COMPACT PATCH ANTENNA PARAMETERS ENHANCEMENT USING LEFT-HANDED METAMATERIAL IN L-BAND

7/30/2019 COMPACT PATCH ANTENNA PARAMETERS ENHANCEMENT USING LEFT-HANDED METAMATERIAL IN L-BAND

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INTERNATIONAL JOURNAL OF ADVANCED ELECTRONICS & COMMUNICATION SYSTEMSApproved by CSIR-NISCAIR ISSN NO: 2277-7318

ISSUE 3 VOL 1, JAN-FEB, 2013 PAPER ID 11537-42836-1

COMPACT PATCH ANTENNA

PARAMETERS ENHANCEMENT USING

LEFT-HANDED METAMATERIAL IN L-BAND

Bimal Garg1, Ranjeet Pratap Singh Bhadoriya

2

1,2Dept. of Electronics Engineering, Madhav Institute of Technology & Science,Gwalior, India

[email protected]

[email protected]

Abstract- In this paper, the authors reduces the return loss to agreat extent by using triangular shaped metamaterial

structure in L-Band. First, the authors formulate a generaltheory for inhomogeneously loaded subwavelength rectangularpatch antennas. The system is firstly modelled by ComputerSimulation Technology Software (CST-2010). With the help of

CST-2010, the return loss, directivity, radiation pattern &

efficiency of compact rectangular Patch Antenna operating at

2GHz frequency and rectangular Patch Antenna along with

designed Metamaterial shape have been evaluated in this work.

After evaluation, the Double Negative Metamaterial properties of

the proposed Structures are verified by using NRW (Nicolson-

Ross-Weir) approach. Basically metamaterial neither exists in

nature nor are they found in naturally occurring media.

Metamaterial itself has no property instead it achieve properties

from structural design rather than composition. In this designing

process CST-MWS software is used for the simulation process

and later on for the NRW approach Microsoft Excel is used.

Keywords: Metamaterial, Nicolson Ross Weir (NRW), Permittivity,Rectangular microstrip patch antenna (RMPA), Return loss.

I. INTRODUCTIONThe peremptory for small, compact, low cost antennas has

grown tremendously over the past years, due to the desire for

reduced antenna size in both military and commercial areas.There has been a lot of analysis published on the improvement

of the performances of patch antennas. Most of the solutions

proposed were to use an array of several antennas. The main

disadvantage of this method is the feeding of each antenna and

also from the coupling between each element. Many differentarousing curiositic solutions have been suggested. The firstwas to make use of a superstrate of either high permittivity or

permeability above the patch antenna [2] and later proposed

recently was to sandwich the antenna by dielectric layers of

the same permittivity [3], [11].

Now in this new study it is going to be revealed as

improvement in performances of a rectangular patch antennawhen a left-handed medium (LHM) [1], [12] metamaterial

is placed above it. In this paper it is going to be present a new

design of patch antenna system, in which a metamaterial

structure is introduced as the cover of the antenna. The

radiation pattern, bandwidth, and directivity of the new patchantenna are studied by full-wave simulations, combined with

boundary Conditions. The effects of the cover layer on theperformance of the antenna are also analysed. After

comparison with the RMPA alone and post metamaterial

introduction it has been seen that there are lots of parameter

improvement took place such as; directivity, return loss,bandwidth and gain. Computer Simulation Technology-

microwave studio (CST-MWS) Software has used for the

imitation. MS Excel has been used to justify the Double

Negative properties of the proposed design.

II. DESIGNINGMETHODANDSIMULATEDRESULTS

For design purpose first of all, length and width of the

patch antenna for 2GHz has been calculated. The microstrip

patch antenna (Rectangular) parameters were calculated by

these formulas.

A. Desired Parametric Analysis [3][4]:Calculation of Width (W):

. (1)Where,

c = velocity of light in free space,r= Substrates Dielectric constant

Effective dielectric constant will be calculated by:

. (2)Actual length of the Patch (L)


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INTERNATIONAL JOURNAL OF ADVANCED ELECTRONICS & COMMUNICATION SYSTEMS

Approved by CSIR-NISCAIR ISSN NO: 2277-7318


L =Leff- 2L . (3)

Where,

Leff . (4)Length Extension will be Calculate by

()() . (5)After parameter calculation designing has been done on theCST-MWS. The Patch Antenna (in fig. 1) is designed using

the calculated parameters shown below in Table 1.

Table 1: RMPA Specifications:

Parameter Dimensions UnitDielectric

Constant (r)

4.3 -

Thickness (h) 1.6 mm

Operating

Frequency

2 GHz

Length (L) 35.0462 mm

Width (W) 45.2721 mm

Cut Width 5.0 mm

Cut Depth 10.0 mm

Path Length 33.03605 mm

Width Of Feed 3.009 mm

Fig. 1: Rectangular microstrip patch antenna at 2 GHz (alldimensions in mm).

