Microstrip Sierpinski fractal carpet for slot antenna with metamaterial loads for dual-band wireless application

The compact microstrip antennas with the dual-band characteristic and reconfigurable qualification have been noticed and investigated in this paper. We have developed the slot microstrip antenna with Sierpinski carpet and Minkowski formations and then the metamaterial loads are placed on this antenna in the slot area. The reflection/transmission method has considered to obtain the permittivity and permeability of the split ring resonator (SRR) as a metamaterial. Finally, we show that by using some junction in the metamaterial layer, we can obtain reconfigurable characteristic. Both antennas have dual-band characteristic where the first antenna has two resonances at 3.2 and 4.5 GHz and in the second antenna by altering the metamaterial layer both resonances are occurring at 3.5 and 5.8 GHz. We show that the antenna has two resonance frequencies that matched with the metamaterial Double Negative (DNG) characteristic. Both antennas are printed on FR-4 also we compared measurement and simulation results together. Aforementioned antennas cover the main wireless, WiMAX and LTE bands with sufficient gain and high efficiency (more than 80% typically) with a bi-directional radiation pattern for the indoor application. Here, the metamaterial is used for controlling the resonances and Sierpinski carpet is developed for matching.     

A flush-mounted multifunctional slot aperture (combo-antenna) for automotive applications

Two novel antennas: a variable growth, two-arm slot spiral and an annular slot are combined into a single, multicavity backed configuration. The spiral occupies the center/interior region and operates as a second mode circularly polarized (CP) antenna at 2.339 GHz. The annular slot occupies the outer region (at the periphery of the spiral) and is designed to operate as an omnidirectional vertically polarized antenna at 1.472 GHz. This combo antenna is intended for automotive applications and it was designed using the finite element-boundary integral method. Its performance was verified experimentally in a stand alone configuration and while mounted on a vehicle platform.     

On the Dual-Band DRA-Slot Hybrid Antenna

A dielectric resonator antenna (DRA) is placed on top of a slotted cavity to form a hybrid dual-band antenna. The zonal slot cut onto the cavity is fed by an embedded L-probe, whereas the DRA is fed by a coupling rectangular slot cut on the top face of the cavity. It is found that the resonance frequencies of the zonal slot and DRA are primarily dependent on the zonal slot and the DRA, respectively, which greatly facilitates the dual-band design. To demonstrate the idea, the proposed hybrid dual-band antenna is designed for IEEE802.11a/b WLAN applications. The reflection coefficient, radiation pattern, and gain of the dual-band antenna are studied, and the simulation and measurement are in reasonable agreement. A parametric study of the proposed configuration was carried out to characterize the antenna.     

Low Profile Miniaturized Planar Antenna With Omnidirectional Vertically Polarized Radiation

A novel miniaturized cavity-backed composite slot loop antenna (CBCSLA) with low profile and omnidirectional radiation similar to a short dipole is presented. The antenna displays vertical polarization while having less than lambda/100 dimension in height. The geometry of the antenna is inspired from a small magnetic loop which is realized using a slot configuration on metallic ground. Since a small slot loop antenna cannot be impedance matched, a composite geometry is devised that acts like as a small slot loop and can easily be impedance matched using this configuration. The diameter of the CBCSLA can be made as small as lambda/10 or smaller. The feeding mechanism is designed in a manner to create a circumferentially-constant current distribution around the composite loop while effectively matching to a 50 Omega coaxial feed from the antenna center. Additional methods are discussed to further enhance the bandwidth and achieve a dual-band response. The antennas are designed, fabricated, and measured. It is shown that despite their small lateral dimension and extremely small height, the miniaturized cavity-backed slot loop features extremely well input impedance match, uniform radiation pattern, low cross-polarization levels and expected gain.     

