Therefore, to include the WiMAX band in operation, we inserta pair of symmetrical meandered return patches (section 3) be-tween section 2 and section 1. With section 3 added, the upper endoperating limit at VSWR � 2.5 for the upper band was found toincrease to 2859 MHz as depicted in Figure 2 (a 10% increment inbandwidth). Furthermore, an improvement in impedance matchingfor both lower and upper resonant bands is also observed. For thiscase, the wide upper band centred at 2214 MHz for the proposedantenna has an impedance bandwidth of 1289 MHz (58.22%)measured from 1570 to 2859 MHz. Its band 1 centred at 970 MHzis with impedance bandwidth of 200 MHz (20.62%), slightlysmaller than prototype B antenna. The detailed measurements forall the three mentioned antennas are presented in Table 1.

Figures 4–10 present the measured radiation characteristics ofthe proposed antenna at three principal planes at the frequencies of925, 1575, 1795, 1920, 2170, 2450, and 2600 MHz. Their respec-tive peak gains for this case are 2.572, 0.6, �1.384, �1.124, 0.037,1.031, and 2.243 dBi, respectively. Because the radiation patternsfor each operating band measured from 1795 to 2600 MHz aregenerally similar, it indicates that stable radiation patterns areachieved over the upper band, whereby this behaviour is contrib-uted mainly by the quarter-wavelength resonant modes drivenalong sections 1 and 2 (without considering the horizontal sectionof the inverted L), and sections 1 and 3. As for the lower band, anear-omni-directional pattern is also observed at its x-y plane. Notethat the radiation patterns for GLONASS and MSS are very muchsimilar to the 1575 MHz GPS pattern, and hence are not presented.

The measured peak gain variation for all the operating bands(across VSWR 2.5:1) of the proposed antenna are depicted inFigure 11. Except for UMTS and WiMAX band which demon-strated a gain variation of around 1.16 and 0.99 dB, respectivelyacross its operating bands, stable gain variation much lower than 1dB for other operating bands are demonstrated.

4. CONCLUSION

A multiband planar antenna designed for telecommunication ser-vices such as for GSM/MSS/PCS/DCS/UMTS operations, naviga-tion systems such as GPS/GLONASS, and internet services suchas WiBro/WLAN operations has been proposed and experimen-tally investigated. By simply inserting a pair of meandered returnpatch line to the antenna, wide impedance bandwidth of around58% was realized in the upper band. Good impedance matchingwas also achieved with the lower band demonstrating an imped-ance bandwidth of around 20%. Furthermore, stable radiationcharacteristics and gain variation were also obtained.

REFERENCES

1. K.L. Wong, G.Y. Lee, and T.W. Chiou, A low-profile planar monopoleantenna for multiband operation of mobile handsets, IEEE Trans An-tennas Propag 51 (2003), 121–125.

2. J.W. Wu, C.R. Lin, and J.H. Lu, A planar meander-line antenna fortriple-band operation of mobile handsets, Microwave Opt Technol Lett41 (2004), 380–386.

3. X. Jin, Z.W. Du, and K. Gong, A compact multiband planar antenna formobile handsets, IEEE Trans Antennas Propag Lett 5 (2006), 343–345.

4. Z.W. Du, K. Gong, and J.S. Fu, A novel compact wide-band planarantenna for mobile handsets, IEEE Trans Antennas Propag 54 (2006),613–619.

5. C.A. Shen and K.H. Lin, A broadband internal planar monopole antennafor mobile phone, Microwave Opt Technol Lett 48 (2006), 768–769.

6. Y.W. Chi and K.L. Wong, Internal compact dual-band printed loopantenna for mobile phone application, IEEE Trans Antennas Propag 55(2007), 1457–1462.

7. K.L. Wong, Y.W. Chi, and S.Y. Tu, Internal multiband printed folded

slot antenna for mobile phone application, Microwave Opt Technol Lett49 (2007), 1833–1837.

8. C.Y.D. Sim, Multiband planar antenna design for mobile handset,Microwave Opt Technol Lett 50 (2008), 1543–1545.

© 2009 Wiley Periodicals, Inc.

