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[14] A. Abbosh, M. Bialkowski, J. Mazierska, and M. Jacob, A planarUWB antenna with signal rejection capability in the 46 GHz band,

IEEE Microwave Wireless Co mpon. Lett., vol. 16, pp. 278280, May2006.

[15] K. Bahadori and Y. Rahmat-Samii, A miniaturizedelliptic-card UWBantenna with WLAN band rejection for wireless communications,

IEEE Trans. Antennas Propag., vol. 55, no. 11, pp. 33263332, Nov.2007.

[16] Y. Cho, K. Kim, D. Choi, S. Lee, and S. Park, A miniature UWBplanar monopole antenna with 5-GHz band-rejection filter and thetime-domain characteristics, IEEE Trans. Antennas Propag., vol. 54,no. 5, pp. 14531460, May 2006.

[17] T. Dissanayake and K. P. Esselle, Prediction of the notch frequencyof slot loaded printed UWB antennas, IEEE Trans. Antennas Propag.,vol. 55, no. 11, pp. 33203325, Nov. 2007.

[18] L. N. Zhang, S. S. Zhong, C. Z. Du, and J. H. Chen, Compact UWBplanar monopole antenna with band-notch function, Microw. Opt.Technol. Lett., vol. 51, no. 8, pp. 19081911, Oct. 2009.

[19] M. A. Antoniades and G. V. Eleftheriades, A compact multibandmonopole antenna with a defected ground plane, IEEE Antenna.Wireless Components Lett., vol. 7, pp. 652655, Jan. 2009.

[20] M. Zhang, X. L. Zhou, J. Guo, and W. Y. Yin, A novel ultrawidebandplanar antenna with dual band-notched performance, Microw. Opt.Technol. Lett., vol. 52, no. 1, pp. 9092, Jan. 2010.

[21] W. S. Chen and K. Y. Ku, Band-Rejected design of the printed open

slot antenna for WLAN/WiMAX operation, IEEE Trans. AntennasPropag., vol. 56, no. 4, pp. 11631169, Apr. 2008.

[22] D. Z. Kim, W. I. Son, W. G. Lim, H. L. Lee, and J. W. Yu, In-tegrated planar monopole antenna with microstrip resonators havingband-Notched characteristics,IEEE Trans. Antennas Propag., vol.58,no. 9, pp. 28372842, Sep. 2010.

[23] [Online]. Available: http://www.cst.com/

Triple Band-Notched UWB Planar Monopole Antenna

Using a Modified H-Shaped Resonator

Y. Sung

AbstractA printed microstrip-fed monopole ultra-wideband (UWB)

antenna with triple notched bands is presented. By embedding a modified

H-shaped resonator with an additional outer line beside the microstrip

feedline, band-rejected filtering properties around the 3.5 GHz WiMAX

band, the 5.2/5.8 GHz WLAN band, and the X-band satellite commu-

nication band are generated. The notched frequencies can be adjusted

according to specification by altering the modified H-shaped resonator.

Sharp gain reductions occur at 3.7, 5.2, 7.5, and 7.9 GHz. However, for

other frequencies outside the notched bands, the gain is stable in the entire

UWB band.

Index TermsBand-notched antennas, bandstop filter, ultrawideband

(UWB) antennas.

I. INTRODUCTION

Ultra-wideband (UWB) technology has become the focus of much

research and development since the U.S. Federal Communications

Manuscript received December 15, 2011; revised August 13, 2012; acceptedSeptember 19, 2012. Date of publication October 09, 2012; date of current ver-sion January 30, 2013. This work was supported by the Gyeonggi Regional Re-search Center (GRRC).

The author is with the Department of Electronic Engineering, Kyonggi Uni-versity, Suwon 443-760, Korea (e-mail: yjsung@kgu.ac.kr).

Color versions of one or more of the figures in this communication are avail-able online at http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TAP.2012.2223434

Fig. 1. (a) Conventional structure. (b) Proposed structure.