Multiband Microstrip-Fed Right Angle Slot Antenna Design for Wireless Communication Systems

This paper presents a novel multiband microstrip-fed right angle slot antenna design technique for multiple independent frequency bands. The new technique uses various slot sizes at various appropriate positions. We first propose a tri-band slot antenna consisting of three right angle slots. Then, a quad-band slot antenna is developed with four right angle slots which achieves slant ±45° linear polarization, omnidirectional pattern coverage, good antenna gain, and acceptable impedance bandwidths over all the operating frequency range. Moreover, an open-circuited tuning stub is introduced to achieve good impedance matching. Both proposed antennas are designed on a ground plane of RT/duroid 5880 substrate with a thickness of 1.575 mm. The real measurable results show that the desired frequencies used in wireless communication systems, namely, WLAN and WiMax, are efficiently achieved.     

基于超表面的天线多波束偏转技术研究北大核心CSCD

5G移动通信对天线提出了多极化、多频段、多波束等更高的技术需求。超表面具有很强的电磁调控能力,利用这一特性可以实现天线多波束偏转。本文首先提出新型的基于行波激励网络的双波束偏转方法,利用超表面实现定向波束可控,设计了单频低副瓣高增益的双波束超表面天线。其次,提出基于多相位自由度理论的双频行波激励网络,结合双频超表面,设计了双频双波束偏转角可独立控制的超表面天线。在此基础上,提出基于正相位响应理论的稳定波束偏转角的方法,设计了具有稳定波束的±45°双极化超表面天线。与传统多波束方法相比,本方法省略了复杂的波束形成网络,设计简单、结构紧凑,而且能够实现双频、双极化等特性,可为新一代移动通信天线的研制提供技术思路。     

A novel antenna concept for future solar sails: application of Fresnel antennas

Recent studies have shown that interplanetary missions may be made possible using inflatable solar sails that employ solar-flux power, providing thrust for spacecraft while reducing onboard fuel requirements. These sails require a large surface area (i.e., 100 m in diameter) to capture enough solar flux for spacecraft navigation. In this paper, a novel communication antenna concept is proposed for future solar-sail missions, taking advantage of the large sail surface area via application of Fresnel-zone (FZ) antennas. This study focuses on utilizing a design/analysis methodology using physical optics (PO) and method of moments (MoM) for Fresnel-type antennas applicable to the solar-sail missions. Extensive parametric studies of Fresnel-zone antenna radiation characteristics have been performed, and the analytical methodologies were verified using a series of measurements. Fresnel-zone antenna gain is studied under different antenna configurations. Furthermore, a Fresnel-zone antenna under surface deformation is investigated to characterize Fresnel-zone antenna performance in the reflective mode. In addition, a new bandwidth-enhancement technique is introduced for Fresnel-zone antennas, to accommodate the dual-band operation ( X band uplink and downlink) of the antenna for the deep space network (DSN).     

Design and experimental investigation of stripline antennas

The results of development and experimental investigation of several centimeter-wave planar antennas are presented. The antennas contain a multichannel stripline power divider and a 2D periodic array of slot radiators excited by symmetric strip lines. A single-polarization antenna, an antenna with two linear polarizations, and an antenna with two circular polarizations are analyzed. The results of measuring the basic parameters of these antennas (the gain, the radiation pattern, and the cross-polarization level) are presented. Specific features of the design of such antennas and possible means of improvement of their performance characteristics are discussed.     

Miniaturised reconfigurable window slot antenna using mechanical tuning

A novel design approach of varying the slot width on radiating patch of a microstrip antenna for achieving reconfigurable dual-band operation is proposed. The design of this miniaturised reconfigurable antenna is done without the use of active switches or MEMS. The dual band is obtained by rotating the strips on the patch creating slots and varying the slot width using mechanical tuning. The strip is rotated in angular position from 0° to 90° varying the slot width that alters the resonant frequency of the antenna making it resonate at different frequencies covering the wireless bands for global system for mobile communication, global positioning system, wireless local area network and Bluetooth. This antenna provides a dual-band operation that shifts over the bands depending upon the slot width. This antenna achieves the bandwidth requirement and gain in the bands of operation. The effect of change in slot width on the radiation pattern is also discussed. The prototype antenna is fabricated and tested to prove the proposed concept of design. The measured results are in agreement with the simulated results.     

