A modified contour Integral analysis for Sierpinski fractal carpet antennas with and without electromagnetic band gap ground plane

A modified contour integral method coupled with segmentation method has been used, for the first time, to analyze both the Sierpinski fractal carpet (SFC) antennas of different orders and an SFC antenna with electromagnetic band gap (EBG) ground plane. The close agreement between the calculated and measured results for resonant frequencies and input return losses indicates that this technique can be used to accurately predict the impedance characteristic. A novel stacked microstrip Sierpinski carpet fractal antenna using the EBG ground plane is also presented. Comparing to an ordinary microstrip fractal antenna, which has a maximum bandwidth of approximately 2%, the proposed antenna has a higher input impedance bandwidth of nearly 9%. The radiation patterns of the proposed antenna are improved due to the removal of unwanted radiation caused by the surface wave. The experimental measurement results of the proposed antenna are presented in this paper.     

Analysis of circularly polarized square ring and crossed-strip microstrip antennas

Segmentation technique coupled with cavity model have been used to analyze square ring and crossed-strip microstrip patch antennas for circular polarization. This technique is found to predict the characteristics of antennas correctly, as is evident from the close agreement between the calculated and measured results for resonant frequency, input impedance, radiation patterns, and bandwidth. Square ring antenna has been found to have larger impedance bandwidth and axial ratio bandwidth because of lowerQ. Crossed-strip antenna has larger size and thus fabrication tolerances can be relaxed.     

Compact CPW-fed monopole antenna for 5 GHz wireless application

A compact and simple coplanar waveguide (CPW)-fed monopole antenna for 5 GHz wireless communication is proposed. By properly adjusting the lengths of both the monopole strip and the inverted L-shaped ground, the designed antenna, with, including ground plane, only 9/spl times/9.5 mm/sup 2/, can operate at the desired 5.2 or 5.8 GHz band. The electromagnetic coupling effect between the radiating strip and the ground on excitation of the resonant mode has been studied. Prototypes of the proposed antenna have been constructed and experimentally studied. Measured results show a -10 dB impedance bandwidth and an average antenna gain of 400 MHz and >6 dBi, respectively.     

New Half-Hemispherical Dielectric Resonator Antenna for Broadband Monopole-Type Radiation

A new half-hemispherical dielectric resonator antenna (h-HDRA) is proposed and a two-element h-HDRA configuration is employed to design a broadband monopole-type radiator. Two half sections of a hemispherical DRA are employed to enhance the impedance bandwidth by introducing an additional resonant mode. Since the new geometry of an h-HDRA is studied here for the first time, it is characterized using simulation and experimental studies. Two closely spaced resonant modes, which in a two-element h-HDRA generate monopole-type radiation are investigated. Results for both the single and two-element h-HDRAs are presented. As much as 35% impedance bandwidth (S₁₁<-10dB) with more than 5 dBi peak gain, 99.08% efficiency and monopole-type radiation pattern has been demonstrated using a prototype occupying a compact volume measuring 0.48lambda₀ by 0.2lambda₀ approximately, lambda₀ being the wave length corresponding to the center of the impedance bandwidth     

Broadband calculable dipole reference antennas

A broadband calculable standard dipole antenna has been developed, with an uncertainty in the antenna factor (AF) of better than ±0.15 dB at the resonant frequency, f_res, in the frequency range 30 to 500 MHz and ±0.2 dB in the range 600 MHz to 1 GHz. For broadband operation of the dipole resonant at 60 MHz the uncertainty is ±0.2 dB over a range 0.33 f_res to 1.83 f_res. These uncertainties have been validated by close agreement of the measured insertion loss between dipole antennas above a conducting ground plane, with the loss predicted by analytical and numerical methods. The AF measured by the two-antenna method also agrees with the calculated AF. The technique was applied to reference monopole antennas for which AF was determined to an uncertainty of ±0.2 dB over the frequency range 10-100 MHz. The key achievements are: the construction of a very large and flat ground plane, validation of numerical versus analytical calculations of impedance and effective length of resonant dipoles, excellent agreement between measurements and method-of-moments calculations of the coupling between resonant dipoles, good agreement over a broad bandwidth, careful design of antennas and supports, and precision measurements     

Analysis of the microstrip disk antenna element

The circular microstrip antenna element is formed by a radiating disk closely spaced above a ground plane. It is modeled as a cylindrical cavity with magnetic walls which can be resonant in the transverse magnetic (TM) modes. The far fields and the radiation conductances for different mode structures have been calculated assuming a magnetic line current flowing along the perimeter of the disk. The directivity of a disk antenna excited in the dominant mode is between 4.8 dB and 9.9 dB, depending on the size. Losses, due to imperfect supporting dielectrics and to the finite conductivity of the conductors, have been derived by means of a perturbation technique. Graphs are given for design purposes showing the input impedance, theQfactor, and the radiation efficiency at resonance for different modes and thicknesses. The air-filled microstrip antenna has the highest efficiency and the broadest bandwidth at a given resonant frequency.     

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 planar antenna with parasitic radiator

A novel kind of planar monopole broadband antenna with a parasitic radiator is presented. Measurements show that the bandwidth of the monopole antenna has been considerably improved with a parasitic element earthed with a matching inductor. The achieved impedance bandwidth reaches over 85% for VSWR/spl les/2, and the measured radiation patterns have little distortion when the frequency changes. The impedance bandwidth parameters are compared for different dimensions of ground planes     

A wideband low noise amplifiers design incorporating the CMRC circuitry

An impedance bandwidth enhancement technique for tuning a low noise amplifier (LNA) is presented. With the use of the compact microstrip resonant cell (CMRC) at the emitter pins of a bipolar junction transistor (BJT), the impedance bandwidth achieved is about 95%, for a simple single stage amplifier design. The LNA attains a gain of about 15 dB; also a low noise figure of 1.16 dB at 2.1GHz and an average noise figure of about 1.5 dB across the operation bands have been achieved.     

