Session 2P7 Antenna and Array: Theory and Design

8/14/2019 Session 2P7 Antenna and Array: Theory and Design

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Session 2P7

Antenna and Array: Theory and Design

A Class of Broadband Planar Traveling-wave Antennas and Their Latest Applications

Johnson Jenn-Hwa Wang, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Phase-only Synthesis of the Radiation Pattern of an Antenna Array with Quantized Phase Shifters

Alexander S. Kondratiev, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Stage-by-stage Testing Technique of Active Phased Array

M. V. Markosyan, Vahan H. Avetisyan, S. G. Eyremjyan, .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . 98

Experimental Investigations of Adaptive Reactance Parasitic Antenna Dipole Array

Maxim O. Shuralev, A. L. Umnov, A. Mainwaring, M. A. Sokolov, A. U. Eltsov, .. .. .. .. .. .. . .. .. 99

Planar Array Antenna with Parasitic Elements for Beam Steering Control

Mohd Tarmizi Ali, Tharek Abd Rahman, Muhammad Ramlee Bin Kamarudin, M. N. Md Tan, Ro-

nan Sauleau, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

Multiband MIMO Antenna with a Band Stop Matching Circuit for Next Generation Mobile Applications

Minseok Han, Jae-Hoon Choi, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Dual ISM Band Mircostrip Antenna for Satellite Internet Service

Byoungchul Kim, Sangwoon Lee, Joongyu Ryu, Hosung Choo, Hojin Lee, Ikmo Park, . . . . . . . . . . . . . 102

Directional GPS Antenna for Indoor Positioning Applications

Kerem Ozsoy, Ibrahim Tekin, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

Printed Dipole Array Fed with Parallel Stripline for Ku-band Applications

M. Dogan, Kerem Ozsoy, I brahim Tekin, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

A Circular Disc Monopole UWB Antenna Fed with a Tapered Microstrip Line on a Circular Ground

Yangjun Zhang, Masahiro Shimasaki, Toyokatsu Miyashita, .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 105

Improved Tapered Slot-line Antennas Loaded by Grating

Peng Zhang, Shu Jun Tand, Wen Xun Zhang, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107Using High Impedance Ground Plane for Improving Radiation in Monopole Antenna and Its Unusual

Reflection Phase Properties

Maryam Abootorabi, Mohsen Kaboli, Seyed Abdullah Mirtaheri, Mohammad Sadegh Abrishamian, . . 108

The Impact of New Feeder Arrangement on RDRA Radiation Characteristics

Ahmed S. Elkorany, A. A. Sharshar, S. M. Elhalafawy, .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 110

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94 Progress In Electromagnetics Research Symposium Abstracts, Moscow, Russia, August 1821, 2009

A Class of Broadband Planar Traveling-wave Antennas and Their

Latest Applications

Johnson J. H. Wang

Wang Electro-Opto Corporation (WEO), Marietta, Georgia 30067, USA

Abstract Classical antenna theory often ignores the practical problem of platform mounting,which can have deadly impact on antenna performance. This is an unavoidable problem since anantenna is invariably inseparable from a transceiver or platform, which the antenna is connectedwith or mounted on. In the worst scenario, the main radiator is the platform or transceiver, notthe antenna per se. The slot antenna and the microstrip patch antenna provide a narrowbandsolution to this problem. For broadband needs, a class of planar traveling-wave (TW) antennas,as depicted in Figure 1, and TW phased arrays employing such TW elements, emerged in thepast two decades [e.g., 1], offering a satisfactory solution. This paper addresses the fundamentaltheory for this class of planar TW antennas.

A common feature of these patented designs is a ground plane placed very close to a planarbroadband TW structure, which is preferably a self-complementary surface. The TW is charac-terized by a radial component of propagation to and from the geometrical center of the planar

TW structure. The conducting ground plane on the back side of the antenna enables the an-tenna to be conformally mounted on any platform, with minimal EMC/EMI problems as wellas a stable radiation property fairly independent of the mounting platform. In addition to anoctaval bandwidth of 10 : 1 or more, this class of broadband planar TW antenna offers featuressuch as dual-polarization and multifunction rarely available in other antennas.

Applications include ultra-wideband conformal body-wearable antennas, air/sea/ground vehi-cle antennas, handset antennas, planar phased arrays, etc. A recent application is in high-performance low-cost GNSS antennas that cover all three GNSS services (GPS/GLONASS/Galil-eo), requiring a wide frequency bandwidth of 1.1641.610GHz. The TW structure in this designis a planar four-arm spiral, which has an inherently stable phase center nearly independent ofspatial and frequency variations. Such a performance is not achievable by conventional GNSSantenna approaches such as the patch antenna and other broadband antennas. Its phase centerstability versus frequency and spatial angle is primarily limited by its manufacturing toleranceand the excitation accuracy of its feed network.