BALANCED AND SINGLE-ENDEDHANDSET ANTENNAS: FREE SPACEAND HUMAN LOADING COMPARISON

Juan Jose Arenas,1 Jaume Anguera,1,2 and Carles Puente1,3

1 Technology and IPR Department, Fractus, Barcelona, Spain;Corresponding author: jaume.anguera@fractus.com2 Electronics and Communications Department, Universitat RamonLLull, Barcelona, Spain3 Theory and Signal Communications Department, UniversitatPolitecnica de Catalunya, Barcelona, Spain

Received 15 December 2008

ABSTRACT: A study of the electromagnetic properties of balanced andsingle-ended handset/wireless antennas in free space and human bodyscenario is presented. The article compares two particular cases, a sin-gle monopole and a balanced dipole, in terms of return loss, efficiency,and radiation pattern when changing the ground plane size. The sameexperiment is carried out taking into account a holding scenario, that is,when a phantom hand is holding the ground plane. © 2009 Wiley Peri-odicals, Inc. Microwave Opt Technol Lett 51: 2248–2254, 2009;Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.24525

Key words: handset antennas; balanced antennas; human body

1. INTRODUCTION

Balanced antennas have been shown to be more independent of theground plane than single-ended antennas [1–3]. This behaviorcould be used to design handset/wireless antennas that can beincluded in several devices with a lower engineering/designingeffort than a single-ended antenna which is more dependent of theplatform.

If the balanced antenna is more independent of the groundplane, it seems natural that if the ground plane conditions arechanged, the radiation characteristics of the antenna would be lessaffected. For example, the interaction of a human hand with ahandset/wireless device having an embedded antenna is a scenariowhere the ground plane conditions are modified.

A study of the behavior of a single-ended and balanced antennais presented in free space and with the presence of a human hand[4–7].

The article is divided as follows. In section 1, a free spaceanalysis is presented. The section includes a comparison betweena single-ended (monopole) antenna and a balanced (dipole) an-tenna when their ground plane lengths are modified. Results ofVSWR, radiation patterns and current intensity are shown. Insection 2, single-ended and balanced antenna with human handinteraction are compared. Finally, conclusions are presented

2. FREE SPACE ANALYSIS

To study the dependence of the ground plane between balancedand single-ended antennas, some simulations and measurementsare shown, in this case in a free space environment. IE3D v12electromagnetic software was used to run the simulations. Twodifferent ground plane lengths are defined, 0.5 � and � at f � 2.4

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GHz. A balanced antenna (dipole) and a single-ended antenna(monopole) are designed to obtain VSWR �2.5 at 2.4 GHz (Zo �50 �). The antenna dimensions are: 29 mm (arm length) for themonopole and is 29 � 2 � 58 mm (arms length) � 1 mm (distancebetween arms) � 59 mm for the dipole (see Fig. 1).

It is shown that the impedance of the balanced antenna isindependent of the length of the ground plane (see Fig. 2). Thesingle-ended antenna is completely dependent of the ground planelength, but the bandwidth achieved with this kind of antenna islarger than the one obtained with the balanced antenna. In thiscase, considering a VSWR �2.5, the monopole bandwidth for a0.5 � ground plane length is 17.3% and with a � ground plane is23.7%; for the dipole is 12.5% for both cases.

To better understand why the balanced antenna is more inde-pendent of the ground plane than the single-ended antenna, a studyof the current intensity for all the cases is shown in Figs. 3 and 4.Figures 3 and 4 are represented with a maximum value of electriccurrent of 15 A/m and the maximum value for each figure isnormalized to the same value to compare both cases. In case a) andb) of Figure 3, the 0.5 � ground plane length is simulated with themonopole and dipole antenna. It is shown that in the balanced case(a), the currents on the ground plane taking into account the largeedges are equal in magnitude but opposite in phase. Therefore,

these currents have a cancellation effect and the ground plane isnot helping the antenna to radiate. This mode is a nonradiatingmode, called a transmission line mode [8].

For the single-ended antenna case, these currents on the groundplane are not cancelled, and therefore, the groundplane is aneffective radiator. This mode is called radiating mode. For single-ended antennas, the radiation mode due to the groundplane en-hances the bandwidth when the groundplane is properly designed[9–13].

The same behavior can be observed if the � ground planelength is analyzed (see Fig. 4). The case “c” and “d” represent thebalanced antenna (dipole) and the single-ended antenna (mono-pole), respectively. For this particular case, a higher order mode issupported.