基于互补分裂谐振环的十字缝隙贴片天线（英文）

A compact patch antenna is designed, which is with structures of cross-shape slot, Complementary Split Ring Resonator(CSRR), and loaded transmission line. To implement the compactness in size, these structures are etched on the ground plane, then the input impedance has been improved. The CSRR is employed to improve impedance matching between the source and radiation patch, and the cross-shape slot on the radiation patch is utilized to increase the bandwidth. The design is validated by compariso...     

A New Compact Microstrip-Fed Dual-Band Coplanar Antenna for WLAN Applications

A novel compact microstrip fed dual-band coplanar antenna for wireless local area network is presented. The antenna comprises of a rectangular center strip and two lateral strips printed on a dielectric substrate and excited using a 50 Omega microstrip transmission line. The antenna generates two separate resonant modes to cover 2.4/5.2/5.8 GHz WLAN bands. Lower resonant mode of the antenna has an impedance bandwidth (2:1 VSWR) of 330 MHz (2190-2520 MHz), which easily covers the required bandwidth of the 2.4 GHz WLAN, and the upper resonant mode has a bandwidth of 1.23 GHz (4849-6070 MHz), covering 5.2/5.8 GHz WLAN bands. The proposed antenna occupy an area of 217 mm² when printed on FR4 substrate (epsiv_r=4.7). A rigorous experimental study has been conducted to confirm the characteristics of the antenna. Design equations for the proposed antenna are also developed     

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.     

Wideband small patch antenna

A small patch antenna fed by a coaxial probe with a wideband characteristic is presented. By employing dual shorting pins and cutting a slot in the patch, the size of the patch antenna is reduced while its impedance bandwidth is enhanced. The resonant frequency can be reduced by /spl sim/75% when compared with the resonance edge of a conventional patch antenna. The antenna has an impedance bandwidth of 21.5% (SWR<=2) and maximum gain of 2.2 dBi.     

Stacking resonators to increase the bandwidth of low-profile antennas

A method of increasing the bandwidth of low-profile cavity-hacked slot and microstrip patch antennas without appreciably adding to the antenna dimensions is presented. This idea incorporates the stacking of structures which have close resonant frequencies. Energy is coupled between cavities via carefully placed slots in the common wall. An approximate two-and-a-half fold increase in input impedance bandwidth has been observed for a certain cavity-backed slot antenna.     

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.     

Computer-aided Design Of Stripline Ferrite Junction Circulators

A general design procedure is presented for stripline Y-junction circulators employing solid dielectric between ground planes. The resonator design and impedance matching are derived in a form suitable for computer evaluation. The procedure is applicable to cases where either the circulator bandwidth or the ground plane spacing is specified. An experimental S-band switching circulator illustrates the technique.     

Fourier Transform Domain Analysis of High <Emphasis Type="Italic">T</Emphasis><Subscript><Emphasis Type="Italic">c</Emphasis></Subscript> Superconducting Rectangular Microstrip Patch over Ground Plane with Rectangular Aperture

A rigorous full-wave analysis in the Fourier transform domain is carried out in order to obtain the resonant frequencies and half-power bandwidths of the high T _c superconducting rectangular microstrip patches over ground planes with rectangular apertures. To include the effect of the superconductivity of the microstrip patch in the full-wave analysis, a complex surface impedance is considered. This impedance is determined by using London’s equation and the two-fluid model of Gorter and Casimir. The validity of the solution is tested by comparison of the computed results with previously published data. Variations of the resonant frequency with the high T _c superconducting film thickness are presented. Results showing the effect of the temperature on the resonant frequency and half-power bandwidth of the superconducting microstrip antenna with a rectangular aperture in the ground plane are also given. Finally, a comparison between the efficiency of two antennas is presented. For the first antenna, YBCO patch with YBCO ground plane are considered. For the second antenna, the patch and the ground plane are with copper.     

一种新型U型槽宽频微带天线

提出一种新型的低剖面宽带开槽微带天线。该天线通过U型槽加载,从而产生新的谐振点,达到展宽带的目的。采用HFSS软件对提出的天线模型进行仿真优化,结果显示,该天线在12.83 GHz、15.06 GHz两个频点产生谐振,天线阻抗带宽达到940 MHz和770 MHz     

A novel power plane with integrated simultaneous switching noise mitigation capability using high impedance surface

A novel technique for suppressing power plane resonance at microwave and radio frequencies is presented. The new concept consists of replacing one of the plates of a parallel power plane pair with a high impedance surface or electromagnetic band gap structure. The combination of this technique with a wall of RC pairs extends the lower edge of the effective bandwidth to dc, and allows resonant mode suppression up to the upper edge of the band-gap. The frequency range for noise mitigation is controlled by the geometry of the HIGP structure.     

一种宽频带方形槽圆极化天线设计

文中提出了一种加载微扰元素的新型宽频带圆极化方形槽天线,它由一个倒L 型微带馈电线、一个L 型枝节、一对矩形槽和一个方形槽地板组成。用这些缝隙槽和枝节作为微扰元素来调节天线表面电流分布,可以激 发出多个圆极化谐振模式,从而实现了宽频带圆极化辐射。为了验证其合理性,加工并测试了天线模型。测量结果 表明,实测小于-10 dB 的阻抗带宽为74. 9%,小于3 dB 的轴比带宽为84. 7%。此外,测量和仿真的峰值增益分别为 4. 88 dBi 和4. 86 dBi。因此,文中设计的圆极化方形槽天线具有宽的圆极化带宽特性。