Dual-frequency electric-magnetic-electric microstrip leaky-mode antenna of a single fan beam

This paper presents a dual-frequency electric-magnetic-electric (EME) microstrip exhibiting two leaky-wave regions of similar radiation characteristics like the microstrip EH/sub 1/ mode. The EME microstrip incorporates a photonic bandgap (PBG) structure, which is a two-dimensional array consisting of unit cell made of coupled coils connected by a via. The PBG structure employed in the EME prototype conducts at dc and shows the first stopband between 8.8-12.4 GHz, thus rendering the so-called magnetic surface. The EME microstrip is essentially made by substituting the PBG cells for the metal strip of a conventional microstrip. The finite-element method (FEM) analyses of the PBG structure show that the first and second modes are TM-like and TEM-like, respectively. The latter is leaky between 12.4-12.9 GHz and is found to be responsible for the second leaky region of the EME microstrip. The dispersion characteristics of the EME microstrip are obtained by two theoretical methods, namely, the matrix-pencil method and the FEM. Both show excellent agreement in the two leaky regions. Furthermore, the measured far-field radiation patterns of the two leaky regions also validate the dispersion curves. The first leaky region is of EH/sub 1/ type and between 5.05-5.45 GHz. The second leaky region radiates a frequency-scanning fan beam between 11.95-13.0 GHz, similar to those of the EH/sub 1/ mode. Detailed modal current analyses show even and odd symmetry along longitudinal and transverse plane of EME microstrip, respectively, further confirming the two leaky regions behave like the well-known EH/sub 1/ leaky mode. The proposed EME microstrip enriches the modal characteristics of the conventional, uniform microstrip and is thus a manifestation of application of PBG structure for new guiding device.     

Microstrip-fed crossed-slot array antenna

A microstrip-fed crossed-slot array antenna having a circular polarisation is developed. First, a single crossed-slot antenna, that can radiate a circularly polarised wave in the broadside direction, is designed and its coupling level to the microstrip line is analysed. Based on this result, an eight-element crossed-slot array is designed and its characteristics are experimentally investigated at 12 GHz band. The return loss of -17 dB is obtained at the design frequency of 11.85 GHz, and the axial ratio of less than 3 dB is achieved over the fractional bandwidth of 5%.     

Microstrip leaky-mode antenna array

The first-pass design of a linear eight-element microstrip leaky-mode antenna array is proposed, built, and tested, showing a gain of 18.5 dB, directivity of 23.5 dB, and pencil beam with 3-dB beamwidth (Az/El) of 10.2°/14.3°. Excellent agreement between the theoretical prediction and measured results for the array antenna performance is obtained     

A dual-beam micro-CPW leaky-mode antenna

A quasi-planar leaky-mode antenna employing the second higher order leaky mode of even symmetry in its leaky-wave regime has been proposed for a new antenna configuration consisting of a microstrip and a coplanar waveguide (CPW) on both sides of the substrate. The new antenna, also known as the micro-CPW antenna, is directly fed by a CPW line without matching circuit. One particular K-band antenna of 36 mm long [about 2.7 free-space wavelengths (λ₀) at 22.1 GHz] shows 5.3% impedance bandwidth for VSWRs less than 2.0 for frequencies between 21.927-23.110 GHz, 11.0-dB antenna gain, and 90.02% efficiency. Detailed analyses show that the dual-beam antenna is linearly polarized along two slanted lines, which lie in the longer axes of the ellipses that approximate the radiation contours. Both theoretical and experimental data for the micro-CPW antenna agree very well for the particular design. The proposed micro-CPW antenna is suitable for active integrated antenna integration at higher microwave and millimeter-wave frequencies     

High-frequency leaky-mode excitation on a microstrip line

The excitation of leaky modes (LMs) and the continuous spectrum (CS) on a microstrip line at high frequencies from a delta-gap source is studied. The delta-gap source models a practical source or discontinuity on the line. It is shown that the current excited from the source exhibits spurious effects at high frequencies due to the excitation of the CS (radiation spectrum), which may or may not be dominated by a physical LM, depending on the frequency range and the substrate permittivity. In some cases, the spurious effects are due to a physical LM, while in other cases the effects are due to the excitation of one or more "residual-wave" (RW) currents, which have not been previously studied for open microstrip lines. There are two types of RW currents: a free-space type and a surface-wave type. Depending on the frequency and the structural parameters, either of these may be the more dominant. At certain frequencies, weakly attenuated high-order LMs may also be excited, in which case spurious effects are observed out to large distances from the source     

Microstrip-fed quasi-Yagi antenna with broadband characteristics

A compact and uniplanar antenna with broadband characteristics is presented. The novel Yagi-like printed dipole array antenna is fed by a microstrip-to-coplanar strip transition, and uses the truncated microstrip ground plane as its reflecting element. An X-band prototype measures a bandwidth of 17%. With 6.5 dB gain, 18 dB front-to-back ratio, and lower than -15 dB cross-polarisation level at 10 GHz     

