Radiation frequencies of ferrite patch antennas

The radiation frequencies of rectangular microstrip patch antenna deposited on ferrite substrate have been measured. Two different radiation modes were found whose frequencies behaved differently under the application of a biasing magnetic field. These two modes of radiation have been identified with a transverse mode whose radiation frequency increased with increasing magnetic field and a longitudinal mode whose radiation frequency decreased with the applied magnetic field. A theoretical model has been formulated for radiation of these two modes based on a multidomain configuration of the ferrite substrate.<>     

Patch antenna fed by shorted coplanar microstrip line

A novel dual-frequency patch antenna fed by a coplanar microstrip line is presented. By embedding a shorting pin in the microstrip feed line, the proposed antenna is capable of operating at two distinct modes with different radiation characteristics: omnidirectional shorting-pin-loaded patch mode and broadside regular patch mode. In addition, the frequency ratio of the two resonant frequencies is also tunable in the range 3.7-2.7 by loading an additional slot in the microstrip patch.     

基于北斗卫星导航系统的一种圆极化微带天线

介绍一种用于北斗卫星导航系统的圆极化微带天线。该天线的主辐射器由开槽的圆形贴片构成,采用单点的同轴馈电,设计的中心工作频率为2．492GHz。仿真结果显示,调节圆形贴片中开槽的长度,可以分离出简并模,激励两个正交的模式,当两个分量相位为90deg,可以实现圆极化。实际测试中,｜S11｜于-10dB的阻抗带宽为0．09GHz,3dB轴比带宽为0．033GHz,与仿真结果基本吻合。     

Comments on “On the resonant frequencies of microstripantennas”

The resonant frequencies of equilateral triangular microstrip antenna calculated by Gang (see ibid. vol.37, no.2, p.245, 1989) are compared with the experimental results of Dahele and Lee (1987). When computing the resonant frequencies of equilateral triangular microstrip antenna, using the same equations proposed by Gang, we obtained different results, which are given, from Gang's results. For an equilateral triangular microstrip antenna, the resonant frequencies obtained from the cavity model with perfect magnetic walls are given by the formula shown. In this work, we suggest a new closed-form expression. We compared our computed values of the resonant frequencies for the first five modes of the equilateral triangular patch antenna with theoretical and experimental results reported by other scientists     

单馈电双模方形微带天线及圆极化实现收稿

基于展开理论,给出了沿贴片对角线馈电时方形微带天线的内场分布和输入阻抗公式.通过在贴片四周切割缝隙,有效地降低了天线双主模的谐振频率并实现了圆极化辐射,讨论了缝隙长度与天线极化之间的关系.为实现微带天线的小型化提供了一种新途径,给出了UHF波段天线设计实例.     

Microstrip circular-segment antenna

The analysis of the electromagnetic properties of the circular-segment microstrip antenna with microstrip feed is presented. The theory employs an equivalent magnetic wall model, treating the antenna as a lossy flat cavity. A series expansion in resonant modes yields an approximation of input impedance, radiation characteristics and near field data of the antenna.     

A numerical study of a dielectric disk antenna above groundeddielectric substrate

An antenna made of a dielectric disk with a high permittivity mounted on top of a grounded dielectric substrate of low permittivity is analyzed. A numerical procedure based on surface integral equations, derived from the equivalence principle, is used to compute the natural resonant frequencies for the HEM₁₁ mode from which the radiation Q factor of the antenna is obtained. Then the radiation pattern of the antenna, operating at the resonant frequency evaluated previously, is computed with an electric dipole excitation located within the dielectric substrate under the dielectric disk. The effect of various parameters on the radiation characteristics of the antenna is studied, and presented in the form of diagrams. The low values of the radiation Q, combined with the high values of the dielectric Q and conductor Q, indicate that this antenna promises to be more efficient then the microstrip antenna     

A New Coupling Mechanism for Circularly Polarized Annular-Ring Patch Antenna

A novel coupling technique for circularly polarized annular-ring patch antenna is developed and discussed. The circular polarization (CP) radiation of the annular-ring patch antenna is achieved by a simple microstrip feed line through the coupling of a fan-shaped patch on the same plane of the antenna. Proper positioning of the coupling fan-shaped patch excites two orthogonal resonant modes with 90 phase difference, and a pure circular polarization is obtained. The dielectric material is a cylindrical block of ceramic with a permittivity of 25 and that reduces the size of the antenna. The prototype has been designed and fabricated and found to have an impedance bandwidth of 2.3% and a 3 dB axial-ratio bandwidth of about 0.6% at the center frequency of 2700 MHz. The characteristics of the proposed antenna have been by simulation software HFSS and experiment. The measured and simulated results are in good agreement.     

