A TRIBAND SWASTIKA SHAPED PATCH ANTENNA WITH REDUCED MUTUAL COUPLING FOR WIRELESS MIMO SYSTEMS

A novel compact Swastika shaped patch antenna is designed in the present work,which can be used for Multiple Input Multiple Output(MIMO) systems.The proposed two element MIMO system resonates at a triband of 3.3 GHz,5.8 GHz,and 7.1 GHz with an improved impedance bandwidth of 37% and a reduced mutual coupling of-33 dB.These results are better compared to a normal E shaped patch antenna designed with same size and thickness,achieved without using any additional decoupling methods.A 2×2 MIMO system employing the Swastika shaped patch antennas is analyzed using computational electromagnetic ray tracing software for an indoor environment.The results show an improvement in the capacity compared to a 2×2 MIMO system developed with dipole antennas.The proposed antenna is a good choice for MIMO systems operating for several Ultra WideBand(UWB) applications.

A Design of Swastika Shaped Wideband Microstrip Patch Antenna for GSM/WLAN Application

This paper presents a compact microstrip patch antenna at operating frequency of 2.5 GHz. The radiating element of the proposed antenna consists of Swastika symbol patch using dielectric substrate 4.2, loss tangent 0.0012 and having the same substrate height 1.6 mm. The antenna size is very compact (28.8 mm × 37.2 mm × 1.6 mm) and covers 1.696 GHz to 2.646 GHz and can be used for GSM and WLAN applications. Using IE3D software package of Zealand, the designed antenna is simulated. The computer simulation results show that the antenna can realize wideband characteristics having good impedance bandwidth of 43.758% (VSWR ≤ 2) for all resonant frequencies. Our aim is to reduce the size of the antenna as well as increase the impedance bandwidth.

Triple-Band L-Shaped Monopole Antenna with Defected Ground Plane for WLAN and WiMAX Application

This paper presents the simulation and measured results of a triple-band L-shaped monopole antenna with defected ground plane for applications in wireless local area networks（WLANs） and worldwide interoperability for microwave access（WiMAX） bands.The triple-band L-shaped monopole antenna with defected ground plane was fabricated on a FR4 substrate. The lower band is associated with the shorted parasitic strip in the protruding stub of the ground plane; the middle band is expected to be controlled by the longer strip of L-shaped monopole in the front side,while the higher band is associated with the short strip of L-shaped monopole in the front side. The proposed antenna has a good agreement between the measured and the simulation results. It has a 10 d B return loss with the bandwidth of 250 MHz（2270 MHz to 2520MHz） in the lower band, 600 MHz（3320 MHz to 3,920MHz） in the middle band, and 1110 MHz（5030 MHz to6140 MHz） in the higher band. The proposed antenna covers the ISM（industrial, scientific and medical）,HIPERLAN（high performance radio local area network）, UNII（unlicensed national information infrastructure）, and WiM AX bands.

Analysis and Design of a New Shaped Spherical Reflector Antenna with a Horn Feed

A design method of a new shaped spherical reflector antenna with a horn feed for wide-angle scanning is presented,in which the horn's phase center need not be found out and its optimal position can be determined.It is found from numerical calculation that the shaped spherical reflector antenna has better electrical performance than that of the spherical reflector antenna,at the maximum gain value under the conditions of the same feed and reflector aperture,and can be used as a wide angle searching antenna.

Enhancement of Characteristics of Antenna Arrays Employing S-Shaped Resonators

This paper illustrates a simple kind of tri-band printed G-shaped monopole antenna for Multiple-Input-Multiple-Output (MIMO) systems. The proposed antenna is used to achieve three operating frequencies, 2.45 GHz, 5.2 GHz and 8.2 GHz for wireless communications. To improve the isolation between the two radiating elements, we use left-handed materials composed of only S-shaped resonators to get negative refractive index at the three operating frequencies. When one layer of S-shaped resonators is employed, the antenna correlation, the diversity gain and the bandwidth are also enhanced. The simulated results are presented and evaluated with and without left-handed materials.