Spatial power combining for two-dimensional structures

The two-dimensional (2-D) hybrid dielectric slab-beam open and closed waveguide systems are suitable for the design of planar quasi-optical integrated circuits and devices. An open system consisting of an active E-plane amplifier array consisting of Vivaldi-type antennas with MESFET and monolithic microwave integrated circuit (MMIC) devices was investigated. The 4×1 MESFET amplifier array generated 11 and 4.5 dB of amplifier and system gain, respectively, at 7.12 GHz, and the cascade MMTC Vivaldi-type antenna produced 24 dB of amplifier gain at 8.4 GHz. Also, experiments on a new 2-D H-plane parallel-plate closed system with a stripline slot antenna is introduced, and the wavebeam-mode theory is presented. The new system minimizes scattering and isolation losses associated with open structures. The amplifier gain of the closed system based on slot antennas is compared to the open system based on Vivaldi antennas     

微带线-槽线馈电缝隙等角螺旋天线设计

被动雷达导引头为探测与跟踪目标可采用宽带等角螺旋天线,针对降低等角螺旋天线剖面,该文提出一种低剖面背腔式微带线-槽线馈电缝隙等角螺旋天线。微带线-槽线巴伦(Balun)中渐变微带线将同轴线激励的不平衡电场最终转化为槽线处平衡电场。实测结果表明,该缝隙等角螺旋天线实现了1:9的电压驻波比(VSWR)带宽,良好的辐射方向图与圆极化特性。在天线背面加入高度仅有0.05L(L为最低工作频率所对应自由空间中波长)的反射腔,腔内放置矩形环状吸波材料,有效拓展了天线低频段带宽。测试结果表明带有反射腔的缝隙等角螺旋天线实现了1:6.4的电压驻波比带宽,天线增益大于4 dB,良好的圆极化与方向图特性。平面化、一体化的馈电方式与低剖面反射腔有效降低了缝隙等角螺旋天线剖面,测试结果验证了该文所提出的微带线-槽线巴伦馈电缝隙等角螺旋天线设计方法的有效性。     

Design of a dual-band coplanar waveguide-fed slot antenna with wide frequency separation

This paper presents a novel design for a dual-band coplanar waveguide-fed-slot antenna that operates at 27GHz and 39GHz. Matching this antenna at the two widely separated frequencies is achieved using a special matching network of slot antennas. Experimental and numerical results are presented for the return loss and radiation patterns of this antenna.     

Dual-Band Circularly Polarized Dual-Slot Antenna With a Dielectric Cover

A new circularly-polarized (CP) dual-slot antenna fed by a single L-probe is proposed for dual-band applications. The antenna consists of a zonal slot and an annular slot, both of them being cut onto a square conducting cavity with a protective dielectric cover. It is observed that the resonance frequencies of the lower and upper bands are controlled by the zonal and annular slots, respectively, making designs of the dual-band antenna very easy. To demonstrate the idea, the proposed antenna was designed at 2.4/5.8 GHz for two IMS bands. The reflection coefficient, axial ratio, radiation pattern and gain of the dual-band antenna were studied, and reasonable agreement between the simulated and measured results was obtained. A parametric study was carried out to characterize the proposed antenna.      

Frequency Reconfigurable Antennas Design for Cognitive Radio Applications with Different Number of Sub-bands Based on Genetic Algorithm

This paper proposes frequency reconfigurable antennas using genetic algorithm, suitable for cognitive radio applications. The optimization is applied to find the slot shape and the switches locations in the ground plane of monopole antennas for adjustment of the bandwidth. We introduce a new cost function appropriate for designing antennas for cognitive radio applications. In the first design, the presented antenna can operate in the band of 1.9–3.8 GHz and two sub-bands 1.8–2.78 and 2.78–3.8 GHz using the possible minimum number of switches. In the second design, the proposed antenna works in a wide operating band of 1.85–4 GHz and three different sub-bands 1.72–2.27, 2.27–2.9 and 2.9–3.75 GHz. The proposed antenna with three modes of operation is fabricated and the comparison of the simulated and measured results shows a good agreement.