Based on these simulations results, it is clearly demonstratedthat the groundplane affects the single-ended performance. For thisparticular case, the bandwidth is larger than the balanced case.Moreover, based on the current distribution, the radiation patternshould be determined not only by the antenna but also by thegroundplane. This hypothesis is analyzed next.

Figure 1 IE3D designs for the monopole (a) and the dipole antenna (b).[Color figure can be viewed in the online issue, which is available atwww.interscience.wiley.com]

Figure 2 Simulated VSWR of balanced antenna and single-ended an-tenna depending of the ground plane length. [Color figure can be viewed inthe online issue, which is available at www.interscience.wiley.com]

Figure 3 Current vectors for the balanced antenna (a) and single-endedantenna (b) with a 0.5 � ground plane length at 2.44 GHz. [Color figure canbe viewed in the online issue, which is available at www.interscience.wiley.com]

Figure 4 Current vectors for the balanced antenna (a) and single-endedantenna (b) with a � ground plane length at 2.44 GHz. [Color figure can beviewed in the online issue, which is available at www.interscience.wiley.com]

DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 9, September 2009 2249

If the ground plane does not interact with the antenna in thecase of balanced antennas, it seems natural that if the radiatingelement is not changed, its radiation pattern will be constant whenchanging the ground plane size. To check this hypothesis, thesimulation models shown in Figure 1 are manufactured in thelaboratory to measure the radiation patterns. As in the simulation,the antenna and the ground plane are printed on a FR4 substrate.To access the antenna feeding, a microcoaxial cable is attached tothe ground plane. To feed the dipole, a balun is used (MurataLDB182G4510C-110). Measurements are performed in a SatimoStargate SG32 at Fractus laboratory.

Analyzing the radiation patterns for the single-ended antenna andbalanced antenna for 0.5 � and � ground plane length, it can beobserved that the radiation pattern for the single-ended antennachanges when the length of the ground plane is modified (see Fig. 5).On the contrary, the balanced antenna has approximately a radiationpattern independent of the length of the ground plane (see Fig. 6).

To have a figure of merit that indicates how similar the radiationpatterns are, the correlation coefficient is calculated. For each cut (�� 0°, � � 90°, and � � 90°), the correlation between radiationpatterns for each ground plane length is calculated as follows:

� �cov�x, y�

�x�y(1)

where x � Etotal(�) for the 0.5 � PCB length and y � Etotal(�) forthe � PCB length, �x and �y are the standard deviation for x andy, respectively.

The results for the correlation coefficient are shown in Table1. The pattern cuts of the balanced antenna (dipole) whenchanging the groundplane size are more similar (high correla-tion) than the single-ended (monopole) antenna pattern cuts(lower correlation). Moreover, the radiation pattern for thesingle-ended antenna is a combination of the radiation given bythe antenna and the ground plane. For the balanced antenna, theradiation pattern is that given for the antenna independentlyfrom the ground plane.

Up to this point, we can conclude than in a free-spacescenario and taking into account the ground plane sizes, thesingle-ended antenna presents more bandwidth than the bal-anced one. Based on radiation pattern data, it seems that thebalanced antenna is more independent of the ground plane.Therefore, any change or modification on the ground planeshould have to have more impact on the single-ended antenna.Next section deals with this.

3. HUMAN INTERACTION ANALYSIS

The objective of this section is to analyze a particular case ofgroundplane modification which is the hand loading effect. Theexperiment consists on loading the ground plane with a phantomhand and compare bandwidth and efficiency for the two cases, thesingle-ended and the balanced one. This example is of particularinterest since it may be an example of a user holding a wireless/handset device.

Figure 5 Single-ended antenna radiation pattern cuts for 0.5 � and � ground plane length (Etotal). [Color figure can be viewed in the online issue, whichis available at www.interscience.wiley.com]

2250 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 9, September 2009 DOI 10.1002/mop

In these cases, when the holding the device, the user is per-turbing the ground plane of the device. In the case of a single-ended antenna, this effect is expected to have more impact than inthe balanced case. This is analyzed next.

A study on how a human hand affects the behavior of theantennas is performed using the balanced and single-ended an-tenna with a � ground plane length.