Double U-Shaped Slots Loaded Stacked Patch Antenna for Multiband Operation

The design of a seven-band stacked patch antenna for the C, X and Ku band is presented. The antenna consists of an H-slot loaded fed patch, stacked with dual U-slot loaded rectangular patch to generate the seven frequency bands. The total size of the antenna is 39.25 × 29.25 mm2. The multiband stacked patch antenna is studied and designed using IE3D simulator. For verification of simulation results, the antenna is analyzed by circuit theory concept. The simulated return loss, radiation pattern and gain are presented. Simulated results show that the antenna can be designed to cover the frequency bands from (4.24 GHz to 4.50 GHz, 5.02 GHz to 5.25 GHz) in C-band application, (7.84 GHz to 8.23 GHz) in X-band and (12.16 GHz to 12.35 GHz, 14.25 GHz to 14.76 GHz, 15.25 GHz to 15.51 GHz, 17.52 GHz to 17.86 GHz) in Ku band applications. The bandwidths of each band of the proposed antenna are 5.9%, 4.5%, 4.83%, 2.36%, 3.53%, 1.68% and 1.91%. Similarly the gains of the proposed band are 2.80 dBi, 4.39 dBi, 4.54 dBi, 10.26 dBi, 8.36 dBi and 9.91 dBi, respectively.

CPW Fed Double T-Shaped Array Antenna with Suppressed Mutual Coupling

A compact CPW-fed double T-Shaped antenna is proposed for dual-band wireless local area network (WLAN) operations. For the proposed antenna, the -10 dB return loss bandwidth could reach about 25.5% for the 2.4 GHz band and 5.7 % for the 5 GHz band, which meet the required bandwidth specification of WLAN standard. To reduce the mutual coupling and get high isolation between two dual-band antennas, we proposed the novel electromagnetic band gap (EBG) structures. When the EBG structure is employed, a -13dB and -30dB mutual coupling reduction is achieved at 2.4 and 5.2 GHz. It shows that the features of small size, uniplanar structure, good radiation characteristics and small mutual coupling are promising for multi-input multi-output (MIMO) applications.

Triple Notched Band Characteristics UWB Antenna Using C-Shaped Slots and Slot-Type Capacitively-Loaded Loop (CLL)

Ultra wide bands antennas with notched bands characteristics have recently been considered for efficient communication between devices. In this paper, a compact ultra-wideband antenna (UWB) for UWB applications with triple bandnotched characteristics is presented. The proposed antenna consists of a square patch with four truncated corners and a partial ground plane with a rectangular slit. The operation bandwidth of the designed antenna is from 2.66 GHz to more than 13.5 GHz. Band-notched characteristics of antenna to reject the frequency band of 3.18 - 3.59 GHz and 4.70 - 5.88 GHz, is realized by inserting two C-shaped slots in the patch, the third band of 9.54 - 12.22 GHz is achieved by slottype capacitively-loaded loop (CLL) inserted in the patch near the feed line. Details of the proposed antenna design and simulated results are presented and discussed.

N Design of an H-shaped Slot Multi-frequency Microstrip Antenna

Conventional slot microstrip antenna is analyzed,an h-shaped multi-frequency and miniaturization slot microstrip antenna is proposed.Numerical simulation is performed for the characteristics of the antenna with the software HFSS11.0,which is a kind of simulation software based on Finite Element Method,the simulation results shown that the antenna operated at 2.26~2.42GHz,2.67~2.82GHz,4.28~4.39GHz and 5.76~5.89GHz when the return loss S11<-10dB,the size reduced compare to general microstrip antenna,demonstrated the effectiveness of the design scheme.The antenna structure is simple and easily to be implemented,met the wireless LAN 802.11a/b/g/n mobile terminal antenna miniaturization and multi-band requirements.

Plus Shape Slotted Fractal Antenna for Wireless Applications

Fractal antennas are characterized by space filling and self-similarity properties which results in considerable size reduction and multiband operation as compared to conventional microstrip antenna. This paper outlines a multiband antenna design based on fractal concepts. Fractal antennas show multiband behavior due to self-similarity in their structure. The plus shaped fractal antenna has been designed on a substrate of dielectric constant €r = 4.4 and thickness 1.6mm. The proposed antenna is characterized by a compact size and it is microstrip feed fractal patch of order 1/3. It is observed that the antenna is radiating at multiple resonant frequencies. The resonant frequency is reduced from 2.2 GHz to 900 MHz after I & II iterations respectively. Thus considerable size reduction of 81.77% & overall bandwidth of 12.92% are achieved. The proposed antenna is simulated using the method of moment based commercial software (IE3D) and it is found that simulated results are in good agreement with the experimental results.