Commission (FCC) approved the unlicensed use of ultra-wideband

(UWB) from 3.1 to 10.6 GHz for commercial communication purposes

[1]. An extremely broadband antenna, which is one of the essential

components in the UWB communication system, will be considered

in the frequency range from 3.1 to 10.6 GHz. Until now, various

structures have been studied to achieve wideband antennas. However,

in practical applications, antenna design for UWB applications is stillfacing many challenges. One such challenge is to avoid interference

with some other existing narrowband services that already occupy

frequencies in the UWB band, such as WiMAX in some European and

Asian countries (3.4 3.6 GHz) and IEEE 802.11a in the USA (5.15

5.35 GHz & 5.725 5.825 GHz). Furthermore, X-band satellite

communication services from 7.25 to 8.395 GHz (down link: 7.25

7.745 GHz, uplink: 7.9 8.395 GHz) also operate in the UWB band.

Therefore, it is necessary to design antennas with multiband filtering

functionality.

Some UWB antennas with notched frequency bands have been re-

ported in the published literature [2][4]. These antennas are generally

embedded with a half-wavelength structure such as an L-shaped slot

[2], an -shaped slot [3], or a U-shaped slot [4]. Also, each structure in

these antennas can generate only one notched frequency band. There-fore, multiple resonators are required in order to realize an UWB an-

tenna with multiple notched bands. The use of multiple resonators will

increase the complexity of the UWB system. This has put an additional

constraint on antenna design. Combining a single resonator with UWB

antennas to create multi-stopband antennas, to our best knowledge, is

still little reported for such applications.

In this communication, a novel, compact, printed UWB monopole

antenna with triple band-notched characteristics is proposed. By ad-

justing the dimension of the modified H-shaped resonator located be-

side the feedline, we can easily obtain triple stopbands. Compared with

the antenna reported in [5][7], this design uses a single resonator in-

stead of two and likewise realizes triple band-notched characteristics.

The proposed antenna also has a simpler configuration and is easier to

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Fig. 2. Simulated results of a conventional structure and the proposedstructure.

Fig. 3. Simulated of the modified SCRLH resonator with (a) differentlengths and (b) different lengths .

fabricate. A practical example of a UWB antenna (working from 3.04

to 11.31 GHz) is demonstrated, with one notch frequency band at 3.37

3.80GHz, one at4.26 5.85GHz, and the other at7.25 8.81GHz.

II. MODIFIED H-SHAPED RESONATOR

Fig. 1(a) and (b) shows the conventional and modified structures to

be used as the notch filter of the UWB antenna. The conventional sim-

plified composite right/left-handed (SRCLH) structure is composed of

two patches of large width , a line placed vertically , a

line placed horizontally , and a via. The two large width patches

Fig. 4. Simulated of the modified SCRLH resonator with (a) differentlengths (b) different lengths .

in the H-shape are connected to each other by a vertical line and are

connected to the ground plane through a horizontal line and a via [8],

[9]. The proposed structure is designedbased on the conventionalnotch

filter. Asshown in Fig. 1(b), an outerline was added to the conventional

structure. At the left end of the outer line, the conventional structure is

connected, while the right end is connected to the main signal line (In

Fig. 1(b), a 50 microstrip line). To simplify the design and discus-

sion, all linewidths are equally set to w. All the parameters have been

optimized by using commercial full-wave software IE3D.

In order to determine the frequency response characteristics of the

structures shownin Fig. 1, a 2 portfilter structure combining a resonator

and a 50 microstrip line was simulated. Fig. 2 shows the simulated

. All structures are printed on the substrate with a permittivity of2.2 and a thickness of 1.14 mm. In order to obtain a 50 characteristic

impedance, the microstrip feedline width was chosen as 3.5 mm. Also,

the gap between the notch resonator and the 50 microstrip line is

fixed at 0.1 mm. The simulated structures show a bandstop character-

istic at the resonant frequency. The simulation results showed that the

conventional structure without a via displayed single resonance char-

acteristics in the 7.45 GHz band, and the addition of a via resulted in

the formation of a new resonance in the 3.5 GHz band. Therefore, the

conventional structure shown in Fig. 1(a) has a dual resonance char-

acteristic. The geometrical dimensions for the conventional structure

shown in Fig. 1(a) are as follows: , , ,

, , and .

