IJETT-V4I7P161

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International Journal of Engineering Trends and Technology (IJETT) - Volume4 Issue7- July 2013

ISSN: 2231-5381 http://www.ijettjournal.org Page 3086

Design Analysis of Patch Antenna without EBG and

With Cross-Shape EBG and Analyse the Effect of

Different Feed PositionPreeti vats#1, Deepender Dabas*2

#Department of Electronics and communication, PIET, Samalkha

Panipat, Haryana, India

Abstract This paper presents Micro strip antenna design withnovel shapes of 2D-electromagnetic band-gap structure (2D-

EBG). The cross shape slots EBG are used & the effect of

different Feed position & spacing between the slots is analysed.Simulated results show improved performance of the antenna

with or without EBG slots at different feed position on thesubstrate of antenna. This ensures that bandwidth increases

greatly while size is nearly unaffected. The designed patchantenna has a size of 13.3 mm * 8.9 mm. Antenna operation in

wide band is obtained in the range of 6.5 to 7.5 GHz, when feedapplied at (2, -5) & Return loss also minimized to a good extent.

which is advantageous for transmitting information over a larger

bandwidth. Wideband antennas find its applications in mobilesensors, data collection, precision locating and tracking

applications.

Keywords Patch antenna, Cross slot, Coaxial feed,Electromagnetic band gap (EBG), Wideband antenna.

I. INTRODUCTIONA micro strip patch antenna is widely used in

communication devices due to its small size, thin profile

configurations, low cost and conformity. In spite of theseremarkable advantages, the patch suffers some serious

drawbacks like low bandwidth (due to small size). Bandwidthcan be increased but at the cost of size of the patch, making it

large and bulky. To overcome this problem, a multiple-layer

dielectric substrate has been used to improve bandwidth [1].

In this paper bandwidth improvement and reduction in losseshas been achieved by use of different EBG design.

In this paper, to suppress surface wave losses, parts of thesubstrate surrounding the patch have been strategicallyremoved, and thereby increase gain and bandwidth range [2].

It is well known that for a particular resonant frequency, the

bandwidth increases with increase in size of patch antenna,

with high dielectric constant [3, 4]. The patch antenna of low

dielectric has a moderate bandwidth but large size. To includethe quality of both high and low dielectric, two substrates

have been combined, i.e., high bandwidth and low patch sizerespectively [5]. In this paper, the effect of feeding on thecharacteristics of a patch antenna (gain, bandwidth, and

radiation pattern) especially on loss return, by using twodifferent feeding points (dx, dy): This can be achieved by

varying the position for dx and dy values that promote the

increase of bandwidth and give the advantage of low returnlosses.

II. COMPARISONOFANTENNADESIGNComparison of Antenna design is made on the basis of

without EBG, using Cross EBG slots of different dimensionsand Co-axial probe feed applied at different positions.

A.Antenna design without EBG structureA patch antenna without EBG has been studied of

dimension 8.9*13.3 with feed applied at (1, 4.5). Fig. 1 shows

the designed patch. The return loss (S11) obtained is of -10 db

at a frequency of 8.5 GHz is shown in Fig.

Fig. 1.Designed Patch Antenna with feed at (1, 4.5)

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Fig.2.Return losses (S11) of antenna without EBG structure

To eliminate the effect of surface wave Electromagneticband gap (EBG) structures were used. Various shapes of EBG

can be used like circular, rectangular, star and H-shape.

III.ANTENNA DESIGN UNING CROSS-SLOT EBG STRUCTURETo eliminate the effect of surface wave electromagnetic

band gap (EBG) structures were used. Various shapes of EBG

can be used like circular, rectangular, star and H-shape.

A.Antenna designs using 2*2 Cross-slots EBG Structure:Cross-slots are cut at the ground plane of the patch antenna.

This EBG structure consists of two layers and the radiatingelement printed on the upper surface of the top layer. The

bottom layer carries an array of 2*2 Cross slots. The patch

antenna with EBG structure is shown in Fig. 3. A substrate ofdimension (Lsub*Wsub) of 22*22 mm, thickness (h) of 1.5

mm, dielectric constant of 4.65 and loss tangent of 0.02. Cross

slots array size 2*2 & of dimension (Lslot*Wslot) 1*4. A

patch is placed on the dielectric substrate at a height of 1.6mm having width of patch 13.3 mm and length of patch 8.9mm. Co-axial feed applied at the centre of the patch.