A novel static shape-adjustment technique for planar phased-array satellite antennas

Planar phased-array satellite antennas deform when subjected to external disturbances such as thermal gradients or slewing maneuvers.Such distortion can degrade the coherence of the antenna and must therefore be eliminated to maintain performance.To support planar phased-array satellite antennas,a truss with diagonal cables is often applied,generally pretensioned to improve the stiffness of the antenna and maintain the integrity of the structure.A new technique is proposed herein,using the diagonal cables as the actuators for static shape adjustment of the planar phased-array satellite antenna.In this technique,the diagonal cables are not pretensioned;instead,they are slack when the deformation of the antenna is small.When using this technique,there is no need to add redundant control devices,improving the reliability and reducing the mass of the antenna.The finite element method is used to establish a structural model for the satellite antenna,then a method is introduced to select proper diagonal cables and determine the corresponding forces.Numerical simulations of a simplified two-bay satellite antenna are first carried out to validate the proposed technique.Then,a simplified 18-bay antenna is also studied,because spaceborne satellite antennas have inevitably tended to be large in recent years.The numerical simulation results show that the proposed technique can be effectively used to adjust the static shape of planar phased-array satellite antennas,achieving high precision.

Design of an 868 MHz Printed S-Shape Monopole Antenna

The purpose of this work is to design and analyze an s-shaped printed circuit board (PCB) monopole antenna. The antenna was analyzed to operate at a resonance frequency band of 868 MHz;acceptable in 915 MHz as well. The s-shape is selected due to the need of reducing the overall size of the normal monopole antenna. The printed antenna was designed with an approximate overall size of 39 × 56 mm2 of which the antenna’s upper side is 26 × 39 mm2 while its reference ground board was sized at 39 × 30 mm2. The antenna is fed by a strip line of 3 × 1.5 mm2, in series with a 4.4 pF capacitance and shunt with an 8.7 nH inductance for purpose of antenna’s impedance matching with the input. A couple of existing publications showed that PCB antenna is not a new technology;however not an old technology for telecommunication industry. The raised problem by this work was duly solved with HFSS as a tool;excellent results are presented. After duly matching the antenna’s impedance with 50 Ω microstrip feed-line, solutions for overall performance were analyzed and demonstrated optimal: radiation patterns were proven omnidirectional, antenna gain optimized. The present antenna prototype’s overall dimensions can be readjusted according to any industrial and manufacturing requests.

Surface shape detection methods for large radio telescopes

The surface accuracy of a radio telescope is directly related to its operational efficiency and detection sensitivity.This is crucial under high-frequency observation conditions,where surface shape errors need to be controlled to within 1/16 of the working wavelength.In addition,the primary reflector of large radio telescopes is subject to dynamic deformation,caused by factors such as gravity and thermal effects.This paper presents a method for detecting the surface shape of radio telescopes using radio interferometry techniques combined with active reflector adjustment technology.This enables accurate assessment and correction of surface errors,ensuring the electrical performance of the radio telescope.This study investigates the practical applications of high-precision measurement techniques,such as microwave holography,out-of-focus holography,and wavefront distortion methods at the Tianma 65 m radio telescope(TMRT).Furthermore,the study presents the construction method of gravity models at different elevation angles and demonstrates the efficacy of the active reflector model.The results of the measurements indicate that the application of these methods to the TMRT has led to a notable enhancement of the accuracy of the primary reflector and a substantial improvement in efficiency in the Q-band.Through a process of iterative measurements and adjustments,the surface shape error is ultimately reduced to 0.28 mm root mean square(RMS).

B-spline surface fitting and simplified GO/PO analysis of subreflector correction for large Cassegrain antenna distortion compensation

The main surface of a large Cassegrain antenna consists of a large number of panels. There are inevitably random and systematic errors which will degrade the antenna pattern and limit its applicability when working at high frequencies. Correcting the subreflector surface is difficult to describe by a global expansion effectively with a small amount of data. This paper presents a simple and clear way for correcting the subreflector surface of a large Cassegrain antenna for achieving such compensation. The advantage of the method is that the geometrical optics （GO） analysis is extremely simplified by the concept of equivalent prime-focus paraboloid, and corrected deformations of the subreflector surface are determined by simple formulas which represent the relationship between distortions of the subreflector surface and phase of the main surface current. The final shape of the subreflector surface is represented by a B-spline surface. To obtain a satisfactory antenna pattern with the simplest subreflector surface, the optimal number of B-spline patches are searched by particle swarm optimization （PSO）. The shaping process is verified by compensating a 22-m Cassegrain antenna whose main reflector has 96 panels. The results are satisfactory and demonstrate the simplicity and effectiveness of the approach.