     

Dual-band CPW-fed folded-slot monopole antenna for RFID application

A folded slot with open end is introduced to achieve a dual-band coplanar waveguide (CPW)-fed monopole antenna for radio frequency identification (RFID) applications. The designed antenna, which, including the substrate, is only 32 mm in height and 20 mm in width, can operate simultaneously at the 2.45 and 5.8 GHz bands with -1.8 and 2.3 dBi gains, respectively. Its properties make the antenna suitable for RFID tags     

新型共口径双频双圆极化微带天线设计

论述了一种共口径双频双圆极化微带天线的设计方法。通过工作于主模和高次模的两辐射贴片嵌套来实现双频双圆极化辐射和满足双馈电端口高隔离度的要求。依据此设计方法按照内外贴片不同频段分配研制了两种天线实物样机,并对天线样机的电性能进行了测量,测量结果表明,天线在两频段上圆极化性能良好,并且双端口隔离度高于35dB,证明了此设计方法的有效性。     

Switched WLAN-wideband tapered slot antenna

A switched band antenna that has a capability to operate in dual-band WLAN mode (2.4-2.485 GHz and 5.725-5.875 GHz), a single band WLAN mode of 2.4-2.485 GHz and a wideband mode (2.2-7.2 GHz) is presented. The antenna is based on a tapered slot antenna, which has a defected ground structure containing two switchable ring and two rectangular slots to provide a switched band property. Measurement results on a prototype antenna, with an ideal switch, fully demonstrate the performances of the proposed designs. The proposed antenna is suitable for use in a base station or an access point for WLAN and wideband applications and may be also useful in future multimode radio systems.     

EBG 结构改善天线辐射特性初步研究

本文研究了高阻表面型EBG,其蘑菇形二维周期结构具有紧致特性,周期和单元尺寸远小于工作波长,非常适 合于阵列天线设计,它的表面波抑制特性有助于改善天线性能。采用Mushroom-like EBG 结构形式,针对12GHz 频率完成 初始结构参数选取,利用同轴探针模型给予验证。随后加载于波导缝隙阵列,采用HFSS 模拟软件,通过优化设计,降 低了方向图副瓣及后瓣,其中对第二副瓣和后瓣的抑制优于2dB,前向辐射也有所增加,达到了改善天线辐射特性的目的。     

一种新型垂直极化同轴波导缝隙天线

结合波导缝隙和同轴线结构,提出了一种新型同轴波导缝隙结构实现天线小型化。首先,分析了同轴波导缝隙天线内金属摆线上的电流分布,改进了缝隙形式和摆线设计;然后,利用HFSS软件建立不同缝隙数目的同轴波导缝隙天线模型进行仿真,对比分析驻波带宽和方向图带宽;最后,建立不同缝隙数目的同轴波导缝隙天线有限阵列,对比分析阵列中天线增益和效率。     

A high gain dual-band printed antenna for LTE base stations with a corner reflector

A high gain dual-band printed antenna is proposed for LTE base stations applications. The established 60 × 60 mm² broadband antenna structure is composed of two perpendicular U-shaped and L-shaped monopole antennas which are located vertically on ground plane printed on 1.6 mm thick FR4 substrate. A metallized wall is connected to the substrate which forms a corner reflector. A coaxial cable at the common center of the monopoles is adopted to excite the antenna. Wise implementation of the conductive elements and finely tuning of the monopoles dimensions yield the excitation of two resonances and dual band operation achievement. The presented antenna achieves bandwidths of 1.61–1.86 GHz and 2.25–2.45 GHz suitable for LTE applications. Stable radiation pattern, small size, cost effective fabrication, and high peak gain values of 10 dBi and 9.5 dBi at two operating bands are the prominent features of the proposed antenna topology.