optimal feed point for minimum voltage standing wave ratio and the 3-dB bandwidth for circularly polarized radiation are analyzed. Effects of the curvature on the circular polarization condition are also discussed     

一种新型V型槽圆极化微带贴片天线

提出了一种基于非对称V型槽加载的探针馈电圆极化单层钻石形微带贴片天线。通过调节V型槽的槽宽、槽长、开槽倾角及馈电点位置可实现微带贴片天线的圆极化辐射。研究了V型槽尺寸对微带贴片天线性能的影响。结果表明:介质厚度为0.051λ_0(λ_0为中心工作波长)时,天线的阻抗带宽大于9%(VSWR≤2),圆极化带宽为3%(AR≤3),最大增益可达6.29 d Bi,最小轴比小于0.5 d B。     

Polarisation agile active microstrip patch arrays

Two three-element polarisation-agile active microstrip patch arrays have been developed. The radiating elements are square patches each with two transistors mounted on adjacent edges. The patches radiate orthogonal modes, the relative phase of which can be varied. Radiation patterns show good agreement with predictions from theory, in both linear and circular polarisation, and no grating lobes were observed     

Mutual coupling between microstrip patch antennas

A theoretical approach to the mutual coupling phenomenon between microstrip patch antennas of arbitrary geometry and alignment is presented. The theory employs an equivalent magnetic wall model for each single radiator, a series expansion in resonant modes in connection with a reaction concept treatment of antenna interaction. Good agreement of theoretical and experimental data is observed in a wide frequency range for various element spacings.     

Cross polarization of microstrip patch antennas

The cross-polarization level of circular and rectangular patches is evaluated by finding the peak value angles. The peak value is strongly dependent on substrate dielectric constant, varying roughly as1/epsilon. Aspect ratio of a rectangular patch has little effect on peak values or location. Patch thickness also has little effect; results are limited to thin patches as surface waves are not included.     

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     

Active millimetre-wave aperture-coupled microstrip patch antennaarray

An active millimetre-wave aperture-coupled microstrip patch and four element array are presented. The design methodology is discussed and experimental measurements between 41 and 42 GHz are presented. The results presented should have useful applications in phased arrays and communication systems at EHF 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     

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.