基于多模谐振的低剖面宽带贴片天线

为了增加贴片天线的工作带宽和改善其辐射特性,提出了一种基于多模谐振的低剖面贴片天线。通过在矩形贴片的非辐射边加载短路壁降低H面的高交叉极化,在贴片下方加载短路销钉提高TM_1/2,0模式的谐振频率（f_1/2,0）;然后在TM_3/2,0模式的零电流位置处切割一个矩形缝隙来激发辐射缝隙模式（TM_RS）,得到低剖面、宽频带和低交叉极化的三模谐振贴片天线;最后通过增加贴片宽度和调整天线结构,降低TM_1/2,2模式的频率（f _1/2,2）,实现了四模谐振。仿真和实测结果表明该四模谐振贴片天线在0.03λ₀的厚度下可将带宽增加到21.7% (2.67～3.32 GHz).     

Microstrip antenna on a conical surface

A theoretical analysis of microstrip antennas on conical conducting surfaces is presented. The resonant frequency, input impedance, radiation pattern, quality factor, and efficiency are obtained for a general geometry. Numerical results for a patch antenna with a cone angle &thetas;₀=33.88° operating in the fundamental TM₀₁ mode are shown     

Analysis of the cylindrical-rectangular patch antenna

An analysis is presented of a thin cylindrical-rectangular microstrip patch antenna. After obtaining the electric field under the curved patch and the resonant frequencies using the cavity model, the far-field is found by considering the equivalent magnetic current radiating in the presence of a cylindrical surface. The input impedance and the total Q-factor are then calculated. Numerical and graphical results are presented to illustrate the effect of curvature on the characteristics of the TM₁₀ and TM₀₁ modes     

一种适用于波束扫描的宽带低剖面介质谐振器天线

近年来,为解决传统介质谐振器天线（dielectric resonator antenna, DRA）体积庞大等问题,新颖的低剖面DRA如介质贴片天线和平面介质天线被提出并迅速成为研究热点.然而,现有的低剖面DRA设计要么平面尺寸较大（>0.5λ0×0.5λ0）,要么带宽较窄（<10%）,限制了它们的实际应用.文中提出了一种具有小型化平面尺寸的宽带低剖面DRA.本天线采用介质贴片设计,顶部为高介电常数的介质贴片,中间为低介电常数的介质基板,底部为缝隙馈电结构.缝隙馈电结构可激励起介质贴片谐振器的基模TE111和高次模TE131两种工作模式,这两种模式的场分布在贴片边缘部分存在基模场强较弱而高次模场强较强的显著区别.本设计巧妙地利用了该区域的模式场强区别,通过略微增加贴片边缘部分高度来显著影响高次模谐振频率而轻微影响基模谐振频率,从而将高次模TE131的谐振频率迅速下拉并与基模TE111的谐振频率靠近合并,在不增大介质贴片平面尺寸的前提条件下获得宽带工作效果.本天线的三维尺寸为0.35λ0×0.35λ0×0.08λ0 (λ0为中心频率处的空气中波长),线极化实物案例测试结果表...     

Broadband U-shaped dielectric resonator antenna with elliptical patch feed

A dielectric resonator antenna formed by a U-shaped dielectric resonator and a conformal elliptical patch feed is proposed for wideband communication applications. Simulated results agree well with measured ones, showing good performance in terms of bandwidth and radiation patterns. The measured impedance bandwidth of S₁₁ < -10 dB is about 72%, covering the frequency range 3.82-8.12 GHz. It has a gain of 4.3-7.6 dBi over the whole operating band with a ground size of about 1.2 lambda₀ times 1.2 lambda₀, lambda₀ being the central operating frequency.     

Patch antenna equivalent to simple monopole

Properties of a circular patch antenna with radiation characteristics similar to those of a resonant monopole are presented. The TM₀₁ mode excited patch on a small ground plane radiates a null on boresight and is easy to match to a 50 Ω line. Applications include mobile vehicle applications and wireless LANs     

Dual-band slot-loaded short-circuited patch antenna

An experimental demonstration of a compact dual-band patch antenna designed using slot-loaded and short-circuited size-reduction techniques is presented. By controlling the short-plane width, the two resonant frequencies, f₁₀ and f₃₀, can be significantly reduced and the frequency ratio (f₃₀/f₃₀) is tunable in the range ~1.6-2.2     

Aperture-coupled thin-film superconducting meander antennas

A thin-film superconducting meander patch antenna coupled by an H-shaped aperture is proposed. It is analyzed using a full wave electromagnetic simulator and the theory of cavity model for microstrip patch antennas. The meander patch was fabricated from a single-sided film of YBCO (YBa₂CU₃O₇) on MgO with a typical transition temperature of 90 K. Simulated results are presented for return loss, radiation pattern, and efficiency and these are shown in good agreement with the results obtained from network analyzer measurements. An array of a number of elements is also proposed for wide-band operation     

Q-factor computation of radiation loss corresponding to surfacewave in a patch circular resonator

The authors present a new approach for the Q-factor computation of radiation loss in a circular patch with surface wave TM₀. The circular patch resonant frequency (f) problem is formulated in terms of an integral equation using the transverse resonance method. First, the computed real part of f is found to compare closely with the published results considering space wave TM₁₁. Next, the Q-factor of the surface wave as a function of physical resonator parameters is presented     

Broadband rectangular microstrip antenna with pair oftoothbrush-shaped slots

A novel broadband design of a probe-fed rectangular microstrip antenna with a pair of toothbrush-shaped slots embedded close to the nonradiating edges of the patch is presented. The proposed broadband design is achieved by the excitation of two adjacent resonant frequencies of the TM₁₀ and TM_δ0 modes (1<δ<2), to obtain a wide operating bandwidth. An antenna bandwidth as large as ~2.6 times that of a conventional rectangular microstrip antenna has also been obtained. Derails of the proposed design and experimental results are presented     