To simulate the effect of a human hand, a basic model in IE3Dis designed (see Fig. 7). A parallelepiped with 55 mm � 85 mm �62 mm dimensions simulates the human hand. It is defined in IE3Das a dielectric with a permittivity of �r � 50 and a loss tangent of0.26 at 2.5 GHz to simulate the electrical properties of a real hand

Figure 6 Balanced antenna radiation pattern cuts for 0.5 � and � ground plane length (Etotal). [Color figure can be viewed in the online issue, which isavailable at www.interscience.wiley.com]

TABLE 1 Correlation Coefficient for � � 0°, � � 90°, and� � 90° Cuts for the Balanced Antenna and Single- EndedAntenna

Correlation Coefficient

� � 0° cut � � 90° cut � � 90° cut

Balanced antenna 0.95 0.96 0.88Single-ended antenna 0.38 0.41 0.43

Figure 7 Human hand basic model dimensions, three-dimensional view of the design in IE3D and real photo of the experiment. [Color figure can be viewedin the online issue, which is available at www.interscience.wiley.com]

DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 9, September 2009 2251

[14]. The experiment consists of computing the return loss andradiation efficiency as a function of the distance (d, see Fig. 7)between the hand and the antenna.

The radiation efficiency (r) is compared in both cases (bal-anced and unbalanced antenna). Radiation efficiency is defined asthe relation between the antenna radiated power and the powerdelivered to the antenna in a perfect match situation:

r �Rr

Rr R�

where Rr is the radiation resistance and R� is the ohmic lossesIn both cases (Figs. 8 and 9), as the hand is moving near the

antenna, the radiation efficiency of the antenna is lower than in thecase where the hand is placed away from the antenna. This is anexpected behavior because the hand is introducing losses and thusreducing the radiation efficiency. For the central frequency ofoperation (in this case 2.4 GHz), in the balanced case (see Fig. 8)the radiation efficiency is slightly larger than in the single-ended

case (see Fig. 9). The exact values are shown in Table 2. Thedifference between cases is 1 dB approximately.

In a real device, the power transmitted by the antenna is relatedto the radiation efficiency but modified by the matching of theantenna to the power source. This parameter is called total antennaefficiency (a) and is the relationship between the antenna radiatedpower and the total input power to the antenna. It can be definedas,

a � r�1 � �S11�2� (2)

where r is the radiation efficiency and S11 is the input reflectioncoefficient of the antenna.

In Figures 10 and 11, the total antenna efficiency for the dipoleand the monopole is represented. For the central frequency ofoperation (in this case 2.4 GHz), the value of the antenna effi-ciency for the balanced antenna is not always higher than thesingle-ended antenna as in the case of the radiation efficiency. Inthis case, for some distances between the hand and the antenna, thebalanced antenna presents better antenna efficiency and for someother distances, the radiation efficiency of the single-ended an-tenna is higher. The exact values can be found in Table 3.

To better understand why the total antenna efficiency is inaverage the same, VSWR is also computed. In Figures 12 and 13,the VSWR of the balanced (dipole) and single-ended (monopole)

Figure 8 Radiation efficiency of the balanced antenna depending of thedistance (d, see Fig. 7) between the antenna and the simulated hand. [Colorfigure can be viewed in the online issue, which is available at www.interscience.wiley.com]

Figure 9 Radiation efficiency of the single-ended antenna depending ofthe distance (d, see Fig. 7) between the antenna and the simulated hand.[Color figure can be viewed in the online issue, which is available atwww.interscience.wiley.com]

TABLE 2 Radiation Efficiency for the Balanced and Single-Ended Antenna Depending of the Distance Between theAntenna and the Simulated Band

Radiation Efficiency at 2.4 GHz

Distance (mm) Single-Ended Antenna Balanced Antenna (dB)

1 6.8% 8.6% 1.045 22.8% 25.7% 0.5310 38.9% 45.0% 0.6320 54.9% 73.5% 1.2740 66.7% 87.8% 1.19100 80.2% 93.4% 0.66

is defined as the difference between the balanced antenna and single-ended antenna [balanced antenna (dB) � single-ended antenna (dB)].

Figure 10 Antenna efficiency of the balanced antenna depending of thedistance between the antenna and the simulated hand. [Color figure can beviewed in the online issue, which is available at www.interscience.wiley.com]

2252 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 9, September 2009 DOI 10.1002/mop

antenna is represented. In the balanced (dipole) antenna case, thefrequency shift of the antenna matching due to the hand effect (seeFig. 11) is not larger as in the case of the single-ended (monopole)antenna. For the balanced antenna, the maximum variation infrequency is 12 MHz (5.1%), and for the single-ended antenna is400 MHz (16.3%). This variation is calculated with the lowerVSWR value for each distance.

