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2564 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 57, NO. 9, SEPTEMBER 2009

Compact Patch Antenna for ElectromagneticInteraction With Human Tissue at 434 MHz

Sergio Curto, Student Member, IEEE, Patrick McEvoy, Member, IEEE, Xiulong Bao, Member, IEEE, andMax J. Ammann, Senior Member, IEEE

Abstract—Single element loop, dipole and conventional squarepatch antennas have been used as hyperthermia applicators in thetreatment of cancerous human cells at superficial depths inside thebody. A smaller novel patch antenna in very close proximity to aphantom tissue model produces an enhanced specific absorptionrate pattern without significant frequency detuning or impedancemismatch. The new patch increases its coupling aperture by sup-porting a combination of resonances that are also typical for loop,dipole and square patch antennas. For computation efficiency andclarity in the synthesized hyperthermia treatment conditions, sim-plified planar tri-layered tissue models interfaced with a water-bolus are used to study the permittivity loading on the antennasand the resultant specific absorption rates.

Index Terms—Human tissue, Hyperthermia applicator, specificabsorption rate (SAR).

I. INTRODUCTION

E XTERNAL radio-frequency/microwave hyperthermia an-tenna applicators are designed to non-invasively couple

electromagnetic (EM) energy through human skin as an adjunctanti-cancer treatmentwithanionizing-orchemo-therapy[1]–[5].The energy is deployed in regions with cancerous tumor-massesto elevate the temperature to approximately 42–45 . Since tu-mors have reduced rates of temperature cooling due to naturallyimpeded blood flow, the non-ionizing application aims to se-lectively infuse the additional energy without damaging the en-closing healthy tissue. Benefits include the direct kill of raisedtemperature tumorous cells, increased cell oxygenation, stimu-lation of the immune system, increased metabolic activity and animproved drug uptake in cells.

Enhancing tumor temperatures with EM energy is complex.Determining factors include the type, size and proximity of theapplicator, the frequency of the power source, the applied-fieldpolarization and the non-uniformity of patient anatomies [6].Additionally, differing physiological responses to localized ele-vated temperatures and the consequent changes in the dielectric

Manuscript received April 30, 2008; revised February 26, 2009. First pub-lished July 07, 2009; current version published September 02, 2009. This workwas supported in part by the Irish Research Council for Science, Engineeringand Technology’s Embark Initiative Postgraduate Scholarship Scheme and inpart by the Science Foundation Ireland through the Centre for Telecommunica-tions Value-chain Research.

S. Curto and P. McEvoy are with the Antennas and High Frequency ResearchGroup, Dublin Institute of Technology, Dublin 8, Ireland.

X. Bao and M. J. Ammann are with the Antennas and High Frequency Re-search Group, Dublin Institute of Technology, Dublin 8, Ireland and also withthe Centre for Telecommunications Value-chain Research (CTVR), Dublin In-stitute of Technology, Dublin 8, Ireland (e-mail: [email protected]).

Color versions of one or more of the figures in this paper are available onlineat http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TAP.2009.2027040

properties of the tumor can produce time-dependent variancesduring treatment.

A patient’s sensitivity to contact pressure by an applicatorrelates to the severity of the tumor growth and their tolerance isincreased if the device is lightweight. Similarly, smaller antennadimensions allow a better fit to concave anatomical areas andcan minimize power loss due to separation distance from thetumor region.

When in close proximity to a patient, the antenna perfor-mance is dependent on several influences. The waterbolus[7]–[9] and the patient’s tissue [10], [11] impose a bulk load ofhigh permittivity on the antenna’s radiating near-field and/orFresnel regions. The thicknesses and depths of the constituentskin, fat and muscle layers in human tissue alter considerablyacross the body and among patients [12]–[14]. An antenna thatremains sufficiently matched to the source frequency during un-loaded and variably-loaded conditions can simplify the overallsystem stability. The applicator will be suitable for varioustissue loads while the system source, typically 50–60 dBm, willhave reduced vulnerability to destructive power reflections.