A conventional H-shaped structure has a dual resonance character-

istic, while a structure with an added outer line shows quad resonance

characteristics. Figs. 3(a) and (b) show the simulated

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Fig. 5. (a) Proposed notch element. (b) Proposed UWB antenna with triplenotch bands.

results according to the variation of length of the line con-

nected with the via (shown in Fig. 1(a)) and length . The design pa-

rameters of the H-shaped resonator are equivalent to those above, and

the design parameters of the outer line are as follows: ,

, , , , and

. From the simulated results, it is found that the resonant

frequency decreases as the length increases. In this case, the other

resonant frequencies remain unchanged. Meanwhile, it was found that

the resonant frequency of the proposed structure showed the most

noticeable changes according to the change of . From this, the res-

onant frequencies and of the proposed structure were the 2 reso-

nances of the conventional structure.The resonant frequencies and of the proposed structure are

the resonances formed due to the conventional H-shaped resonator,

whereas and are formed due to the outer line. Fig. 4 shows

the simulated results according to variation of lengths and

, which correspond to the horizontal and vertical lengths, respec-

tively. The simulationresultsshow that and changed withthe two

lengths ( and ). Notch characteristics are found in the two bands,

because the signal coupled from the main signal line to the H-shaped

resonator returns back to the main signal line along the outer line, and

the two signals meet at a phase difference of 180 [10], [11]. Appro-

priately altering each parameter allows the placement of in the 3.5

GHz band and in the 5.2/5.8 GHz band, as shown in Fig. 2. Here,

since the band occupied by satellite communication services is rather

wide at 14.6% (7.25 8.395 GHz), and were combined to im-

plement a notch band.

Fig. 6. Simulated and measured results of the proposed antenna.

Fig. 7. Simulated current distribution of the proposed structure at four resonantfrequencies. (a) 3.7 GHz, (b) 5.19 GHz, (c) 7.51 GHz, (d) 8.01 GHz

III. UWB ANTENNA WITH NOTCHED BANDS

Fig. 5(a) is the final notch element design. The structure shown in

Fig. 1(b) is not appropriate for application in real UWB antennas be-cause the length is too long. In order to reduce the notch struc-

ture size, the structure was modified into a meandering shape, with a

right-side width of 0.3 mm. As a result, is reduced to 8.2 mm. The

remaining parameters are the same as noted above. The simulated

of the notch element in Fig. 5(a) is shown in Fig. 6. Fig. 5(b) shows the

geometry of the proposed antenna which features band-notched UWB

characteristics. The antenna is implemented on the substrate with a di-

electric constant of 2.2 and a substrate thickness of 1.14 mm. By in-

serting a slit (5.2 mm 3.9 mm) underneath the microstrip feed line

on the ground plane, additional resonances are excited, and hence the

bandwidth is increased. The overall antenna size is 33 mm 25 mm.

The conducting ground plane has a size of16 mm 25 mm. The radius

of the circularradiating patch isfixed at8 mm. The width ofthe feeding

microstrip line is 3.5 mm and its characteristic impedance is 50 . The

gap distance between the radiating patch and the ground plane is fixed

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Fig. 8. Measured radiation pattern.

at 0.3 mm. The gap between the feedline and the resonator is fixed at

0.1 mm. An SMA is connected to the port of the feeding microstrip

line.

Fig. 6 shows the simulated and measured values of the reflection co-

efficient against the frequency response for the proposed antenna. The

simulated result of the reference antenna without notched characteris-

tics is also shown for comparison. It is observed from the measured

results that the designed antenna exhibits three steeply rejected bands

of 3.37 3.80 GHz, 4.26 5.85 GHz, and 7.25 8.81 GHz, while

maintaining wideband performance from 3.04 to 11.31 GHz for VSWR

2, which covers the entire UWB frequency band. The discrepancy

in reflection coefficient between the simulated and measured results is

likely to have been caused by the fluctuation of the dielectric constant

and tolerance in manufacturing. The label filter_sim in Fig. 6 refers

to the simulated result of the proposed structure in Fig. 5(a). The

Fig. 9. The peak gain.

notch band of the proposed antenna was in close agreement with the

of the structure shown in Fig. 5(a).

Fig. 7 shows the simulated current distribution on the surface of the

resonator at four frequencies: 3.7, 5.19, 7.51, and 8.01 GHz. The figureshows that the current is more sparsely distributed as it nears the areas

marked in blue, while its distribution grew denser as it approaches the

red areas. Maximum value and minimum value are set as equal in order

to allow an accurate comparison between Figs. 7(a)(d). As shown in

Fig. 7(a), the current distribution of the via is high compared with other

parts of the notch element. As a result, the geometrical parameter for

this region plays an important role in controlling the first resonance.