As in the free space analysis, the balanced (dipole) antenna isless sensitive to perturbations of the ground plane, in this caseproduced by the human hand. In the other hand, the bandwidth ofthe single-ended (monopole) antenna is larger than the balancedantenna, for typical VSWR �3. In this case, the ground plane ishelping to radiate the single-ended antenna generating a radiatingelement larger than the balanced antenna, and then, producing alarger bandwidth.

4. CONCLUSIONS

A comparison between single-ended (monopole) antenna andbalanced (dipole) antenna is presented in two scenarios, a freespace and a dielectric with losses interaction scenario (humanhand) for a particular frequency range of operation (2.4 GHzband). In both cases, the balanced antenna has more stableradiation properties. It is independent of the ground planelength in terms of VSWR or radiation pattern. Its behavior is

more constant than a single-ended antenna when the humanhand interacts with the ground plane.

The single-ended antenna depends more on the ground planethan the balanced antenna. Any variation in the ground planeaffects on the radiation properties of the antenna, varying itsVSWR or radiation pattern. When the human hand interactswith its ground plane, the VSWR is modified. However thebandwidth of the single-ended antenna is larger than the bal-anced case (with a � ground plane, 12.5% for the balancedantenna and 23.7% for the single-ended antenna, almost thedouble).

The total antenna efficiency in a human hand scenario for bothantenna types (single-ended and balanced) is almost the same. Inthis scenario no clear advantage is shown if it is used a balancedantenna instead of a single-ended antenna. In addition, the spaceoccupied by the single-ended antenna is two times less than thebalanced antenna which it is a significant advantage for wireless/handset devices.

Figure 11 Antenna efficiency of the single-ended antenna depending ofthe distance between the antenna and the simulated hand. [Color figure canbe viewed in the online issue, which is available at www.interscience.wiley.com]

TABLE 3 Antenna Efficiency for the Balanced and Single-Ended Antenna Depending of the Distance Between theAntenna and the Simulated Band

Antenna efficiency at 2.4 GHz

Distance (mm) Single-Ended Antenna Balanced Antenna (dB)

1 4.1% 4.6% 0.475 13.2% 11.8% �0.4910 26.9% 22.7% �0.7520 49.5% 46.8% �0.2440 54.1% 75.9% 1.47100 68.8% 75.3% 0.39

is defined as the difference between the balanced antenna and single-ended antenna [balanced antenna (dB) single-ended antenna (dB)]

Figure 12 VSWR of the balanced antenna depending of the distancebetween the antenna and the simulated hand. [Color figure can be viewedin the online issue, which is available at www.interscience.wiley.com]

Figure 13 VSWR of the single-ended antenna depending of the distancebetween the antenna and the simulated hand. [Color figure can be viewedin the online issue, which is available at www.interscience.wiley.com]

DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 9, September 2009 2253

REFERENCES

1. S. Hayashida, H. Morishita, and K. Fujimoto, Self-balanced widebandfolded loop antenna, IEE Proc Microwave Antennas Propag 153(2006), 7.

2. B.S. Collins, S.P. Kingsley, J.M. Ide, S.A. Saario, R.W. Schlub,and S.G. O’Keefe, A multi-band hybrid balanced antenna, IEEEInternational workshop on antenna technology: Small antennasand novel metamaterials, White Plains, New York, March 6 – 8,(2006).

3. R.A. Abd-Alhameed, P.S. Excell, K. Khalil, R. Alias, and J. Mustafa,SAR and radiation performance of balanced and un-balanced mobileantennas using a hybrid computational electromagnetics formulation,IEE Proc Sci Meas Technol 151 (2004), 440–444.

4. J.J. Arenas, Analysis and design of balanced antennas for wirelessdevices (in Spanish), Master thesis, Telecommunication Engineer-ing, University Polytechnic of Catalunya (UPC), Barcelona, Spain,(2008).

5. H. Morishita, H. Furuuchi, and K. Fujimoto, Characteristics of abalance-fed loop antenna system for handsets in the vicinity of humanhead or hand, IEEE Antennas and Propagation Society InternationalSymposium, Salt Lake City, USA, July 2000.

6. J. Toftgård, S.N. Hornsleth, and J.B. Andersen, Effects on portableantennas of the presence of a person, IEEE Trans Antenn Propag 41(1993), 739–746.