Outgoing wave

Ground planeMatchingnetwork

Reflected wave(from residual outgoing wave)

Side View

Top View

Radiation zone ( r~

for Mode-1)

0 r

Current densityr

zTW elementS

Feed

/ 2

Figure 1: The planar TW antenna.

REFERENCES

1. Wang, J. J. H., D. J. Triplett, and C. J. Stevens, Broadband/Multiband conformal circularbeam-steering array, IEEE Trans. Antennas and Prop., Vol. 54, No. 11, November 2006.


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Progress In Electromagnetics Research Symposium Abstracts, Moscow, Russia, August 1821, 2009 95

Phase-only Synthesis of the Radiation Pattern of an Antenna Array

with Quantized Phase Shifters

Alexander S. Kondratiev

Moscow Power Engineering Institute (Technical University), JSC Altair, Russia

Abstract At present, solution of many radar and communication problems requires applica-tion of antennas with shaped radiation patterns and/or pattern nulls or deep gaps in prescribeddirections. Antenna arrays, which have many controllable elements, are most suitable candidatesfor formation of such patterns. In many arrays, only the phases of the amplitude-phase distribu-tion over the array elements can be controlled. In this case, formation of an array pattern withprescribed properties requires solution of the so-called phase-only synthesis problem [1].

Phase-only synthesis problems are inherently nonlinear and, generally, are solved with the use ofnumerical methods [2, 3]. The most reliable methods are those based on reduction of the initialsynthesis problem to the problem of minimization of a nonlinear nonnegative definite function ofdesired phases and application of numerical optimization techniques to finding the minimum ofthis function. (In general, the minimum is local and the obtained solution is only approximate.)

In most cases, the element excitation phases are controlled with quantized phase shifters thatchange the excitation phases only stepwise. The value of phase increment is usually deter-mined from the formula

= 2/2K , (1)

where K is the number of binary digits.

In this case, it is desirable to solve the problem in the domain of discrete values of the desiredphases [2, 3]. This approach, in particular, allows formation of deep nulls in prescribed directions.

In formation of a shaped pattern, it is often desirable to ensure near uniform approximation ofthe desired shape. This approximation can be attained with the use of the Chebyshev metricor an approximation of this metric for the difference between the desired and the synthesizedpatterns.

Here, an approach to solution of the phase-only pattern synthesis problem is proposed thatinvolves

(i) formation of the objective function with the use of a power approximation of the Chebyshevmetric and

(ii) iterative minimization of this objective function by means of finite search over discrete phasevalues at each iteration.

A version of this approach is described below.

Let us specify the desired radiation pattern by its values at M angular directions F0m, m =1, . . . , M .

Then, the phase-only synthesis problem is reduced to solution of the following set of equations:

N

n=1

Fen (m, m) An exp(jn) exp(j (kxnxm + kynym + kznzm)) = F0

m,

m = 1, . . . , M , (2)

where Fen(m, m) is the radiation pattern of the nth array element in the mth angular direction(m, m) in the spherical coordinate system;

An and n are the amplitude and phase of the excitation of the nth array element;

kxn, kyn, and kzn are the Cartesian electric coordinates of the nth array element;

k = 2/ and is the wavelength.

Amplitudes An are fixed and system (2) is solved for desired phases n taking discrete valuesaccording to formula (1). Since the solution domain of this system of nonlinear equations is


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generally unknown, system (2) is solved approximately by reducing it to the objective function

Q =

M

m=1

Wm

N

n=1

Fen(m, m) An exp(jn)

exp(j(kxnxm + kynym + kznzm)) F0

m exp(jm)

l

, (3)

where m are the phase values whose values are specified during iterative minimization of thisobjective function [3] and l 2 is a positive even integer number.

The minima of objective function (3) are the approximate solutions to system (2).

Analysis of objective function (3) shows that, along each phase n, function (3) is periodicwith a period divisible by 2/l. This feature is used to develop a simple iterative minimizationtechnique in which objective function (3) is successively minimized along coordinates n. If l=2, the minimum along each coordinate can be found analytically [2, 3]. Ifl > 2, the minimum ateach iteration is found numerically by means of the search over a finite number of phase valuesdetermined by formula (1) within the period [0, 2]. The advantages of this synthesis procedureare the simplest selection of the search direction and a limited search interval at each iteration.

This procedure can be further improved by replacing the coordinatewise search method with

one of faster methods, for example, the well-known conjugate gradient method [4]. However,direct application of this method is impossible because phases n can take only discrete valuesdetermined by formula (1). If the phase values are considered continuous and formula (1) isapplied to the solution found with continuous phases, this operation may result in substantialdeterioration of the obtained solution, which is most pronounced for the null synthesis problems.

2

1

Figure 1: Initial and synthesized patterns for l = 2.

1 2

Figure 2: Initial and synthesized patterns for l = 4.