Fig.3. Patch Antenna with 2*2 Cross-slots EBG

The return loss from the designed patch obtained in range

of ( -10 to -12 dB) at wide band frequency of 5.8 to 6.3 GHzas shown in figure 4. As the central frequency is 5.9 GHz, so

Bandwidth % obtained is 10.1695 %.

Fig.4 Return losses (S11) of antenna with U slot EBG structure

B. Antenna design using 7*7 Cross-slots EBG Structure atfeed position (3, 4.5):

Cross-slots are cut at the ground plane of the patch antenna

of array size 7*7.The designed patch with Cross EBG slots is

shown in fig. 5. A substrate of dimension (Lsub*Wsub) of22*22 mm, thickness (h) of 1.5 mm, dielectric constant of

4.65 and loss tangent of 0.02. Cross slots array size 7*7 & ofdimension (Lslot*Wslot) 0.5*2. The spacing between eachslots is of 1mm. A patch is placed on the dielectric substrate at

a height of 1.6 mm having width of patch 13.3 mm and lengthof patch 8.9 mm. Co-axial feed applied at (3,4.5).

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Fig.5. Patch Antenna with 7*7 Cross-slots EBG at feed position (3, 4.5)

The return loss from the designed patch obtained in rangeof (-11 to -12 dB) at a frequency of 7.1 GHz as shown infigure 6 a narrow band is obtained in this case & also the

return loss is not minimized to a good extent.

Fig 6.Return loss (S11) of antenna with 7*7 cross slot EBG structure

D. Antenna design using 7*7 Cross-slot EBG Structure atfeed position (2, -5):

The schematic diagram of the coaxial probe fed crossshaped EBG ground plane antenna is shown in Fig. 7. On the

ground plane cross slots of dimension 7*7 mm slots are cut.The feed was given at the (2, -5). The antenna designed on a

dielectric substrate with dimension of (2222 mm). The EBG

structure has cross slots of 21 mm unit cells; each cross slot

is at a distance of 1mm. The dielectric substrate has a

thickness of 1.6 mm, relative permittivity (1) of 4.65 and losstangent () of 0.02. A rectangular radiating patch of (Lp*Wp)

of dimensions 8.9*13.3 mm is printed on the top layer.

Fig.7. Patch Antenna using 7*7 cross-slots EBG at feed position of (2, -5)

The return loss of this antenna obtained between -35 to -40

dB at 7 GHz. Wide band of 6.7 to 7.45 GHz is obtained &

Band width % of 10.7143% is obtained, making it a wideband application antenna. This antenna finds its application in

wide band operations. The return loss is shown in figure 8.

Fig 8.Return loss (S11) of antenna with cross slot EBG structure

IV.RESULTANDCONCLUSIONSIt is observed after simulation on the ZELAND IE3D

software that a wide band antenna is obtained using cross

slotted EBG structures. The EBG structure not only reducesthe surface losses but also help in making a wide band

antenna, without affecting the size of the antenna. As without

EBG, we observed that narrowband antenna is obtained andthe return losses was also large. While by using cross slotted

EBG on micro strip patch antenna return loss is minimized as

well as wideband is also obtained. The 2*2 cross slot-antennacan be used for Wireless LAN application in the frequency

range 5.8 to 6.3 GHz. The 7*7 cross slotted antenna givesbetter results when the feed is applied at (2, -5). These

antennas provide good impedance matching, stable radiationpatterns & return loss was minimized in the range of -35 to -

40dB. It is also observed from the simulation result that thedislocation of the probe feed to patch highly effects the

characteristics of the micro strip patch antenna like return

losses but does not affect the directivity of the antenna.

ACKNOWLEDGMENT

I am highly grateful to Er. Deepender dabas (Assist. Proff.in Electronics & Communication Engineering Department).

Without his wise counsel and able guidance, it would have

been impossible to complete the dissertation work in thismanner.

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