Depending on the spectrum jurisdiction, hyperthermia ap-plicators [6] have exploited frequencies in various ISM bands(or similar) at 27, 434, 915 and 2450 MHz. The longer wave-length of 434 MHz has shown a uniform specific absorptionrate (SAR) distribution and a greater penetration depth than915 MHz [15] and 2450 MHz [16]. Holt employed 434 MHzthroughout thirty years of successful cancer treatments [17].However, when lighter-weight, low-permittivity dielectric sub-strates are used for lower frequency antennas, it is usually nec-essary to increase the dimensions for efficient coupling from thelonger wavelength resonant modes.

While hyperthermia array applicators [18], [19] with sophis-ticated control systems [20], [21] offer advanced targeting fortreating different cancers, a range of complementary single el-ement designs continue to offer simple solutions [22]. Various434 MHz single element applicator types have been reportedand of the peak SAR or temperature values is used tocompare the penetration depths for the following references.The theoretical penetration depth due to a 120 mm 160 mmdielectrically loaded waveguide aperture was in[23]. By substituting the dielectric with water to overcome tissuehotspots close to the aperture, an applicator size was further re-duced to 28 mm 56 mm and achieved penetrationdepth [24]. While the aperture efficiency of these approachesits desirable, the cumbersome dimensions of practical imple-mentations would also have to be considered. The deposited en-ergy area was enhanced by a 100 mm 100 mm flared hornaperture with dielectric inserts and while applicator volume and

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CURTO et al.: COMPACT PATCH ANTENNA FOR ELECTROMAGNETIC INTERACTION WITH HUMAN TISSUE AT 434 MHZ 2565

weight remained large, the penetration depth improved to[8]. The analytical optimization of a 90.3 mm 125.5

mm water-loaded modified box-horn in [16] further enhancedthe SAR penetration depth to 40.1 mm but increased the appli-cator volume.

Microstrip solutions offer several ergonomic advantages overwaveguide and horn approaches [25], [26]. A 434 MHz mi-crostrip shorted loop on a circa 87 mm groundplane with 3.2mm profile was optimized for penetration depth [27].To reduce an applicator size, a higher permittivity design re-sulted in a rectangular printed patch on a 50 mm 70 mm 25mm, substrate [28] with a similar penetration to [27].A 5.5 mm profile microstrip applicator with a 150 mm 160mm dipole-like radiator produced a larger aperture of tangential

-fields and a penetration depth of [22].The dominant energy deposition patterns due to applicators in

[8], [27]–[31] are considered with homogeneous phantoms butthe effects of superficial hotspots due to inhomogeneous phan-toms with fat layers should not be discounted [23]. Tri-layeredskin-fat-muscle tissue models with fixed layer thicknesses [16],[24] have provided further detail but do not quantify the effectsfor the range of layer thickness in human tissue.

A novel 434 MHz compact patch antenna with an optimizedSAR performance next to a waterbolus and various planarphantom tissue models are presented in this paper. The com-pact antenna geometry contains the shapes of a loop, dipoleand square patch designs. The simulated analysis contraststhe compact patch with these basic antenna elements and theapplicator performances are assessed withfor variable skin-fat-muscle tissue layer thicknesses. The fre-quency detuning due to different separation distances fromthe load is also considered. The proposed compact applicatorremains ergonomically shaped while it achieves a deeper SARpenetration than the aforementioned referenced designs andis insensitive to variations in tissue layer thicknesses and tovariations in the proximity from the tissue models.

II. MATERIALS AND METHODS

A. Antennas Geometries

Despite being optimized for unloaded far-field performanceat 434 MHz, treatment clinics have successfully used loop [17],[32], dipole [18] and conventional square patch [33] applicatordesigns. The full-wavelength wire loop antenna dimensions area loop inner radius of 113.5 mm, a loop outer radius of 115.5mm and a feed gap of 1.8 mm. The half-wavelength wire dipoleantenna has the specifications: a wire length of 324.8 mm, a wireradius of 1.0 mm and a feed gap of 1.8 mm. The half-wavelengthsquare patch antenna [34] has the dimensions: a patch length of182 mm and a groundplane length of 232 mm on Taconic RF35 ( ) dielectric substrate of thickness 2.97 mm. Theradiating patch and groundplane are centered on the origin ofthe rectangular coordinate system and the offset feed point islocated at , .