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To return the linear search performed at each iteration to the search over only the allowed phasevalues, one can use a technique in which the search direction is adjusted so that the componentsof the original search vector are approximated by the values that are the multiples of phaseincrement . A normalization procedure is used to set the maximum vector component to2. At each iteration, ob jective function (3) is simultaneously minimized along the coordinateschanged according to the above algorithm and the steps along coordinates n take only thediscrete values specified by formula (1). In practice, this is a stepwise approximation of theoriginal search direction.

An example of application of the coordinatewise version of the proposed method is shown belowfor the synthesis of a linear equispaced array of 50 isotropic radiators with a flat-top pattern. Thesynthesis results are shown in Figs. 1 and 2. In all figures, curves 1 correspond to the initial arraypattern and curves 2 correspond to the synthesized patterns for l = 2 (Fig. 1) and 4 (Fig. 2),respectively.

As seen from the results in Figs. 1 and 2, the synthesized patterns depend on power l. Changingthis parameter, it is possible to flatten the ripples on the top of the synthesized pattern.

REFERENCES

1. Cheng, D. K., Optimization techniques for antenna arrays, Proc. IEEE, Vol. 59, 16641674,1971.

2. Kondratyev, A. S., Method for phase synthesis of antenna arrays with additional require-

ments on the shape of the directivity pattern taken into account, Soviet J. CommunicationsTechnol. Electron., Vol. 36, 94102, 1991.3. Kondratyev, A. S. and A. D. Khzmalyan, Phase-only synthesis of antenna arrays for a given

amplitude radiation pattern, J. Communications Technol. Electron., Vol. 41, 859866, 1996.4. Fletcher, R. and C. M. Reeves, Function minimization by conjugate gradients, Computer J.,

Vol. 7, 149154, 1964.


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Stage-by-stage Testing Technique of Active Phased Array

M. V. Markosyan, V. H. Avetisyan, and S. G. EyremjyanYerevan Telecommunication Research Institute, Yerevan, Republic of Armenia

Abstract Manufacturing and bringing of the active phased array (APhA) to a readiness foroperation (with the goal of reception of the parameters inserted at the APhA designing) demandsignificant zeal and expenses. At production the step-by-step assembly of component units of theAPhA to entire antenna system is carried out. The basic element of APhA is transceiver module(TM), which combines the electronic-controlled discrete attenuator, phase-shifter, switches, poweramplifier and low-noise amplifier; N pieces of TM are combined in a cell; M pieces of cells arecombined in group; K pieces of groups are combined in subarray and F pieces of subarraies arecombined in entire system of the APhA. At assembling of new unit it is possible to disturb anoperability of one or more component units. On each stage of such sequential enlargements it isimportant to eliminate of faulty component units from process of following assembly for avoidingof additional expenditures.

With this goal in given article the technique of stage-by-stage testing and electric alignment ofthe APhA component units is offered at the described assembly process. In the beginning of

everyone specifically-observed stage the checking (according to the developed techniques) of thefinal assembly units of the previous stage is provided. Note, the final assembly units of the previ-ous stage are the component units of the specifically-observed stage unit, which should be tested.The mentioned checking of each final assembly unit of the previous stage is carried out in modeof in-phase and amplitude uniform excitations of its component units. The check testing definesoperability of the previous stage assembly units and also deviations of their amplitude and phasetransmission characteristics. On the basis of the received data about deviations for each of testedunits, the corrections by amplitude and phase are defined for inserting of additional attenuationsand phase-shifts, which necessary for their in-phase and amplitude uniform excitations in com-position of the observed stage assembly unit. Such excitation condition of the observed stagecomponent unit is final result of its electronic alignment. After that, the correctness of executedelectric alignment of the tested unit is checked by corresponding measurements and its certificateon required parameters is made out. It is an end of the specifically-observed stage.

Process of the TM testing is carried out on the basis of radiator far-field measurements by means of

the developed automatic measurement system, which determines also polarization characteristicsof its radiated wave. Testing of groups, subarraies and whole APhA is carried out by the offerednear-field automatic measurement system.

The offered stage-by-stage testing technique allows clearly and reliably to carry out a process ofbringing of the APhA to a readiness for operation in accordance with requirements on its electricparameters.