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.     

A simple design of planar microstrip antenna on composite material substrate for Ku/K band satellite applications

A straight forward design of rectangular slotted microstrip planar antenna fed by 50 ohm microstrip line is proposed for Ku/K band satellite applications. The radiating patch of the antenna occupies an area of 17 × 17 mm² and fabricated on 1.0 mm‐thick ceramic filled bioplastic composite material substrate whose dielectric constant (ε_r ) is 10.0. The dual resonant square‐shaped antenna has been formed by inserting four arc shape slots at the corners with the combination of circle and square and wide square shape slot at the center. The results from the measured data show that the antenna has a lower resonant mode impedance bandwidth for S11 < −10 dB is of 18.4% (11.67–14.05 GHz) and upper resonant mode bandwidth is of 8.2% (18.19–19.75 GHz) centered at 12.94 GHz and 19.04 GHz, respectively. The antenna prototype has achieved maximum gains of 3.1 dBi and 4.13 dBi with average radiation efficiencies of 75.3% and 86.4% for the lower band and the upper band, respectively. The numerical data analyses of both the measured and simulated results show relatively good agreement. Moreover, the consistent and symmetrical radiation patters of the proposed antenna make it suitable candidate for the Ku/K band satellite applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Printed double-T monopole antenna for 2.4/5.2 GHz dual-band WLAN operations

A novel and simple printed dual-band double-T monopole antenna is proposed. The antenna comprises two stacked T-shaped monopoles of different sizes, which generate two separate resonant modes for the desired dual-band operation. The proposed antenna has a low profile and can easily be fed by using a 50 /spl Omega/ microstrip line. Prototypes of the proposed antenna designed for WLAN operations in the 2.4 and 5.2 GHz bands have been constructed and tested. Good radiation characteristics of the proposed antenna have been obtained. Effects of varying the monopole dimensions and the ground-plane size on the antenna performance have also been studied.     

A 94-GHz aperture-coupled micromachined microstrip antenna

This paper presents an aperture-coupled micromachined microstrip antenna operating at 94 GHz. The design consists of two stacked silicon substrates: (1) the top substrate, which carries the microstrip antenna, is micromachined to improve the radiation performance of the antenna and (2) the bottom substrate, which carries the microstrip feed line and the coupling slot. The measured return loss is -18 dB at 94 GHz for a 10-dB bandwidth of 10%. A maximum efficiency of 58±5% has been measured and the radiation patterns show a measured front-to-back ratio of -10 dB at 94 GHz. The measured mutual coupling is below -20 dB in both E- and H-plane directions due to the integration of small 50-μm silicon beams between the antennas. The micromachined microstrip antenna is an efficient solution to the vertical integration of antenna arrays at millimeter-wave frequencies     

Meshed patch antennas

Conventional microstrip patch antennas are printed with continuous solid copper shapes and ground planes. The general properties of meshed patches are presented in this paper where both the patch itself and the ground plane are meshed. The gain, cross-polarization, bandwidth and radiation patterns are discussed for different combinations of patch and ground plane. The radiation patterns are not significantly affected by meshing the patch alone, but meshing the ground plane increases the back radiation. The gain can suffer by up to 3 dB or more when compared to a standard patch. Cross-polarization is improved providing that the correct mesh line geometry is chosen for the excitation mode. Meshing lowered the resonant frequency in some cases by up to 30% and also improves the bandwidth by a factor of up to 2.5 in some modes. Overall, the meshed patch offers a complex tradeoff between parameters but gives opportunities for improving the bandwidth and reducing the cross polarization and the antenna dimensions at the expense of the gain.     

介质覆盖矩形微带天线的理论与实验

本文研究了介质覆盖矩形微带天线的特性，精确的谱域全波分析方法被扩展到这类天线的分析中，给出了理论计算公式，探讨了介质覆盖层和对矩形微带天线的驻波比的影响，实验结果证实了理论计算的正确性。     

Bandwidth enhancement for dual-frequency microstrip antenna with conical radiation

A design for dual-frequency microstrip antennas with conical radiation patterns is studied. The dual-frequency operation is achieved by exciting two different resonant modes of the square microstrip patch antenna with four symmetrical shorting walls. Then, a method to enhance the impedance bandwidths of the dual-frequency antenna is proposed, and the experimental results show bandwidths are increased by 19 and 31% at the lower and higher operating frequencies, respectively. Simulation analyses are also performed to support the measured results.     