Fig. 1 shows the proposed compact patch antenna whichcomprises a circular patch of radius , a concentric an-nular ring of inner radius and outer radius , on 130

Fig. 1. Proposed compact patch antenna: (left) the front annular-ring/patch sur-face, (right) the rear groundplane/slots surface.

mm 130 mm 2.97 mm of Taconic RF 35 dielectric sub-strate ( ). The groundplane extends to the four edgesand has two rectangular slots, of width , that intersect animpedance matching circular slot, of radius , positionedconcentrically behind the circular patch. The rectangular slotsare unequal lengths and . The optimized dimensions are:

, , , ,, , . The 50 feed

is in the concentric annular ring at the rectangular coordinatesand the center of the circular patch coincides

with the coordinate origin.When loaded by the tissue models, the 434 MHz resonant

lengths on the loop and dipole wire antennas become shorterthan the mechanical (free space) dimensions. Consequently,their effective electrical lengthening produces anti-phasedcurrent reflections that superimpose on the shortened reso-nances to reduce the radiating efficiency. To repair the radiatingefficiency of the wire antennas next to the tissue loads, theshortened loop and dipole antennas were also compared. Theshort-loop inner radius is 76.5 mm and outer radius is 78.5 mm.The short-dipole length is 239 mm and both geometries have afeed gap of 1.8 mm.

B. Waterbolus and Phantom Tissue Model

Parameters for inhomogeneous body tissues are defined[35] and whole-body electromagnetic phantoms with highlyresolved and detailed subterraneous geometries [36], [37] existfor in-silico analysis [38]. To minimize computational resourcesand for clarity, a tri-layered tissue model was used. The in-homogeneous planar tissue model represents the skin, fat andtransverse fiber of muscle [39] and a waterbolus containingde-ionized water was added at the skin interface for superficialtissue cooling. The model dielectrically loads the antenna fieldsand renders the principal SAR pattern due to the coupled energy.Table I details the dielectric parameters of permittivity ( ),conductivity ( S/m) [8], [35] and density ( Kg/m) [40] at 434MHz. The square side dimension of the waterbolus and tissuemodel was 458 mm (5 ), where is the wavelength insidethe muscle. The thickness of the tissue models was limited to 100mm, since the muscle layer depth had sufficient losses to discountreflections that would otherwise occur from inhomogeneousfeatures in full body phantoms [39].

For all body regions, the skin thickness ranges from minimaat the thorax, abdomen, spine and limbs in children to maximaat the adult thorax [14]. In this study, the lower and upper limit



TABLE IPERMITTIVITY, CONDUCTIVITY, DENSITY AND THICKNESS OF TISSUE MATERIAL FOR 434 MHZ

Fig. 2. �� with homogeneous phantom for compact antenna.

skin layer thicknesses of 0.4 mm and 2.6 mm were considered.If obese conditions are disregarded, fat storing adipose tissuethicknesses range from 0 mm to 23.2 mm [12]. To account forgreater variations [41], fat layer thicknesses of 0 mm, 15 mmand 30 mm were evaluated. The waterbolus was 5 mm thick.

C. Methodology

The key performance criterion for the antennas is the effi-cient transfer of energy into the layered tissue models. The an-tenna input impedances, resonant surface currents and the elec-tric near-fields were analyzed to interpret the basis for the SARresponses due to the four basic applicator types. Practical dis-tances between the antenna and waterbolus which correspondedwith fractional wavelengths were selected. Evaluation studiesfor all of the antennas were made at 43.2 mm ( ), 10.8mm ( ), 8.1 mm ( ), 5.4 mm ( ) and 2.7 mm( ) with each of the various combinations of tri-layeredtissue thicknesses which are summarized in Table I.

The compact antenna geometry was initially optimizedwithout tissue loading and evolved through several iterations.Beginning as a square patch, an equivalent circular patch wascreated and the radius was subsequently reduced by addingthe annular ring. The dimensions were further reduced by theinclusion of the slots in the groundplane. The geometry param-eters were refined for better SAR when near the waterbolus andphantom tissue loads.