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Experimental Investigations of Adaptive Reactance Parasitic

Antenna Dipole Array

M. O. Shuralev1, 2, A. L. Umnov1, 2, A. Mainwaring3,M. A. Sokolov1, 2, and A. U. Eltsov1, 2

1Nizhny Novgorod State University, Nizhny Novgorod 603950, Russia2Intel Corporation, Nizhny Novgorod, Russia

3Intel Research Laboratory at Berkeley, CA 94704, USA

Abstract This work explores the theory and practice of low-cost beam steering antennasfor WiFi, specifically high-gain arrays of interest for long-distance point-to-point and point-to-multipoint links based on WiFi technology operating at 2.4 GHz. The antenna systems are con-structed on a basis of tunable impedance mirrors, named as reflectarrays, assembled from periodicarray of passive scatterers illuminated by a single, driven RF element, placed at 2.5 wave-lengthsfrom the center of the reflectarray. Although this approach avoids energy losses and unwantedinfluence between the passive elements through surface wave interactions, the close spacing ofthe elements leads to mutual coupling. This complicates the theoretical analysis and modeling

of these antennas, but these complications can be resolved through a combination of simulationand experiment. Four key aspects of this work are presented: (1) the careful balancing of theamplitude-phase characteristics of the passive scatteres with using special experimental schemes,taking into account most mutual coupling effect, (2) the development of multilayer structuresand array assemblies, intended for widening of phase range of the reflected RF radiation fromthe mirror, (3) an examination of the bandwidth, and (4) experimental measurement of antennadirectivity diagrams and pattern integrity. Our results demonstrated that highly directional pat-terns can be realized while controlling beam orientation in both azimuth and elevation. Prototypeantennas achieve 19 to 22 dBi of gain across an operational 120 degrees of azimuth and 20 degreesin elevation, using an array with an aperture of 100 cm 65 cm (5 rows of 100 elements each).


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Planar Array Antenna with Parasitic Elements for Beam Steering

Control

M. T. Ali1, T. A. Rahman2, M. R. Kamarudin2,M. N. Md Tan1, and R. Sauleau3

1Faculty of Electrical Engineering, Universiti Teknologi Mara (UiTM)Shah Alam, Selangor, Malaysia

2Wireless Communication Center (WCC), Universiti Teknologi Malaysia81310 UTM Skudai, Johor, Malaysia

3Institut delectronique et de telecommunications de Rennes, (IETR)UMR CNRS 6164, University of Rennes 1, France

Abstract A new antenna structure is formed by combining the concept of a reconfigurableplanar array antenna with the parasitic elements technique to improve the beam steering. Theintegration of PIN diode switches to the antenna has enabled to steer the antenna beams in thedesired direction. This can be done by changing the switches mode to either switch it ON orOFF. In this work, a number of reflectors have been proposed namely parasitic elements and

were placed between the patches which aimed to increase the steering beam angle. By havingsuch configuration, the main beam of the array can be titled due to the effect of mutual couplingbetween the driven elements and the parasitic elements (reflectors). The unique property of thisantenna design is that instead of fabricating all together in the same plane, the antennas feedingnetwork is separated from the antenna radiating elements (the patches) by an air gap distance.This will allow the interferences from the feeding line to be minimized. The optimization resultsfor the resonant frequencies of the antennas with variable air gap heights were also studied. Thecomparison results between antenna with and without parasitic elements were investigated in thispaper. The simulation results for the antenna will be compared with measurements, to show thatthe beam can be steered by controlling the switches mode. Experimental results are presentedto demonstrate the excellent performance of this antenna.


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Multiband MIMO Antenna with a Band Stop Matching Circuit for

Next Generation Mobile Applications

Min-Seok Han and Jaehoon Choi

Division of Electrical and Computer Engineering, Hanyang University

17 Haengdang-dong, Seongdong-gu, Seoul 133-791, Korea

Abstract Next generation mobile systems have to satisfy the requirements of high data ratesand flexible interfaces for different communication system standards. MIMO (Multiple InputMultiple Output) technology has been regarded as one of practical approaches to accommodatesuch requirements by increasing wireless channel capacity and reliability. However, it is usually abig challenge to place multiple antennas within a small and slim mobile handset while maintainingthe good isolation between antenna elements since the antennas are strongly coupled with eachother and even with the ground plane by sharing the surface currents distributed on it.

In this paper, a multiband MIMO antenna with a band stop matching circuit for next genera-tion mobile applications is proposed. The proposed multiband MIMO antenna consists of twodual-band PIFAs which provide wideband characteristics. In order to improve the isolation char-acteristic at the LTE band, a band stop matching circuit was inserted at the corner of each

antenna element. The inserted band stop matching circuit is to suppress the surface currentsat the specific frequency band and to generate two additional resonances in the 760 MHz bandto cover LTE operation and in the 860 MHz band to cover GSM850 operation. In addition,the band stop matching circuit reveals minimal effect on the upper band performance. Theproposed MIMO antenna can cover LTE, GSM850, GSM900, GSM1800, GSM1900, WCDMAand M-WiMAX services, simultaneously. Design considerations and experimental results of themultiband MIMO antenna with a band stop matching circuit are presented.