Designed RMPA was simulated in CST-MWS software at the

operating frequency (2 Mhz). Simulated results are in fig. 2 &

fig. 3 as follows. Figure 2 shows the return loss verses

frequency graph and figure 3 shows the radiation pattern ofpatch and its other parameters.

Fig. 2: After Simulation Result of Patch antenna showing ReturnLoss of -13 dB.

Fig. 3: Radiation Pattern of Rectangular microstrip patch antenna

showing directivity of 5.321dBi.

III.(NICOLSON-ROSS-WEIR) APPROACH AND RESPECTEDRESULTS

The considered metamaterial structured design is placed

between the two waveguide ports[6] at the left & right of the

X-Axis as in fig. 5, in respect to calculate the S11 and S21

parameters[7][8]. The signals excitation has been done from

left side to right side of the structure assuming that there is air

in surrounding. The Y-Plane defined as Perfect Electric

Boundary (PEB) and Z-Plane defined as the Perfect Magnetic

Boundary (PMB). Following after, the wave was excited from

the negative X-axis (Port 1) towards the positive X-axis (Port

2).

Fig. 5: Proposed metamaterial structure between the two Waveguide

Ports at the left & right of the X-axis.

Through this arrangement, the S11 and S21 parameters were

exported to Microsoft Excel program for verifying the double-negative metamaterial properties of the proposed metamaterial

structure by using the NRW approach.


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Formulas for calculating the value of permittivity &

permeability using NRW approach [9], [13]:- . (6)

. (7)

Where,

V2 = S21 - S11

= Frequency in Radian,

d = Thickness of the Substrate,

c = Speed of Light,

V2 = Voltage Minima.

The calculated values of permittivity () and permeability

() were calculated by using above equations (6) & (7) in the

simulated frequency range. Graph in fig. 6 & 7 shows that the

resultant metamaterial structure possesses negative values ofpermittivity & permeability at the resonating frequency

Fig. 6: Permittivity versus Frequency Graph obtained from Microsoft

Excel formulation.

Fig. 7: Permeability versus Frequency Graph obtained fromMicrosoft Excel formulation.

RMPA integrated proposed metamaterial structure at aheight 3.276mm from the base plane as shown below in fig. 8.

Fig. 8: Rectangular microstrip patch antennas cover using

metamaterial structure at a height of 3.276mm from the base plane.

The simulated results of the resultant antenna shown below,

by the calculation and simulation it has been found that the

potential parameters like [10] (gain, total efficiency, &

directivity) of the resultant antenna increases significantly incomparison to basic patch antenna alone. Return loss of the

resultant metamaterial structure is reduced by 20dB as shown

in figure 2 & 9 and directivity has been improved by 0.946dBi

(figure 3 & 10).

Fig. 9: Simulated result of proposed metamaterial structure showing

Return Loss of -33dB.

Radiation pattern defined as the power emitted

(transmitted) or accepted (received) by an antenna in a

function of the leaned position and radial distance from the

antenna. It describes how an antenna directs the energy it

radiates and it is resoluted in the farfield region. The fig. 10

below shows the radiation pattern of the proposed metamatrial

structure.

Fig. 10: Radiation Pattern of proposed metamaterial structure anddirectivity of 6.267dBi.

Smith Charts [7] in fig. 11 of the proposed metamaterial

cover antenna shows the impedance matching in the simulated

frequency range.

Fig. 11: Smith chart of proposed metamaterial structure at 2 GHz.


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Figure 12 & 13 are showing the hardware of the proposed

antenna, and Experimental Testing of RMPA along with

designed metamaterial structure respectively, it is being

cleared from figure that the practical result is quite same asthe simulated result from the CST software in operating

frequency range and return loss is significantly reduced after

the implementation of the proposed design of the

metamaterial.

Fig. 12: Fabricated hardware of RMPA superimposed with LHMmetamaterial structure 1.6mm above from the patch.

Fig. 13: Experimental Testing has been done on spectrum analyser of

designed RMPA loaded with metamaterial structure.

Fig. 13: Practically measured result of the proposed RMPA with theimplementation of metamaterial structure showing Return Loss of -23.1dB.

IV.CONCLUSIONThe designed antenna could be used in lots of microwave

applications in L-band (1-2GHz) frequency range that requires

narrow bandwidth, reduced return loss, high directivity &

improved total efficiency at the operating frequency. In fig. 11

the shown smith chart proved that it is matched at the 1.953

GHz frequency, which is matched at the impedance of 50Ohm. The designed metamaterial covered structure improves

the antennas characteristics significantly. The Double

Negative properties of the proposed metamaterial structurehave also been verified using NRW approach. Result achieved

by authors in this letter is tremendous like never before [10],

[16]. Return loss and directivity was improvised to a great

extent, it may improve much better but design got complicated

and will be hard to fabricate. This proposed structure wassimple enough to design, simulate and fabricate and by using

this structured design good result could be achieved.

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COMPACT PATCH ANTENNA PARAMETERS ENHANCEMENT USING LEFT-HANDED METAMATERIAL IN L-BAND

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