Compared with other parts of the notch element, a significant amount

of current is distributed on the H-shaped resonator at the third reso-

nance frequency 7.5 GHz; thus, the change in the length of affects

. As shown in the Figs. 7(b) and (d), a significant amount of current

is distributed on the outer line. Therefore, and are mainly deter-

mined by the lengths of and .The measured radiation patterns at 3, 6, and 9.5 GHz are shown in

Fig. 8. It can be seen that the antenna has a good omnidirectional radi-

ation pattern in the H-plane, and a dipole-like radiation pattern in the

E-plane. The measured peak gain in the E-plane is given in Fig. 9. The

proposed antenna exhibits three antenna gain decreases at 3.37 3.80

GHz, 4.26 5.85 GHz, and 7.25 8.81 GHz, thus clearly indicating

the effect of the notched bands.

IV. CONCLUSIONS

A novel compact microstrip-fed printed monopole antenna with

triple-notched characteristics, for use in various UWB applications,

has been presented and investigated. The desired stopband can be

achieved by adjusting the physical parameters of the H-shaped res-

onator. Implementing the H-shaped resonator in the vicinity of the

feedline does not perturb the behaviour of the radiating element, and

this is the main advantage of the proposed method. Due to its simple

structure, compact size, and excellent performance, the proposed

antennas are expected to be good candidates for use in various UWB

systems.

REFERENCES

[1] Revision of Part 15 of the Commissions Rules Regarding Ultra-Wide-band Transmission Systems, Fir st Note and Order Federal Communi-cations Commission, ET-Docket 98-153 2002.

[2] K. Shambavi and Z. C. Alex, Printed dipole antenna with band rejec-tion characteristics for UWB applications, IEEE Antennas Wireless

Propag. Lett., vol. 9, pp. 10291032, 2010.

[3] W. T. Li, X. W. Shi, and Y. Q. Hei, Novel planar UWB monopole an-tenna with triple band-notched characteristics, IEEE Antennas Wire-less Propag. Lett., vol. 8, pp. 10941098, 2009.

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[4] C. Yu, W. Hong, L. Chiu, G. Zhai, C. Yu, W. Qin, and Z. Kuai, Ultra-wideband printed log-periodic dipole antenna with multiple notchedbands, IEEE Trans. Antennas Propag., vol. 59, no. 3, pp. 725732,Mar. 2011.

[5] X.-J. Liao, H.-C. Yang, N. Han, and Y. Li, Aperture UWB antennawith triple band-notched characteristics, Electron. Lett., vol. 47, no.2, pp. 7779, Jan. 2011.

[6] Y. Zhang, W. Hong, C. Yu, Z.-Q. Kuai, Y.-D. Don, and J.-Y. Zhou,Planar ultrawideband antennas with multiple notched bands based onetched slots on the patch and/or split ring resonators on the feed line,

IEEE Trans. Antennas Propag., vol. 56, no. 9, pp. 30633068, Oct.2008.

[7] M.-C. Tang, S. Xiao, T. Deng, D. Wang, J. Guan, B. Wang, and G.-D.Ge, Compact UWB antenna with multiple band-notches for WiMAXand WLAN, IEEE Trans. Antennas Propag., vol. 59, no. 4, pp.13721376, Apr. 2011.

[8] Q. Sun, Y.-J. Zhao, L. Qiang, B. Liu, and J.-K. Wang, A planarultra-wideband antenna with dual notched bands based on SCRLHresonator, in Proc. Int. Conf. on Microwave and Millimeter WaveTechnology, May 2010, pp. 380383.

[9] F. Wei, C.-J. Gao, B. Liu, H.-W. Zhang, and X.-W. Shi, UWB band-pass filter with twonotch-bandsbasedon SCRLH resonator,Electron.Lett., vol. 46, no. 16, pp. 11341135, Aug. 2010.

[10] M. A. Sanchez-Soriano, E. Bronchalo, and G. Torregrosa-Penalva,Compact UWB bandpass filter based on signal interference tech-

niques, IEEE Microwave Wireless Comp. Lett., vol. 19, no. 11, pp.692694, Nov. 2009.