Figure 1: Geometry of the proposed multiband MIMO antenna.

without band stop matching circuit

Frequency [GHz]

0.0 0.5 1.0 1.5 2.0 2.5 3.0

S-parameters

-40

-30

-20

-10

0

LTE

698 ~ 800 MHz

GSM850/GSM900

824 ~ 960 MHz

GSM1800/GSM1900/WCDMA

1710 ~ 2170 MHz

M-WiMAX

2500 ~ 2690 MHz

S11

S21

VSWR 3:1

Isolation -10 dB

with band stop matching circuit

Frequency [GHz]

0.0 0.5 1.0 1.5 2.0 2.5 3.0

S-parameters

-40

-30

-20

-10

0

LTE

698 ~ 800 MHz

GSM850/GSM900

824 ~ 960 MHz

GSM1800/GSM1900/WCDMA

1710 ~ 2170 MHz

M-WiMAX

2500 ~ 2690 MHz

S11

S21

VSWR 3:1

Isolation -10 dB

Figure 2: Simulated S-parameter characteristics without and with band stop matching circuit.


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Dual ISM Band Mircostrip Antenna for Satellite Internet Service

Byoungchul Kim1, Sangwoon Lee1, Joongyu Ryu2,Hosung Choo3, Hojin Lee2, and Ikmo Park1

1Department of Electrical and Computer Engineering, Ajou University

5 Wonchun-dong, Youngtong-gu, Suwon 443-749, Korea2Broadcasting and Telecommunications Convergence Research Laboratory, ETRI161 Gajeong-dong, Yuseong-gu, Daejeon 305-700, Korea

3School of Electronics and Electrical Engineering, Hongik University72-1 Sangsu-dong, Mapo-gu, Seoul 121-791, Korea

Abstract In recent years, satellite internet has received much attention for wireless internetapplications on high-speed trains. The Korean high-speed train (KTX) network requires antennasthat operate at both the 2.4 GHz and 5.8 GHz industrial, scientific, and medical (ISM) bandsfor simultaneous transmission and receiving of data. Additionally, it should have nearly equalgain with similar radiation patterns in both bands for optimum communication. Microstrippatch antennas have been used in many applications due to their low cost, light weight, low

profile, and ease of fabrication. Dual-frequency operation can be obtained by making slots on themicrostrip patch, or by placing shorting pins at appropriate locations on the microstrip patch.However, when the higher frequency band is more than twice that of the lower frequency band,the radiation pattern of the higher resonant frequency becomes distorted due to the higher orderresonant modes. In this paper, a dual-band microstrip antenna with nearly equal gain and similarradiation patterns at the 2.4 GHz and 5.8 GHz ISM bands is described. The proposed antenna,shown in Fig. 1, has two Y-shaped slots on the microstrip patch. It is fabricated on an RO4003substrate, which has a dielectric constant of 3.38 and a thickness of 0.508 mm. The size of theantenna is 50 47.5 6.5 mm3, and it is fed by a coaxial cable. The measured bandwidth of theantenna is 2.3762.492 GHz and 5.4256.055 GHz for VSWR < 2. The measured gain is 8.37 dBand 8.38 dB for the 2.4 GHz and 5.8 GHz ISM bands, respectively.

Feed point

Patch with slots Ground plane

Figure 1: Antenna structure.


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Directional GPS Antenna for Indoor Positioning Applications

Kerem Ozsoy1, 2 and Ibrahim Tekin1

1Electronics Engineering, Sabanc University, Istanbul, Turkey2Vestek Electronic Research & Development Corp., Istanbul, Turkey

Abstract In this paper, a directional GPS antenna for L1 frequency 1575 MHz withRHCP and a high directive gain is proposed for indoor positioning applications. The proposedantenna is made of a standard off the shelf GPS patch antenna with an additional conical reflectorto enhance the gain and the beamwidth of the antenna. The angle of the cone reflector isoptimized by HFSS 11 software. Finally, the cone is fabricated, integrated with the patch antennaand measured. The measurement results show that the antenna with the reflector has a 9 dBigain and a beamwidth of 60 degrees with an axial ratio of 1 dB which agrees well with simulationresults.

Introduction: The Civil Global Positioning System (GPS) has become very popular in recentyears and it has wide usage in many areas. With the latest technological advances such asDifferential GPS (DGPS), Assisted GPS (AGPS), civil GPS receivers are able to locate themselves

with an error of 13 meters outdoors [1]. Although GPS is very successful in outdoor areas, it ishard to decode GPS signals indoors due to the additional signal loss caused by the buildings. Forindoors, signals go through additional loss of 1030dB [2], in which case, signal levels are too lowfor an off-the shelf GPS receiver to detect the satellite signal. In order to solve indoor coverageproblem, we plan to build an indoor positioning system that uses the GPS infrastructure. Thisindoor positioning system consists of GPS pseudo-satellites (pseudolite) and a GPS receiver withimproved positioning algorithms. A pseudolite should be able to pick up the satellite signal onlyfrom a given direction in the sky and transmit the amplified signals to an indoor area. Thereare several ways to design a directional antenna such as Yagi-Uda, horn, log periodic, reflectorand parabolic antenna or phased array systems [3]. Along these antennas, a reflector antennatype is chosen since these antennas are simple to manufacture, and also compact and robust inperformance and low cost.

