Slot-coupled microstrip antenna for broadband circular polarisation

A microstrip antenna with broadband circular polarisation (CP) is presented. The proposed microstrip antenna has a circular patch and is excited by a series microstrip-line-feed configuration through the coupling of a ring slot in the ground plane. The broadband operation is achieved by coupling two CP resonant elements, which are due to the circular patch and the ring slot, respectively. A typical prototype using foam material of thickness 5 mm as the antenna substrate is constructed. Measured results show the 3 dB-axial-ratio bandwidth centred at 2500 MHz is more than 10%.     

Millimeter-wave proximity-coupled microstrip antenna on an extendedhemispherical dielectric lens

A low-cost, high-gain, millimeter-wave antenna is presented. The antenna is composed of a proximity-coupled microstrip patch mounted on the back surface of a substrate lens. The antenna utilizes low dielectric constant, low-cost materials and is therefore suitable to many commercial millimeter-wave systems. A full-wave analysis was developed to analyze the performance of the printed antenna and a prototype was developed for operation at 38 GHz. The impedance bandwidth of the prototype was 8% and the gain was approximately 30 dBi across this frequency span with a front-to-back ratio greater than 60 dB     

Wideband circular patch antenna operated at TM01 mode

The characteristics of a circular patch microstrip antenna with a top-loaded monopole feed are investigated. Air is used as the dielectric substrate. The distance between the radiating patch and ground plane is ~0.15λ₀. The patch is excited in the TM₀₁ mode. An impedance bandwidth (SWR<2) of 50% and an average gain of 5dBi are obtained     

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     

Planar elliptical antenna for ultra-wideband communications

A printed planar elliptic patch, juxtaposed with the ground pattern in a single substrate, providing an ultra-wideband impedance bandwidth, is presented. The ultra-wideband property for the proposed antenna is achieved by using a new impedance-matching technique of cutting a notch in the ground pattern opposite the microstrip line. The concavity of the ground pattern serves as an effective means of adjusting the gap between the radiating element and the ground plane. With suitable size of notch chosen, the impedance bandwidth of the proposed antenna can be enhanced. Details of the proposed antenna design and measured results are presented and discussed.     

Microstrip antenna aperture-coupled to a microstripline

A new technique for feeding printed antennas is described. A microstrip antenna on one substrate is coupled to a microstripline feed on another parallel substrate through an aperture in the ground plane which separates the two substrates. A simple theory explaining the coupling mechanism is presented, as well as measurements of a prototype aperture-fed antenna.     

Design of a compact broadband microstrip patch antenna with probe feeding for wireless applications

In this paper the design and development of a compact broadband probe-fed Microstrip patch antenna for bandwidth improvement and antenna size reduction in a single design is proposed. The well-known technique of effective substrate thickness increment is performed to improve the impedance bandwidth, whereas for size reduction the electrical length of the conducting patch has been increased. A compact probe-fed inverted U-shaped microstrip patch antenna with a W-shaped ground plane has been designed and the experimental results are presented.     

Broadband microstrip patch antennas for MMICs

A broadband microstrip patch antenna well suited for monolithic microwave integrated circuits (MMICs) is presented. The antenna exhibits a measured bandwidth of 35%, low surface wave loss, a high front-to-back ratio, and is fabricated directly on the MMIC substrate material. The predicted and measured input impedances are given along with the measured radiation performance     

Slot-coupled DR antenna for dual-frequency operation

To achieve dual-band operation or wider bandwidth, a new configuration of dielectric resonator antenna is proposed. This structure consists of two rectangular dielectric resonators displaced near two edges of a single slot in the ground plane of a microstrip line. The measured impedance and radiation patterns for two cases are presented. The results for typical examples indicate that an impedance bandwidth twice that of a single element or dual-frequency operation at two separate bands can be achieved     

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.     

Printed elliptical monopole with shaped ground plane for pattern stability

A novel planar elliptical disc monopole antenna for universal mobile communication systems (UMTS) and ultra-wideband (UWB) dual network applications is presented. Printed on a FR4 dielectric substrate and excited by a microstrip transmission line, the antenna has a shaped ground plane featuring a wide impedance bandwidth with excellent omnidirectional pattern stability.     

Broad-band single-patch circularly polarized microstrip antennawith dual capacitively coupled feeds

New design of a circular microstrip antenna with dual capacitively coupled feeds for broad-band circular polarization radiation is presented. The dual feeds are with a small top-loaded disk and are connected to a Wilkinson power divider with a 90° phase shift between its two output feedlines. The radiating circular patch, printed on a thin substrate, is supported by nonconducting posts on a conducting ground plane and is excited capacitively through the dual feeds. With a distance less than 10% times the center operating wavelength between the circular patch and the ground plane, the present proposed antenna can provide an impedance bandwidth (VSWR ⩽2) of about 49% and a 3-dB axial-ratio bandwidth of about 35%. The antenna gain bandwidth, defined to be within 1-dB gain variation in the axial-ratio bandwidth, is as large as 28%, with the antenna gain level at about 7.0 dBi     

基于Polys try介质基板微带天线的应用研究

针对传统贴片天线检测频率有限(2~35 GHz)且由于增益低导致检测结果不明显的问题,文中提出了以聚苯乙烯作为介质基板构建微带天线的解决方案。在以介电材料玻璃超细纤维为介质基板的理论基础上,采用高分子材料Polysty作为介质基板构建微带天线模型。结合经典天线理论计算辐射贴片以及介质基板尺寸;基于HFSS搭建Polysty作为介质基板的模型并根据微带天线特性将理论设计的微带天线参数进行优化,最终得到在1 GHz时微带天线的最佳尺寸。仿真及实验结果表明,Polysty作为介质基板的微带天线中心频率可以达到1 GHz,增益高并且检测角度范围大。     