Using a 3.4 GHz PC with 4 Gbytes of RAM, the applicatorgeometries were modeled in CST’s Microwave Studio [42].Memory requirements ranged from 224 Mbytes for the dipolenear the waterbolus and phantom combination to 551 Mbytesfor the square patch. Fig. 2 illustrates good agreement between

Fig. 3. �� for 43.2 mm antenna-waterbolus distance.

Fig. 4. �� for 2.7 mm antenna-waterbolus distance.

the numerical and measurement result for the compact patchwhen placed 5.4 mm from a load consisting of a waterbolusand homogeneous 10 g/l saline solution phantom [19].

III. RESULTS AND DISCUSSION

The illustrated results are a review of the experiments that in-vestigate the modeling accuracy and compare the different an-tenna types by considering the frequency detuning and matchedimpedance stability, the patterns of electric field intensity andthe resultant specific absorption rate patterns, normalized to 1watt of antenna input power. Figs. 3–9 show the tissue loadingconditions in the various parameter studies due to an interme-diate dimensioned phantom with 2.6 mm skin, 15 mm fat and82.4 mm muscle.



Fig. 5. Electric field distributions for 2.7 mm antenna-waterbolus distance. (a)Loop, (b) short-loop, (c) dipole, (d) short-dipole, (e) conventional square patch,(f) compact patch. Plots (a)-(b) in the plane � � ��, plots (c)-(e) in the plane� � � ��, and plot (f) in the plane � � �� .

A. Matched Impedance

The S11 simulations in Figs. 3–4 are used to compare theantennas for frequency detuning stability and their matchedimpedance. The antenna-waterbolus distance of 43.2 mm doesnot significantly detune the free-space dimensioned antennasfrom 434 MHz but the short-loop and short-dipole resonateat frequencies that are too high. The impedance match of thecompact patch resonant frequency remains sufficient stablewhen the separation distance is reduced by a small wavelengthfraction of 40.5 mm ( ) to 2.7 mm. The other antennadesigns exhibit a higher sensitivity to this change in permittivityloading.

B. Electric Field Patterns

The electric field patterns for the different antenna types at2.7 mm distant from the waterbolus and tissue model are shownin Fig. 5. In the case of the loops, the flux lines curve with thecircumferences and are tangential to the skin surface. The shortloop has a greater intensity and consequently a greater couplingcompared with the detuned full-wavelength loop. Similarly, thedipole field patterns are tangential with the skin but the inten-sity of aligned fields exceeds that of the loops. The shorter, tuneddipole produces a deeper tissue penetration distributed along thestructure. The conventional square patch presents fields normalto the tissue and results in the weakest coupling. The compact

Fig. 6. SAR at tissue surface for 2.7 mm antenna-waterbolus distance. (a)Loop, (b) short-loop, (c) dipole, (d) short-dipole, (e) conventional square patch,(f) compact patch.

Fig. 7. SAR sections for 2.7 mm antenna-waterbolus distance (a) loop, (b)short-loop, (c) dipole, (d) short-dipole, (e) conventional square patch, (f) com-pact patch. Plots (a)-(b) in the plane � � � ��, plots (c)-(e) in the plane� � � �� and plot (f) in the plane � � �� .

patch electric field pattern is a converging distribution of tangen-tial fields focused at the patch center and it achieves the highest



Fig. 8. SAR at tissue surface for compact antenna. (a) Antenna geometry andcoordinate system. Antenna-waterbolus distance: (b) 43.2 mm, (c) 10.8 mm, (d)8.1 mm, (e) 5.4 mm, (f) 2.7 mm.

Fig. 9. Compact antenna SAR cross-sections (plane � � �� ) for antenna-waterbolus distances: (a) 43.2 mm, (b) 10.8 mm, (c) 8.1 mm, (d) 5.4 mm, (e)2.7 mm.

coupling penetration into the tissue. In general, inspection of an-tenna geometries and the electric fields next to the tissue showthat a higher coupling corresponds with an increased apertureof tangentially distributed fields.