In this paper, we propose a directional GPS antenna for L1 frequency 1575 MHz withRHCP and a high directive gain. A standard off the shelf GPS patch antenna is used in the

design, and directivity increase is achieved through the use of a conical reflector. Off-the-shelfmicrostrip patch antenna has a gain of 4 dBi. When the conical reflector is placed around the mi-crostrip antenna, gain of the microstrip antenna is increased while the beamwidth of the antennadecreases. The cone is optimized by running simulations on HFSS 11 software tool. Finally, thecone is fabricated and integrated with patch antenna and measured. The measurement resultsshow that the antenna has a 9 dBi gain which is 5 dB higher than the original patch antenna anda beamwidth of 60 degrees with an axial ratio of 1 dB. In the conference, design of the conicalreflector, the simulation results and the measurements obtained in an anechoic chamber will bepresented.

REFERENCES

1. Liu, H., H. Darabi, P. Banerjee, and J. Liu, Survey of wireless indoor positioning techniquesand systems, IEEE Transaction on Systems, Man, and Cybernetics, Vol. 37, No. 6, 10671077,November 2007.

2. Peterson, B. B., D. Bruckner, and S. Heye, Measuring GPS signals indoors, Proceedings ofthe Institute of Navigations ION GPS-2001, September 2001.

3. Balanis, C. A., Antenna Theory, Analysis and Design, 2nd ed., Wiley, New York, 1997.


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Printed Dipole Array Fed with Parallel Stripline for Ku-band

Applications

M. Dogan1, 3, K. Ozsoy1, 2, and I. Tekin1

1Electronics Engineering, Sabanci University, Istanbul, Turkey2Vestek Electronic Research & Development Corp., Istanbul, Turkey

3TUBITAK, UEKAE, Kocaeli, Turkey

Abstract This paper presents the design procedure of a printed dipole antenna and 1Darray configurations of the single dipole element in the Ku-Band with its metallic reflector planeparallel to the array plane. The proposed antenna has a natural beam tilt which is useful forsome specific applications. Several array configurations in 1D are simulated and tested. Theeffect of mutual coupling among each array elements is also investigated. Required modificationson the individual array element and the feed structures due to the effect of mutual coupling areexamined. The single dipole and array of dipole has measured VSWR values smaller than 2 inthe Ku-Band with simulated gains of 5.7 dBi and 12 dBi, respectively.

Introduction: Recent studies are highly focused on antenna design in Ku-Band. Since the

Ku-band has enough available bandwidth for satellite links, Ku-band systems are widely used insatellite communications, especially in the mobile antenna systems used in vehicles. There arealso other application areas of Ku-band systems such as weather radars and fire detection radars.These sort of systems needs highly directive antennas with a very wide frequency band covers theall Ku-Band to transmit signals to the receiver with equal power in the whole frequency rangeand an automatic tracking systems to capture the maximum power incident from the satellitewhile the time and place of the receiver changed. In order to provide good tracking system, onecan use digital phase shifter technology or mechanical systems to tilt the beam of the receiverboth in azimuth and elevation to the specified direction which will increase the cost of the systemor decrease the accuracy of the tracking system respectively. In this paper, a printed dipoleantenna which operates in the Ku-Band with high gain and tilted beam is proposed. Since theproposed antenna has a tilted beam in elevation, it will be used in mobile satellite communicationsystems to eliminate the mechanical or digital needs at least in one direction to tilt the beam ofthe system. Also, arrays of these printed dipoles will be investigated and the gain of the arrayswill be both simulated and measured.

Simulation & Measurement Results: The single printed dipole element designed in ADS-2006A has a VSWR < 2 in the 10.7 GHz13.1 GHz range. The measurement results show that ithas S11 < 10 dB in between 9 GHz14 GHz. The simulated gain of the single element printeddipole antenna is 5.7 dBi at 11.5 GHz. The characteristics of 1 2 printed dipole array is alsomeasured and the preliminary results show us that the array has VSWR < 2 in the Ku-band.

We have also simulated 1 8 dipole array in Ku band, and results show that the array returnloss is less than 10 dB in 10.712.7 GHz band. Simulated gain changes between 1012dBi inthe band of interest. The beam is tilted from the broadside direction such that only azimuthalrotation is necessary for a mobile antenna system. The measurement results and the simulatedresults of the single dipole element and 1 2 and 1 8 dipole arrays will be presented at theconference.