Finite Element Modeling and Design of Rectangular Patch Antenna with Different Feeding Techniques

The finite element modeling of three dimensional structures is important for researchers especially in the field of antennas and other domains of electromagnetic waves. This paper presents a finite element calculations and numerical analysis for the microstrip patch antennas. In this paper, two different designs have been modelled and analyzed and both designs are based on the rectangular patches. The feeding point of one design is inside the patch while the other design contains feeding point outside the patch is T shaped. The computational analysis showed some interesting results for radiation pattern and far field domain. For these designs, the characteristic impedance taken is 50 Ω and the operating frequency domain is 1.4 to 1.7 GHz. The microstrip patch antennas are encapsulated in the inert spherical atmosphere of 20 mm thickness containing air inside it.

Beam shaping with limited amplitude weight values for satellite active phased array antenna

To gain the tradeoff between lower sidelobe and higher power amplifiers efficiency,a transmitting beam shaping scheme with limited amplitude weight values for satellite active phased array antenna is presented. The scheme is implemented by a dual coding genetic algorithm(GA). Phase and amplitude of array weight vectors for beam shaping are encoded by real coding and finite length binary coding,respectively,which,maintaining accuracy of results,reduces the amplitude dynamic range and improves the efficiency of power amplifiers. The presented algorithm,compared with complex-coded GA,increases the convergence rate due to the search space's decrease. In order to overcome the prematurity and obtain better global optimization or quasi-global optimization,a new dual coding GA based on "species diversity retention" strategy and adaptive crossover and mutation probability are presented.

On the Design of Plus Slotted Fractal Antenna Array

A new technique which is a combination of fractal antenna and array antenna is presented to design Plus Slotted Fractal Antenna Array (PSFAA) in this paper. PSFAA with corporate feed operates at 2.5 GHz frequency. PSFAA is designed on FR4 substrate material with permittivity 4.4 and height 1.6 mm. PSFAA is designed up to 2nd iteration. High Frequency Structure Simulator (HFSS) software is used for simulation of PSFAA. The proposed antenna array operates at three bands with five frequencies 2.5 GHz, 4.1 GHz, 6.9 GHz, 7.4 GHz and 8.2 GHz. Simulated Return losses results of proposed PSFAA are -22.15 dB, -19.44 dB, -25.21 dB, -10 dB, -12.45 dB at above frequencies respectively. It has a gain of 9.22 dB at resonant frequency 2.5 GHz whereas conventional antenna array has a gain of 5.15 dB at resonant frequency 2.5 GHz. Return losses and gain of PSFAA also improved from conventional antenna array at various resonant frequencies.

Single-layer broadband planar antenna using ultrathin high-efficiency focusing metasurfaces

Phase gradient metasurfaces（PGMS） offer a fascinating ability to control the amplitude and phase of the electromagnetic（EM） waves on a subwavelength scale, resulting in new applications of designing novel microwave devices with improved performances. In this paper, a reflective symmetrical element, consisting of orthogonally I-shaped structures, has been demonstrated with an approximately parallel phase response from 15 GHz to 22 GHz, which results in an interesting wideband property. For practical design, a planar antenna is implemented by a well-optimized focusing metasurface and excited by a self-designed Vivaldi antenna at the focus. Numerical and experimental results coincide well. The planar antenna has a series of merits such as a wide 3-d B gain bandwidth of 15–22 GHz, an average gain enhancement of 16 d B, a comparable aperture efficiency of better than 45% at 18 GHz, and also a simple fabrication process. The proposed reflective metasurface opens up a new avenue to design wideband microwave devices.

New Traveling-Wave Antenna Resonating at 6 GHz Based on Artificial Transmission Line Metamaterial Structures for RF Portable Devices

Design of new metamaterial (MTM) traveling-wave antenna with “d-formed” left-handed structure is proposed. The proposed MTM structure is designed at a height of 0.8 mm from the ground plane with almost 2 GHz bandwidth. The most interesting feature of the design is the ability of enhancing the gain and total efficiency of the antenna without negative effects of the other important parameters like bandwidth. By using the “d-shaped” MTM structure and printed planar technique, the bandwidth of the MTM traveling-wave antenna is significantly increased at a resonant frequency of 6 GHz and also a foot print area reduction of the antenna structure is provided. Antenna size is 7.2 × 5 × 0.8 mm3. The proposed antenna is suitable for RF portable devices operating at 6 GHz.