7. K. Sato, K. Nishikawa, N. Suzuki, and A. Ogawa, Analysis of antennasmounted on portable equipment near the human body, IEICE TransJ79-B-II (1996), 892–900.

8. E Antonino, M. Cabedo, M. Ferrando, and A. Valero, Acoplamientode modos resonantes en terminales moviles, Simposio URSI, Barce-lona, Spain, (2004).

9. P. Vainikainen, J. Ollikainen, O. Kivekas, and I. Kelander, Resonator-based analysis of the combination of mobile handset antenna andchassis, IEEE Trans Antenn Propag 50 (2002), 1433–1444.

10. R. Hossa, A. Byndas, and M.E. Bialkowski, Improvement of com-pact terminal antenna performance by incorporating open-end slotsin ground plane, IEEE Microwave Wireless Components Lett 14(2004), 283–285.

11. J. Anguera, I. Sanz, A. Sanz, A. Condes, D. Gala, C. Puente, and J.Soler, Enhancing the performance of handset antennas by means ofgroundplane design, IEEE International Workshop on Antenna Tech-nology: Small Antennas and Novel Metamaterials (iWAT 2006), NewYork, USA, March (2006).

12. J. Anguera, A. Cabedo, C. Picher, I. Sanz, M. Ribo, and C. Puente,Multiband handset antennas by means of groundplane modification,IEEE Antennas and Propagation Society International Symposium,Honolulu, Hawaii, USA, June 2007.

13. A. Cabedo, J. Anguera, C. Picher, M. Ribo, and C. Puente, Multi-bandhandset antenna combining a pifa, slots, and ground plane modes,IEEE Trans Antennas Propag, in press.

14. P.S. Hall and Y. Hao, Antennas and propagation for body-centricwireless communications, Artech House, Norwood, MA, 2006.

© 2009 Wiley Periodicals, Inc.

COMMENTS ON “NUMERICALCOMPUTATION OF THE GREEN�SFUNCTION OF A LAYERED MEDIAWITH ROUGH INTERFACES”

Necmi Serkan TezelElectronics and Communication Department, Istanbul TechnicalUniversity, Maslak 34469, Istanbul, Turkey; Corresponding author:tezeln@itu.edu.tr

Received 25 December 2008

1. INTRODUCTION

Recently, Altuncu et al. [1] presented a new method for evaluationof Green’s function of rough surfaces by buried object approach.However, article in [1] is exactly same as Appendix I part ofauthors’ previous article in [2] and also same as authors’ previousarticle in [3] added with new author. Moreover, numerical appli-cation of article [1] is published separately in [4] added with newauthor and subtracting two authors and also changing the order ofauthors. It is also observed that there is no citation between [1–4].Through [1–4], authors unethical behaviors such as duplications,violation of copyright agreements, and adding unfair author can beclearly observable.

REFERENCES

1. Y. Altuncu, A. Yapar, and I. Akduman, Numerical computation of theGreen’s function of a layered media with rough interfaces, MicrowaveOpt Technol Lett 49 (2007), 1204–1209

2. Y. Altuncu, A. Yapar, and I. Akduman, On the scattering of electro-magnetic waves by bodies buried in a half-space with locally roughinterface, IEEE Trans Geosci Remote Sensing 44 (2006), 1435–1443.

3. Y. Altuncu, I. Akduman, O. Ozdemir, and A. Yapar, Numerical com-putation of the Green’s function of a layered media with rough inter-faces, The 7th International Symposium on Antennas, Propagation, andEM Theory, Guilin, China, 2006.

4. O. Ozdemir and Y. Altuncu, A numerical method for the scattering fromburied conducting objects under a rough surface, NUMELEC’06, Lille-France, November 29, 30, and December 1, 2006.

© 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2254,2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24587

ERRATUM: TUNABLE BANDSTOPFILTER-BASED DEFECTED GROUNDSTRUCTURE USING A METAL PLATE

Youngje SungDepartment of Electronics Engineering, Kyonggi University, Suwon443-760, Korea

Received 30 November 2008

ABSTRACT: Originally published Microwave Opt Tech Lett 51:160–163, 2009 © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett51: 2254–2255, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24589

In [1], the author’s affiliation was incorrect. The correct affiliationappears above.

2254 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 9, September 2009 DOI 10.1002/mop