Circular Polarization in Defected Hexagonal Shaped Microstrip Antenna

A novel circular polarization (CP) design of a single-feed Hexagonal shaped microstrip antenna for enhanced antenna parameters is presented. The CP design is obtained by placing three isosceles triangular defects at proper locations in the hexagonal radiating patch as well as in the square ground plane. By adjusting one of the side lengths of the triangular defect, slightly longer or shorter than that of the others, two orthogonal near degenerate resonant modes for CP radiation are excited. Moreover, the 3 dB axial ratio bandwidth is surrounded by the 10 dB impedance bandwidth, to ensure that the antenna radiates CP waves in its impedance band. The antenna gain of the proposed antenna has increased by 5.34 dB (7.93 vs. 2.59 dB), as compared to the hexagonal microstrip antenna with triangular truncations in patch but without triangular defects in the ground plane having same substrate material, height and same radiating patch size and shape. Prototype antenna is fabricated for experimental evaluation. Simulated and measured results are in good agreement with each other.     

Patch antennas on externally perforated high dielectric constantsubstrates

Smaller physical size and wider bandwidth are two antenna engineering goals of great interest in the wireless world. To this end, the concept of external substrate perforation is applied to patch antennas in this paper. The goal was to overcome the undesirable features of thick and high dielectric constant substrates for patch antennas without sacrificing any of the desired features, namely, small element size and bandwidth. The idea is to use substrate perforation exterior to the patch to lower the effective dielectric constant of the substrate surrounding the patch. This change in the effective dielectric constant has been observed to help mitigate the unwanted interference pattern of edge diffraction/scattering and leaky waves. The numerical data presented in this paper were generated using the finite-difference time-domain (FDTD) technique. Using this numerical method, a patch antenna was simulated on finite-sized ground planes of two different substrate thicknesses, with and without external substrate perforation. The computations showed the directivity drop in the radiation pattern caused by substrate propagation was noticeably improved by introducing the substrate perforation external to the patch for the case of a patch antenna on a relatively thick substrate without any loss of bandwidth. Measurements of a few patch antennas fabricated on high dielectric constant substrates with and without substrate perforation are included for completeness. Good correlation between the computed results and measurements is observed     

Broadband probe-fed patch antenna with a W-shaped ground plane

A new design of a broadband probe-fed patch antenna with a W-shaped ground plane is presented. The W-shaped ground plane is obtained by bending the conventional planar ground plane into an inverted V-shape, seen in the resonant direction of the patch antenna and then adding proper flanges at the two straight edges of the bent ground plane. The proposed design is applicable to the patch antenna with a planar radiating patch with a thin air substrate. With the use of the proposed W-shaped ground plane, the required probe-pin length in the substrate remains small, although the effective substrate thickness is significantly increased, resulting in a much wider operating bandwidth. Also, by choosing proper dimensions of the W-shaped ground plane, the antenna gain for frequencies over the obtained wide bandwidth is enhanced, compared to the conventional patch antenna with a planar ground plane. In addition, the cross polarization is also reduced for the proposed design and the cross-polarization level (XPL) in the H-plane pattern can even be better than that of a conventional probe-fed patch antenna with a thin air substrate     

Grounded dielectric slab finite size effect on patch antenna radiation patterns

The influence of the grounded dielectric substrate finite size on the surface-wave propagation in a microstrip patch antenna is investigated. A simple model that interprets this phenomenon is developed. To reduce surface mode levels and to improve the antenna gain and the radiation pattern, an electromagnetic bandgap structure consisting of a two-dimensional periodic pattern of circles etched in the ground plane of the antenna is adopted.     

Small patch/slot antenna with 53% input impedance bandwidth

A small microstrip patch/slot antenna, which achieves a very large bandwidth on a relatively thin substrate (about 0.01lambda₀), is presented. The performance is achieved by employing a combination of annular-ring loading on the patch radiator and the use of a crossed-slot for miniaturisation. An additional ring-slot in the ground plane is used to produce the wideband characteristics of the antenna. Simulated and measured results indicate that a 53% fractional impedance bandwidth is achieved with respect to the centre frequency of 1.409 GHz and the size of the antenna is reduced by 50% compared to the conventional circular patch antenna with respect to a given frequency     

64 单元X 波段高增益圆极化微带阵列天线设计

采用双层矩形贴片加切角的结构设计圆极化单元,并将其组成应用于X 波段64 单元高增益圆极化微带阵列天线。天线基板采用Taconic-TRF,介电常数4. 5,厚度0. 81mm,损耗角正切0. 0035。利用Ansoft HF-SS 软件对单元及阵列模型进行仿真优化。通过实际测试,64 单元阵列天线轴比AR<6dB 的带宽500MHz,增益达到21. 2dB,S11 <-10dB 的相对阻抗带宽达到6. 9%,天线具有良好的圆极化和阻抗匹配特性。圆极化天线具有较强的抗干扰能力,可很好地应用于电子侦察、电子对抗等领域。设计的圆极化微带阵列天线为组成更大阵列的天线以及构建相控阵天线提供了单元基础。     

基于人工电磁材料的微带贴片天线频带展宽

提出一种以人工电磁材料作为介质基板的矩形微带贴片天线。通过改变人工电磁材料各单元的几何尺寸来控制介质基板的参数变化,以构成非均匀介质基板,使得贴片辐射边的辐射性能提高,从而有效提高了带宽。对设计的非均匀介质微带天线使用HFSS软件仿真。结果表明,普通均匀介质微带天线电压驻波比VSWR≤2时带宽只有0.5GHz,相对带宽为6.7%,而以人工电磁材料为非均匀介质基板的微带天线VSWR≤2时带宽达到1.6GHz,相对带宽达到20.0%。