[11] W. Feng and W. Che, Novel ultra-wideband bandpass filter usingshorted coupled lines and transversal transmission line, IEEE Mi-crowave Wireless Comp. Lett., vol. 20, no. 10, pp. 548550, Oct. 2010.

An Ultra Wide Permittivity Antenna (UWPA) for Reliable

Through-Wall Communications

Daniele Pinchera, Marco D. Migliore, and Fulvio Schettino

AbstractThe aim of this communication is to describe a radiating

system specifically designed for wireless through-the-wall communica-

tions. The antenna is capable to operate on walls with relative permittivity

in the range 19 keeping a reflection coefficient lower than 10 dB.

Experimental results confirm the effectiveness of the proposed design.

Index TermsAntennas, attenuation measurement, permittivity.

I. INTRODUCTION

Through-the-wall electromagnetic wireless communication systems

have been the object of relatively little attention by the researcher and

industrial community in the past. However, they have some peculiar

characteristics making them interesting for interconnecting communi-

cation systems in complex indoor propagation environments [1][9].

A typicalexample is the interconnectionof communication networks

among different indoor environments divided by thick, possibly rein-

forced, concrete walls. Due to structural/security issues, or because the

Manuscript received March 12, 2012; revised July 18, 2012; acceptedSeptember 18, 2012. Date of publication October 09, 2012; date of currentversion January 30, 2013. This work was supported by the MIUR under PRINgrant #20093CJEJ5_002.

The authors are with the DIEI, University of Cassino and Southern Lazio,Cassino, Italy (e-mail: pinchera@unicas.it; mdmiglio@unicas.it; schet-tino@unicas.it).

Color versions of one or more of the figures in this communication are avail-able online at http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TAP.2012.2223439

Fig. 1. Schematicof theUWB patch antenna. Thesubstrate is depicted partiallytransparent in order to see the upper and lower metalization. The hole in thelower metalization is for the coupling with a coaxial cable. The dimensions forthe free parameters are reported in Table I.

network needs to be set up very quickly, it may not be possible to pro-

vide cable connections through the walls; in these cases it would be

preferable to provide wireless through-the-wall (WTTW) bridges be-

tween the networks.

Due to the low-cost of wireless systems, WTTW is a practical and

often economically attractive solution also when a wired connectionis technically possible, especially in buildings that have not been

designed considering the necessity to provide a Local Area Network

(LAN). Finally, WTTW communication could be an interesting

solution when standard wireless systems require multiple hopping

to connect two communication networks that can be directly linked

through a wall.

Broadly speaking, the goalof an electromagneticWTTW is basically

the maximization of the power that is transmitted through the wall.

The main issue of the aforementioned design is the dependence of the

design of the antenna to be mounted on the wall with respect to the

permittivity of the wall itself. Unfortunately, the dielectric properties of

stucco and concrete vary in the range 29 [10] according to a number

of parameters (humidity, aging, size of the particles, percentage of the

components, etc.), so the optimum design of the antenna would requiremeasuring the effective permittivity of the wall and thus tuning the

antenna design according to the measure.

The main aim of our work is to obtain an antenna structure capable

of achieving a good impedance for a large range of wall permittivities.

Other important characteristics for a WTTW antenna concern the gain

of the antenna, that must exhibit a small variation with the wall material

characteristics in the direction normal to the surface of the wall, in

order to guarantee an easiness of alignment of the two antennas at the

opposite sides of the wall.

A structure of this kind hasbeen designed and simulated (Section II),

and some prototypes have been built and tested in various working

environments (Section III).

II. ANTENNA DESIGN AND SIMULATION

As discussed in the Introduction, the goal is to obtain an ultra-wide-

permittivity antenna (UWPA), i.e., an antenna whose main character-

istics do not change when the dielectric properties of the propagation

medium are changed.Tothe best knowledge of the authors,no otheran-

tenna specifically designed according to ultra-wide-permittivity char-

acteristics is described in the open literature. There is, however a wide

literature on therealizationof ultra wide band antennas[11], and we are

going to exploit some of the concepts of UWB antennas in our design.

In order to clarify the relationship between UWPA and UWB an-

tennas, let us consider an antenna surrounded by a dielectric medium.

Clearly, the (working) resonating frequency of the antenna depends

on the permittivity of the dielectric medium and changes according to

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