C. Specific Absorption Rate Patterns

The plots show the skin surface profile and the cross-section;in Figs. 6–7 due to the applicators being 2.7 mm distant and inFigs. 8–9 due to compact patch at various distances. The scale isclamped at 1 W/Kg for finer resolution illustration of the lowerand medium SAR patterns.

By inspection, Fig. 6(a) and (b) shows that SAR profilesof the loop and short-loop align to the circumference of thewire elements and that the peak values, 0.27 and 0.54 W/Kgrespectively, are located near the feed points. Under the loadedconditions, the shorter loop sustains an even distribution ofenergy with 3.66 at the threshold;while in contrast, the shortened resonant current length onthe larger loop produces a very low SAR diagonally oppo-site the feed. Fig. 6(c) and (d) illustrates that the dipole andshort-dipole elements have larger patterns, 6.79 and 89.44

respectively, at the threshold. Thepeak values, 0.52 and 0.95 W/Kg respectively, are centered onthe feed points. SAR patterns due to the conventional squarepatch and the compact patch are illustrated in Fig. 6(e) and (f).In the square patch, the radiating edge adjacent to the feed pointdominates the SAR profile while the pattern due to oppositeedge is reduced. Peak values are less than 0.07 W/Kg and alarge null exists in the patch center. Theprofile of the compact patch is dominant at the two locationswhere a diagonal line through the feed point intersects withthe loop aperture. The area covered is 91.52 and the peakvalue is 1.32 W/Kg.

Fig. 7 illustrates the absorption patterns of the peak SARphantom cross-sections for each of the antennas. Shortening theloaded loop antenna circumference [see Fig. 7(a) and (b)] in-creases both the SAR penetration depth into the muscle layerand the peak value by a factor of three to 0.3 W/Kg at the loopcenter point. The 0.5 W/Kg penetration depth for the short-loopis 0.64 cm. Similarly, the short-dipole SAR cross-section ex-ceeds that for the dipole [Fig. 7(c) and (d)] by a factor of twowith a level of 0.4 W/Kg. The SAR pattern is concentrated atthe feed point but is distributed evenly across the length of theshort-dipole. The 0.5 W/Kg penetration depths for the dipoleand short-dipole are 0.57 cm and 2.89 cm, respectively. Theconventional square patch SAR pattern cross-section [Fig. 7(e)]shows values of about 0.06 W/Kg in the patch center reachingthe muscle layer. The SAR cross-section of the compact patch[see Fig. 7(f)] is concentrated within the smaller aperture and itexhibits the deepest tissue penetration. The 0.5 W/Kg thresholdis 5.21 cm below the surface and the penetration depth is63 mm.

Figs. 8–9 show the SAR front profile and cross-section pat-terns for the compact patch as the antenna-waterbolus separa-tion distance reduces. Despite the increased permittivity load onthe antenna electric fields, the resonant modes remain matchedat the source frequency and the SAR increases due to improvedtissue coupling. The similar SAR profiles for the 5.4 mm and 2.7mm separation distances show that the compact patch is insensi-tive to changes in high dielectric loading at very close proximi-ties. Table II compares the dimensions and SAR values for each



TABLE IISUMMARY OF ANTENNA DIMENSIONS, PEAK SAR and SAR PATTERN PARAMETERS FOR 2.7 MM ANTENNA-WATERBOLUS DISTANCE (NORMALIZED TO 1 W

ANTENNA INPUT POWER)

TABLE IIITISSUE SAR PENETRATION FOR VARIOUS COMBINATIONS OF SKIN, FAT and MUSCLE LAYER THICKNESSES FOR 2.7 MM ANTENNA-WATERBOLUS DISTANCE

(NORMALIZED TO 1 W ANTENNA INPUT POWER)

of the antennas. The resultant SAR levels are primarily a func-tion of the antenna geometry and the compatibility of field cou-pling with the tissue at a given distance. Reducing the separa-tion distance further increases the SAR, provided the antenna re-mains frequency and impedance matched with the source. Vari-ations in the tissue layer thickness are less influential on the SARrates. The thicker skin layer produces a reduced SAR penetra-tion and the thickest layer of fat results in greater penetration.The differences in SAR due to the tissue layer thickness changesare summarized in Table III.