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A Circular Disc Monopole UWB Antenna Fed with a Tapered

Microstrip Line on a Circular Ground

Yangjun Zhang, Masahiro Shimasaki, and Toyokatsu MiyashitaDepartment of Electronics & Informatics, Ryukoku University

Seta, Ohtsu 520-2194, Japan

Abstract The printed disc monopole antenna is considered a good candidate for 3.1 to10.6 GHz UWB systems [1, 2]. This paper presents a miniature circular disc monopole UWBantenna implemented on a FR-4 substrate (r = 4.4). The antenna was miniaturized by using atapered microstrip feed line on a circular ground, as shown in Fig. 1. The total size of antenna is4030mm2, and the diameter of radiation disc is 12 mm. The results of measured and simulatedreturn loss are shown in Fig. 2. It indicates there are differences between the simulated andmeasured return loss, but both the simulated and measured results show that good impedancematching has been obtained as the 10 dB return loss bandwidth covers the whole UWB bandfrom 3.1 to 10.6 GHz.

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Figure 1: The UWB antenna configuration.

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Figure 2: Measured and simulated returnloss.

The radiation patterns of the proposed antenna over the UWB frequency band have been mea-sured. The results at 8 GHz are shown in Fig. 3. It is noticed that the measured and simulatedradiation patterns agree well, and the omnidirectional pattern was shown at x-y-plane. Thetime-domain performance of the UWB antenna is shown in Fig. 4, where the group delay of thetwo UWB antennas placed with a distance of 36 cm was given. Within the frequency range from3 to 9 GHz, the group delay is about 2 ns.

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Figure 4: Measured group delay.


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REFERENCES

1. Cho, Y. J., K. H. Kim, D. H. Choi, S. S. Lee, and S.-O. Park, A miniature UWB planarmonopole antenna with 5-GHz band-rejection filter and the time-domain characteristics, IEEETrans. on Antennas and Propagation, Vol. 54, No. 5, 14531460, 2006.

2. Guo, L., J. Liang, C. C. Chiau, X. Chen, C. G. Parini, and J. Yu, Performances of ultra-wideband disc monopoles in time domain, IET Microwave Antennas Propag., Vol. 1, No. 4,955959, 2007.


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Improved Tapered Slot-line Antennas Loaded by Grating

Peng Zhang, Shu Jun Tang, and Wen-Xun ZhangState Key Laboratory of Millimeter Waves, Southeast University

Nanjing, Jiangsu 210096, China

Abstract The tapered slot-line antenna (TSA) has been used widely as element of phasedarrays, feed of reflector or reflectarray, UWB radiator for time-domain systems. It is a travelling-wave end-fire antenna with advantages of wideband, uni-directive beam, and thin-sheet structure.However, its gain is less than a broadside antenna with the similar sizes; the cost of enhancinggain will be sharply extending its length; the bandwidth depends on the taper ratio (max./min.of the slot-width) and the length of taper too. Hence, a risen question is how to further improvethe performance of Gain or Bandwidth based on a fixed structural frame? The answer should beto utilize sufficiently the frame-space, one scheme is just setting proper grating inside the zoneof tapered slot. Correspondingly, two kinds of samples are designed, simulated, and tested withgood results as expected.

One is a gain enhanced TSA with grating load and symmetric linear taper. It increases gain 2 dBup over the frequency range of 6.0 9.5 GHz (45.2%); or 3 dB up over 8.0 9.5 GHz (17.1%).

However, the bandwidth for VSWR 2.0 : 1 was slightly decreased from 5.7 11.2 GHz (65.1%)to 5.3 9.6 GHz (57.7%). In addition, the beam-width in E- and H-planes approaches to thesame.

Another is a bandwidth broaden TSA with grating load and asymmetric exponential (Vivaldi) ta-per. It expands the bandwidth 2.0 6.0GHz for VSWR 2.0 : 1, and also 3.0 6.0 GHz (75%)for vertical shaping pattern satisfying the specifications of base-station in mobile communicationsystem. Especially, the VSWR 1.5 : 1 is over both two WiMAX bands of 3 .3 3.8GHz and5.1 5.8 GHz; while the service coverage efficiencies are higher than 69.5% and 73.2% respec-tively; about 1 dB gain enhancement, and also improved radiation patterns with lower back-lobeand downward null-filling are achieved.

Both samples keep planar structure with complete printed technology in fabrication, and maintainthe frame sizes.

ACKNOWLEDGMENTThis work was supported by the National High-Tech Project (No. 2007AA01Z264).


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Using High Impedance Ground Plane for Improving Radiation in

Monopole Antenna and Its Unusual Reflection Phase Properties

S. M. Abootorabi, M. Kaboli, S. A. Mirtaheri, and M. S. AbrishamianK. N. Toosi University of Technology, Iran

Abstract In this paper improving radiation characteristics of monopole antenna on a highimpedance ground plane has been investigated. For this purpose the properties of periodicelectromagnetic band gap (EBG) structures have been used [1, 2].

As we know conductors are used as reflectors or ground plane in many antenna situations. Surfacewaves or surface currents are bound to the interface of metal and air. Recent researches have dealtwith the suppression of surface wave to improve radiation characteristics of monopole antenna

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Figure 1: Comparison of radiation patterns on EBG ground plane and normal ground plane using HFSSsimulation.