Modified planar inverted F antenna

The design of a modified planar inverted F antenna (PIFA) which is more compact (antenna length <λ₀/8 and antenna height <0.01 λ₀) and has a much wider antenna bandwidth (greater than 10 times that of a simple PIFA) is demonstrated. The reduction in antenna length is achieved by meandering the radiating patch, while the enhanced bandwidth with low antenna height is obtained using a chip-resistor load in place of the shorting post. A typical design of the modified PIFA in the 800 MHz band has been implemented, and experimental results are presented and discussed     

Miniaturized high-temperature superconductor microstrip patchantenna

Experimental as well as computational results are presented for 2.4 GHz microstrip antennas which are miniaturized (total length, 6 mm) by both a new, stepped impedance patch shape and a relatively high substrate permittivity. The antennas investigated were fabricated from YBa₂Cu₃O_7-δ thin films epitaxially grown on single-crystalline LaAlO₃ substrates by pulsed excimer laser ablation or by high-pressure oxygen DC sputtering and, for comparison, from copper on the same substrate material. It is shown that the radiation efficiency of this antenna structure is only about 1% to 6% for copper at 77 K but is increased to values between 35% and 65% for HTS films. From experimental investigations of the power dependence of the antenna gain at 77 K, nonlinearities, especially a sharp drop at a current density of about 2×10⁶ A/cm², were observed     

Resonance in cylindrical-rectangular and wraparound microstripstructures

A rigorous analysis of the resonance frequency problem of both the cylindrical-rectangular and the wraparound microstrip structure is presented. The problem is formulated in terms of a set of vector integral equations. Using Galerkin's method to solve the integral equations, the complex resonance frequencies are studied with sinusoidal basis functions which incorporate the edge singularity. The complex resonance frequencies are computed using a perturbation approach. Modes suitable for resonator or antenna applications are investigated. The edge singularity of the patch current is shown to have no significant effect on the accuracy of the results. It is shown that the HE₁₀ modes of the cylindrical-rectangular and wraparound patches are more appropriate for resonator applications. The HE₀₁ and TE ₀₁ modes of the cylindrical-rectangular and wraparound patches, respectively, are efficient radiating modes     

Characteristics of the cylindrical-circular patch antenna

An analysis of a thin cylindrical-circular microstrip patch antenna is presented. Using the cavity model as a base, formulas are obtained for the far-zone electric field and the input impedance of a coax-fed patch. Numerical and graphical results are given to illustrate the effects of curvature on the characteristics of the TM₁₁ mode     

U-slot circular patch antennas with L-probe feeding

Experimental results for U-slot circular patch antennas with L-probe feeding are presented. Using a foam layer of thickness ~0.1λ₀ as a supported substrate, an impedance bandwidth of 38% (SWR⩽2) and a gain of 6.8 dBi have been achieved. The far-field radiation patterns are stable across the passband     

L-probe proximity-fed short-circuited patch antennas

Experimental results for L-probe proximity-fed short-circuited quarter-wavelength patch antennas are presented. Using a foam layer of thickness ~0.1λ₀, as a supported substrate, an impedance bandwidth of 39% and a gain of >7.0 dBi have been obtained. The far field patterns are stable across the passband     

Broadband triangular microstrip antenna with U-shaped slot

The broadband design of a triangular microstrip antenna with a U-shaped slot is demonstrated. With a foam substrate of thickness ~0.08 λ₀, a slotted triangular microstrip antenna with an operating bandwidth of ~18% is obtained, which is ~1.8 times that of a corresponding simple triangular patch antenna. Details of the antenna design and experimental results are presented     

Effect of microstrip antenna substrate thickness and permittivity:comparison of theories with experiment

A set of measurements of patch antennas on substrates of varying thickness and permittivity, using three types of feeds, is presented. Resonant frequency and resonant resistance are compared with calculated values from the representative theories. The measurements show that erratic results may be obtained for substrates thicker than about 0.02 λ₀, where λ₀ is the free-space wavelength at the resonant frequency. These problems may be related to coax-to-microstripline transitions, but their cause is not yet definitely known. The theoretical models that are compared give reasonably good results for resonant frequency, but none give impedance results that are consistently reliable. It thus appears that further work is needed to develop analytical models that can adequately predict the impedance performance of microstrip antennas on thick and/or high dielectric constant substrates     

On the circular polarization operation of annular-ring microstripantennas

Circular polarization (CP) operation of an annular-ring microstrip antenna with a pair of inserted slits at its fundamental TM₁₁ mode is proposed and experimentally investigated. Two examples of the proposed antenna fed using a microstrip line at the inner and outer patch boundaries are studied. Results show that the proposed antenna can have good CP performance and, moreover, the required antenna size at a fixed CP operation can be much less than that of a conventional circularly polarized circular microstrip antenna operated at the TM₁₁ mode. Details of the proposed antenna for CP operation are described and experimental results of the CP performance are presented and discussed     

Wideband folded shorted patch antenna with low profile

The design and measurement of a low-profile folded patch antenna with a short-circuited element are presented. By introducing dual-resonance, a significantly improved bandwidth of almost 30% for S ₁₁<-10 dB, which ranges from 1.48 to 1.99 GHz, is achieved, while the total profile of the proposed antenna is kept at a very low level of 0.046 lambda₀ only. The impedance matching, radiation patterns and gain curve are measured and illustrated. This antenna is easy to fabricate and its performance is less susceptible to manufacturing errors. Owing to its wideband and low-profile characteristics, it is highly suitable for applications in mobile communication systems, such as PCS, DECT and PHS