D. Resonant Function of the Compact Patch

The compact patch area is 31% of the conventional squarepatch and 40% of the loop, and compared to the dipoles, thesmaller dimensions make it an improved ergonomic shape forplacing next to the human body. The antenna frequency is ad-justed by coupling resonant currents on the circumferences ofthe circular patch ( ) and the annular ring ( ). The orthog-onal groundplane slots disrupt the resonant currents on the cir-cular patch and annular ring to reduce the overall patch dimen-sions. Offsetting the slot lengths, and , increases the band-width and broadening the slot widths, , results in a second-order enhancement for the -factor.

The offset lengths and width of the slots were iteratively opti-mized to prevent mismatch and for antenna resonant frequencystability without and with tissue loading. The compact patchinput impedance is characterized by a pair of resonance modes.At very close distances to the waterbolus-tissue load, the pairedresonance modes combine to be indistinguishable. As the an-tenna approaches the waterbolus, the loaded currents on thegroundplane constrict to the periphery of the slots. Unlike thewire element antennas, changes in the input impedance of thecompact patch are desensitized by the dielectric substrate which

shadows/buffers the near-field evanescent modes from directloading by the tissue. The bandwidth is increased (Figs. 3–4)and the input impedance mismatch is reduced. Positioning thefeed point in the annular ring matches it with 50 and cre-ates a SAR pattern that converges concentrically as opposed tolocating the feed in the circular patch which produces a lowerpowered diverging SAR distribution.

IV. CONCLUSION

The performance of a new compact-patch hyperthermia ap-plicator antenna for the treatment of superficial cancer cells hasbeen described. The design is contrasted with basic loop, dipoleand conventional square patch antennas which have been pre-viously used in clinical settings. It also has low-cost, ease ofmanufacture and low profile advantages over other waveguideand horn applicators. The geometric parameters are optimizedfor size reduction, high SAR, frequency detuning stability and amatched input-impedance bandwidth at various distances fromthe waterbolus and layered tissue models.

The slotted features in the antenna geometry afford a 69%area reduction with respect to the conventional square patch de-sign and also prevent load suppression of the resonant modes.The dominant electric field flux lines on the antenna are tan-gentially aligned to produce a larger coupling aperture with thetissue layers. This results in a SAR penetration depth of 63mm which exceeds the performance of other waveguides, hornand microstrip designs.

ACKNOWLEDGMENT

The authors would like to thank TACONIC Advanced Dielec-tric Division for providing the materials to make the antenna andto acknowledge the biomedical guidance from Mr. V. Thorne,Dr. H. Tinsley and Dr. J. Murphy.



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Sergio Curto (S’06) was born in Salamanca, Spain.He received the Technical TelecommunicationEngineering degree from the Universidad de Alcala,Spain, and the B.Eng. degree in computer and com-munications engineering from the Dublin Institute ofTechnology (DIT), Dublin, Ireland, in 2005, wherehe is currently working toward the Ph.D. degree.

In 2007, he visited the Institute for Infocomm Re-search, Singapore, where he worked on the design,analysis and measurement of antennas for medicalapplications. His main research interests include the

electromagnetic interaction antenna-human tissue, hyperthermia treatment, mi-crowave imaging and ultrawideband antennas.

Patrick McEvoy (M’02) received the M.Eng. degreein electronic communications engineering from theUniversity of Hull, U.K. (including a six-monthassignment to L’Institut Supérieur d’Electroniquede Paris, France) in 1998 and the Ph.D. degree inmicrowave antenna engineering from LoughboroughUniversity, U.K., in 2007.

Previously, he was a Research Manager withCentre for Mobile Communications Research,Loughborough University, where he worked onswitched antennas for handheld terminals, applica-

tions of metamaterials and low specific absorption rate antenna design. He has11 years of applied academic research and industrial experience that includesdesign, high-volume manufacturing and measurement systems for miniaturizedmicrowave antennas. He is currently a Senior Researcher with the Antenna andHigh Frequency Research Group, Dublin Institute of Technology. His researchfocus is currently on hyperthermia applicators, ultrawideband antennas forfrequency and time-domain applications and the integration of antennas withsolar voltaic devices. He has published over 40 scientific papers and has helpedto organize four international conferences on antennas and propagation.