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Figure 2: Comparison of measurement and HFSS simulation, (a) EBG ground plane, (b) Normal metalground plane.


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using high impedance ground plane (HIGP) in high frequencies such as 35 GHz with hexagonalpatches on substrate [3, 4]. In this study high Impedance surface (HIS) as ground plane formonopole antenna at lower frequencies such as 6 GHz with square patches in shape have beenused. Due to suppression of surface waves in the band gap, a significant amount of power thatis wasted in back lobes reduces about 8 dB, also radiation power in forward direction increasesabout 10 25 dB in some directions. Comparison of patterns on normal metal ground planeand HIGP which are obtained by HFSS simulation could be seen in Figure 1. There are goodagreements with measurement and simulation results as shown in Figure 2, in 6 GHz frequency.

Effect of the ground plane dimension and number of square patches have also been investigatedand it has been observed that a bigger ground plane and more number of metal patches will havea better effect of improving radiation pattern.

Another property that is confined to EBG structures is their unusual reflection phase which ischanging continuously from +180 to 180 [5]. We changed the length of monopole antenna from0.245 to 0.27 and it found that where the monopole antenna has a good return loss is veryclose to points that the reflection phase has a quantity between 90 45.

Consequently this HIS may be very useful in a variety of electromagnetic problems and antennastructures.

REFERENCES

1. Xu, H.-J., Y.-H. Zhang, and Y. Fan, Analysis of the connector section between K connector

and microstrip with Electromagnetic Band Gap (EBG) structure, Progress In ElectromagneticResearch, PIER 73, 239247, 2007.2. Pirhadi, A. and M. Hakkak, Using electromagnetic band gap superstrate to enhance the

bandwidth of probe-fed microstrip antenna, Progress In Electromagnetic Research, PIER 61,215230, 2006.

3. Sievenpiper, D., L. Zhang, R. F. Jimenez Broas, N. G. Alexopolous, and E. Yablonovitch,High-impedance electromagnetic surfaces with a forbidden frequency band, IEEE Transac-tions on Microwave Theory and Technique, Vol. 47, No. 11, November 1999.

4. Sievenpiper, D., High-impedance electromagnetic surfaces, PhD Dissertation, UCLA, 1999.5. Yang, F. and Y. Rahmat Samii, Microstrip antennas integrated with Electromagnetic Band-

Gap (EBG) structures: A low mutual coupling design for array applications, IEEE Transac-tions on Antennas and Propagation, Vol. 51, No. 10, October 2003.


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The Impact of New Feeder Arrangement on RDRA Radiation

Characteristics

A. S. Elkorany, A. A. Sharshar, and S. M. ElhalafawyDepartment of Electronics and Electrical Comm., Faculty of Electronics Eng.

Menoufia University, Menouf, Menoufia 32952, Egypt

Abstract Dielectric resonator antennas (DRAs) have been extensively investigated after thefirst paper published by Long et al.. Recently one of the major topics in DRA research is toenhance the impedance bandwidth. The techniques that have been used to widen the impedancebandwidth include, inserting air gap between the dielectric and the ground plane, using differ-ent dielectric geometries, using strip fed, using hybrid configuration, and using multi-segmentconfiguration.

Rectangular dielectric resonator antenna RDRA with an air gap that inserted between the dielec-tric and ground plane was previously proposed, and an achievement in the impedance bandwidthin the order of 31% between 4.5 GHz and 6.2 GHz has been obtained. In this work, a furtherdevelopment in the antenna structure has been suggested to get further improvement in the an-tenna impedance bandwidth. A new feeder arrangement has been proposed and its effect on theimpedance bandwidth has been recorded. This is done by inserting a small rectangular metallicpatch within the air gap between the ground plane and the dielectric. The metallic batch is con-nected to the inner of the coaxial probe feeder. This technique was used successfully in a previouswork with microstrip patch antenna, in which two metallic patches with different shapes wereinserted between the patch and ground plane. In the present research the dimensions of insertedpatch have been changed and the impact of that on the impedance bandwidth has been examined.The dielectric that is used is FR4 with r = 4.5, and its dimensions is 20 mm 12mm 5mm,the probe diameter is 1.25 mm, and its height is 2.5 mm, the inserted patch height is 1 mm, alltheses parameters are held constant in all cases. Unexpected ultrawide impedance bandwidthhas been obtained. Some results are recorded here to show the effect of this new feeder on theantenna impedance bandwidth. An impedance bandwidth of about 2.55 : 1 between 10.2 GHzand 26 GHz is achieved when the patch dimensions were 9 mm 4 mm, while the bandwidthextends from 16 GHz up to a value behind 34 GHz is achieved when the patch dimensions was

16mm

3 mm. The maximum radiation is in the broadside direction and is obtained with asuitable cross polarization level.

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Session 2P7 Antenna and Array: Theory and Design

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