内嵌结构光子晶体在F 型微带天线中的应用

对常用的正方晶格光子晶体结构进行改进优化,设计出一种新型内嵌结构式二维光子晶体,即在普 通正方晶格光子晶体内部嵌入同类晶格的光子晶体。将该结构光子晶体应用到F 型微带天线中,采用平面波展开 法,进行大量仿真计算。结果表明:与传统的微带天线相比,加入该结构光子晶体后的微带天线回波损耗由 -18. 2465dB 降低到-41. 0624dB。天线具有更好的阻抗特性和辐射效率,方向图有所改善,背瓣辐射最大处减少约 5dB。这种新型的光子晶体微带天线达到了提高天线性能的目的。     

Design and Analysis of Triple-Band Rectangular Microstrip Antenna Loaded with Notches and Slots for Wireless Applications

In this paper, a rectangular triple-band microstrip antenna has been designed for Bluetooth application by successively loading notches and slots of different dimension in radiating patch. The conventional microstrip antenna suffers with narrow impedance bandwidth. The current work affords an alternate option to enhance the bandwidth of antenna that resonates in triple-band operation. Initially, the antenna is resonating in single-band but after loading slots, the bandwidth of microstrip antenna has been obtained 1.97% (lower band), 10.35% (middle band) and 33.16% (upper band) resonating in triple-band with three resonant frequency at 1.422 GHz (lower resonant frequency), 1.791 GHz (middle resonant frequency) and 2.467 GHz (higher resonant frequency). The suggested antenna has upper frequency band in the range of 2.045–2.858 GHz resonating at 2.467 GHz frequency and it is appropriate for Bluetooth applications (2.40–2.48 GHz) and both lower band useful for other wireless (L-band) applications. The return loss of upper band is ??34.52 dB at 2.467 GHz. The suggested microstrip antenna is directly fed by 50 ohm microstrip line feed. The suggested antenna has been designed, simulated and analyzed by IE3D simulation software.

     

Frequency independent microstrip stacked antenna

The advancement of technological development in the microstrip antenna and its applications in diverse areas, have given rise to the need for a frequency agile and frequency independent microstrip antenna which could be used for the same range of frequencies without altering the system. Requirements of such nature could be met by log periodic antenna. However, in the present endeavour a frequency independent microstrip stacked antenna consisting of nine elements operating in the S-band (2.000–4.000GHz) has been proposed. The developed antenna has been experimentally tested over an achievable band of frequencies from 3.200 to 3.920GHz. The antenna performance has characteristics like E-plane radiation patterns. The 3dB beamwidth, radiated power and VSWR show very similar behaviour for the different frequencies of operation obtainable in the S-band. The coaxial-fed microstrip stacked antenna provides an operational bandwidth of approximately 23%, i.e. 3.200GHz to 3.920GHz. The VSWR for the entire operational band is around 2 whereas the gain for the antenna is found to vary from 4.00 to 8.36dB. The 3dB beamwidth has been found to fluctuate between 16.8° and 23.5°. The designed antenna can be well suited for the practical broadband applications.     

Intrinsic modes of radiation in ferrite patch antennas

We have found two types of radiation modes for patch antennas loaded with ferrite materials. Each mode of radiation is a linear combination of normal modes of propagation in parallel plate waveguide separated by a slab of ferrite material. We have introduced new boundary conditions in which only TE modes of oscillation in the patch antenna cavity result. According to different propagation directions relative to the applied DC field these TE modes are distinguished as transverse modes and longitudinal modes, and they possess mutually perpendicular radiation polarizations. While the longitudinal TE modes are found to form discrete modes in the frequency domain, the radiation frequency of a transverse TE mode can be continuously tuned over a wide frequency range by varying the biasing magnetic field. Circularly polarized radiations may result from simultaneous excitations of these two modes. Ferrite patch antennas of square geometry have been fabricated and tested. The measured resonant frequencies compared very well with our theory     

Compact microstrip-line-fed ring monopole antenna with tuning strip for 5 GHz WLAN operation

A novel compact and simple microstrip monopole antenna for 5 GHz wireless local area network (WLAN) operation is proposed. To excite a resonant mode in the operating band, a tuning strip is added to the antenna, which consists of a rectangular ring microstrip and a top loaded vertical strip, and is fed by a 50 /spl Omega/ microstrip line. The effects of the added strip to the impedance matching have been studied. A constructed prototype of the proposed antenna has been tested and bandwidth of about 930 MHz ranging from 5.03 to 5.96 GHz, monopole-like radiation pattern, and average gain of greater than 2.6 dBi over the operating band have been obtained.