Xiulong Bao (M’09) received the B.Sc. degree inphysics from the Huaibei Coal Industry Teachers’College, Anhui Province, China, in July 1991 andthe M.Sc. degree in physics and the Ph.D. degreein electromagnetic field and microwave technologyfrom Southeast University, Jiangsu Province, China,in April 1996 and April 2003, respectively.

After graduating, he was a Postdoctoral Re-searcher at Shanghai Jiaotong University, Shanghai,China, before going to Ireland in 2005. He is cur-rently a Senior Research Associate with the Centre

for Telecommunications Value-chain Research (CTVR) Antenna Group,School of Electronic and Communications Engineering, Dublin Institute ofTechnology, Dublin, Ireland. His broad research interests include analysisand design of various small and circularly polarized antennas, such as GPSantennas, multiple-band antennas, RFID antennas, a DTV antenna, handset

antennas, ultrawideband (UWB) antennas and the design and application ofmetamaterial/EBG structures. He is also active in the study of electromagneticscattering, electromagnetic numerical computation (FDTD, PSTD, FDFDand MOM methods) and the study of electromagnetic wave propagation andantenna theory. He has published 27 peer-reviewed journal papers and 25conferences articles.

Dr. Bao is was a Technical Program Committee member for the 65th IEEEVehicular Technology Conference, Dublin, 2007.

Max J. Ammann (M’96–SM’08) received theCouncil of Engineering Institution Part II degree in1980 and the Ph.D. in microwave antenna designfrom Trinity College, University of Dublin, Dublin,Ireland, in 1997.

In 1986 he joined the Dublin Institute of Tech-nology (DIT), Dublin, Ireland, and was promotedto Senior Lecturer in the School of Electronic andCommunications Engineering, in 2003. He is alsothe Director of the Antenna and High FrequencyResearch Group, and also leads the antenna re-

search within Ireland’s Centre for Telecommunications Value-chain Research(CTVR). He spent eight years on radio systems engineering and antennadesign for TCL/Philips Radio Communications Systems, Dublin, where he wasresponsible for commissioning the Nationwide Communications Network forIreland’s national police force. His research interests include electromagnetictheory, antenna miniaturization for terminal and ultrawideband applications,microstrip antennas, metamaterials, antennas for medical devices and theintegration with photovoltaic systems. He has published in excess of 150peer-reviewed papers in journals and international conferences.

Dr. Ammann sits on the management committee of the EU COST ActionIC0603, “Antenna Systems and Sensors for Information Society Technologies”(ASSIST) and is active in the Antenna Sensors and Systems Work Group. Asa member of the IEEE International Committee for Electromagnetic Safety, heparticipated in the revision of the IEEE Std. C95.1, 2005 standard for SafetyLevels with Respect to Human Exposure to Radio Frequency ElectromagneticFields, 3 kHz to 300 GHz. He is also a member of the URSI Committee for Com-munications and Radio Science within the Royal Irish Academy, with expertisein Commission K: Electromagnetics in Biology and Medicine. He chaired theIEEE APS Special Session on Antennas for UWB Wireless CommunicationSystems, Columbus, Ohio, 2003 and was Chair for the Antennas and Propa-gation Track for the 65th IEEE VTC, Dublin 2007. He was the local chair forthe October 2008 EU COST IC0603 workshop and meeting in Dublin. He hasserved as an expert to industry on various antenna technologies in the com-munications, medical, aviation and electronic security sectors in Ireland andabroad. The roles have included design assessment, design solutions, techno-logical strategy reporting and assessment of compliance with international stan-dards on human exposure to electromagnetic energy. The industrial contacts alsostem from several successful transfers of fundamental design research into ap-plied solutions. He received the 2006 Best Poster Award at the LoughboroughAntennas and Propagation Conference, a Commercialization Award for workwith DecaWave Ltd. and a 2008 CST Publication Award for work on a “Wide-band Reconfigurable Rolled Planar Monopole Antenna.”


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