一种微带馈电铲形终端椭圆缝隙超宽带天线

设计了一种具有铲形终端微带馈电椭圆缝隙及枝节调节和接地板阶梯凹槽的超宽带(UWB)天线。利用仿真软件HFSS分析了铲形半椭圆、椭圆缝隙及枝节、半圆切槽、接地板与辐射体间隙、接地板三角形切角和阶梯凹槽等结构对天线性能的影响,对天线结构参数进行了优化。实测天线的阻抗带宽为2.8~12.0 GHz,在3.1~10.6GHz范围内基本呈全向性,并且具有较稳定的增益,约为2.5~4.6 d Bi。该天线可广泛用于无线通信领域。     

Reconfigurable leaky-mode/multifunction patch antenna structure

A reconfigurable aperture where different types of antennas and arrays with multiband coverage and multiple functions share a common planar physical aperture is proposed. Using either conventional or MEMS switches, a microstrip-based leaky-mode antenna array can easily be reconfigured to patch antennas operating at multiple frequency bands as well as monopulse radars for both azimuth and elevation tracking. The feasibility of the concept has been demonstrated by prototype design and measurement of a single-channel X-band leaky-wave/S- and C-band patch antenna structure     

Higher order mode excitation for high gain microstrip patch antenna

Higher order mode excitation in the microstrip patch has been achieved to alleviate the low gain problem associated with this particular class of antennas. This higher order mode excitation is achieved by geometric modification of the radiating patch. The designed antenna structure is simple in nature, provides easy fabrication and manufacturing while exhibiting high gain characteristic. The proposed antenna has a measured gain of 10.21 dBi at the operating frequency of 16 GHz. The half power beam width is approximately 36° and 34° in the H- and E- planes respectively. The antenna can be used in the different applications related to the Ku band.     

准八木型宽带高增益微带天线

基于八木天线的结构设计并制作了一个准八木型宽带高增益微带天线,利用三维电磁仿真软件(Ansoft HFSS)进行仿真设计,在已有的单一引向器结构的基础上,通过增加引向器数量实现了高增益和较宽的带宽。实际测试表明:天线工作频段在4.8~6.4 GHz,在中心频率5.6 GHz处,峰值增益约为10.2 dB,前后比约为21dB,与仿真结果基本吻合。另外,还给出了准八木型高增益微带天线的设计过程,并对具体结构和参数的选择对天线性能的影响进行了比较和讨论。     

Self-adjusting microstrip antenna

A microstrip circuit operating in the G band is presented. It allows all emitting printed antenna to self-tune its resonance frequency when it is disturbed, in order to stay resonant and matched at the desired transmit frequency. The principle, design and experimental results of the circuit are presented     

Microstrip-fed printed lotus antenna for wideband wireless communication systems

A novel printed antenna, fed by a microstrip line, has been designed for wideband wireless communication systems. The new antenna shows a wide -10dB bandwidth of over 60%. In addition to being small in size, the antenna exhibits stable far-field radiation characteristics in the entire operating band with relatively high gain, low cross polarization, wide beamwidth, and good front-to-back ratio.     

New compact microstrip antenna

A new microstrip antenna geometry with considerable reduction in size, with similar radiation characteristics to those of an equivalent rectangular patch antenna is proposed. A relationship has been suggested for finding out the resonant frequency of the new geometry, and its validity has been established by the experimental results. Without increasing the aperture area, this geometry also offers a facility for considerably reducing the resonant frequency compared to conventional patches     

Circularly-polarised disk-sector microstrip antenna

A novel disk-sector microstrip antenna with specific flare angles for circular polarisation (CP) operation is proposed and experimentally studied. Results show that by selecting the flare angle of the disk-sector microstrip patch to be 65 or 70°, right hand or left-hand CP radiation can easily be obtained using a single probe feed. Details of the design considerations are described, and measured CP characteristics are presented     

Broadband conical microstrip antenna

Conical patch antennas, excited on TE11-mode are studied and their resonance frequencies are computed. These antennas present a broader bandwidth compared to classical microstrip antennas and, furthermore, good impedance matching can be easily obtained.     

Dual frequency microstrip antenna

A single-feed dual-frequency microstrip antenna is reported. It can be impedance-matched independently at the two frequencies of operation. The tested antenna has a VSWR of 1.33 at 2.32 GHz and 1.12 at 9.425 GHz. The configuration reported here can be impedance matched over a wider frequency range using standard impedance-matching techniques.     

Dual-polarised wideband microstrip antenna

A dual-polarised aperture-coupled microstrip antenna with a wide bandwidth, a high isolation, low cross-polarisation levels and low backward radiation levels is presented. The square patch is fed at two corners via H-shaped apertures. The measured return loss exhibits a bandwidth of over 24.4% and the isolation is better than 30 dB over the bandwidth. The cross-polarisation levels and the front-to-back ratio are better than -23 and 22 dB, respectively     

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.     

Compact two-port microstrip antenna

A compact two-port array antenna which operates in the X-band is described. This antenna, which combines a high gain with a relatively wide bandwidth, was conceived using mutual coupling and parasitic coupling techniques. The analysis and the simulations performed using the transmission line method and matrix algebra are briefly presented     

Planar dual-band microstrip antenna

A novel dual-band microstrip antenna is introduced. The entire structure is planar and can be easily mass-produced by using printed-circuit technology. The antenna consists of multiple layers with metallic strips placed at one of the dielectric interfaces under the radiating patch. The resonant frequencies can be selected over a wide frequency range, and the impedance matching at those two frequencies is relatively simple. The physically intuitive cavity model is used for the analysis. A relatively simple design scheme is included