Microstrip Patch Antennas (or simply patch antenna) are increasingly useful because the antenna is printed directly onto a circuit board. Additional benefits of patch antennas is that they are easily fabricated making them cost effective. Their low profile design, often square or rectangular, allows them to be mounted to flat surfaces. Slots and Notch Loaded Rectangular Stacked Microstrip Antenna for Multiband Operations www.ijceronline.com Open Access Journal Page 65 substrate with dielectric constant of 4.8 and loss tangent of 0.3045 cf. Both the patches have same.

1. Microstrip Antenna Hfss
2. Microstrip Antenna Design Handbook

International Journal of Scientific & Engineering Research, Volume 5, Issue 6, June-2014 1469

ISSN 2229-5518

Sujeet Kumar Yadav, Kirti Vyas, Sudarshan Kumar

Abstract- Here in this paper a compact microstrip antenna having wide-slots of hexagon shape is fed by microstrip-line for wideband and multi band operations is proposed and studied. The proposed antenna resonates the 10-dB bandwidth from 0 to 6.0 GHz, and these frequency bands cover the standard IEEE 802.11b/g (2.4-2.485 GHz) and IEEE 802.11a (5.15-5.35 GHz) for WLAN applications and 2.5

GHz (2.5-2.69 GHz), 3.5 GHz (3.3-3.8 GHz) and 5 GHz (5.25-5.85 GHz) for Wi -MAX applications. Detailed design and experimental

results are shown and discussed in this paper. The antenna is simulated using IE3D electromagnetic simulator. Here in this paper the improvement in multiband and wide band behavior is investigated & discussed with VSWR<2.

Index Terms- IE3D, Microstrip line, Microstrip Slot Antenna (MSA), Multiband, Resonant Frequency.

——————————  ——————————

I. INTRODUCTION

Microstrip patch antennas are low profile, conformable to planar and non planar surfaces, simple and less expensive in manufacturing using modern printed circuit technology. The main objective in the wireless communication system is the design of wideband or even multiband low profile and small antenna. One such antenna that meets these requirements is the slot Antenna [1]. There are numerous techniques such as shorting pins, introducing slots and fractal geometries that reduce the size of the patch antenna. Micro strip slot antennas (MSAs) have the advantages of being able to produce bidirectional and unidirectional radiation patterns with larger bandwidth and very low cross polarization (typically -35dB) as compared to microstrip patch antenna [2]. In, Microstrip slot antenna, the strip and slot combination offer an additional degree of freedom in the design of microstrip antennas. A microstrip slot antenna comprises a slot cut in the ground plane of the micro strip line such that the slot is perpendicular to the strip conductor of the microstrip line .The field of the microstrip line excite the slot. For efficient excitation of the slot the strip conductor is either short circuited through the dielectric substrate to the edge of the slot, as shown in figure (a) or the strip conductor is terminated in
an open circuited stub beyond the edge of the slot, as
shown in figure (b) [3].
Figure 1 (b). Figure 1 (a)

Centre- fed micro strip slot antenna configurations: (a) Micro strip terminated in a short circuited- stub (b) Micro strip terminated in an open circuited- stub

The regular MSA configurations, such as rectangular and
circular patches can be modified to rectangular and circular ring, respectively, to enhance the BW. The larger BW is because of a reduction in the quality factor Q of the
patch resonator, which is due to less energy stored

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beneath the patch and higher radiation. When a U-shaped slot is cut inside the rectangular patch, it gives a BW of approximately 40% for VSWR <2. Similar results are
obtained when a U-slot is cut inside a circular or a
28mm and the width is 38mm. The dimensions of the patch are calculated according the given formula as shown below.
triangular MSA [4]. But as the Antenna size reduces, its parameters such as gain, efficiency and polarization
deteriorates. This occurs due to the impedance

𝑊 =

𝑐

2𝑓0

2

�

𝜀𝑟 + 1

(1)

mismatching that occurs between the source and the

𝜀𝑟𝑒𝑓𝑓 =

(𝜀𝑟+1)

2

+ (𝜀𝑟−1)

2

(1 +

12ℎ

𝑤

)−� �2� (2)

antenna. Microstrip slot antennas have numerous promising features but they suffer from undesired modes

𝐿 = 𝑐

𝑒𝑓𝑓 2𝑓0� 𝜀𝑟𝑒𝑓𝑓

(3)

𝑤

such as the parallel plate mode excited between the
ground planes of the strip line. One additional drawback

∆𝐿 = 0.412ℎ

Microstrip Antenna Hfss

� 𝜀𝑟𝑒𝑓𝑓 + 0.3�( ℎ + 0.264)

� 𝜀 − 0.258�(𝑤 + 0.8)

(4)

is it’s inherently bidirectional radiation which can be corrected by using a metallic cavity or a metallic reflector on one side. This antenna works on various frequencies between 0 GHz to 6 GHz, which includes the applications in WLAN, Satellite mobile communication & Wi-Max [5]- [6].

II. ANTENNA DESIGN

The proposed antenna is simulated and designed on the Glass-Epoxy/FR4 substrate. The relative dielectric constant of the FR4 is 4.4 and loss tangent is 0.02, although the loss tangent of the FR4 is high but it is less expensive and easily available. The dimension of the rectangular patch is calculated at the resonance frequency at 2.4 GHz. The length of the patch is

𝐿 = 𝐿𝑒𝑓𝑓 − 2∆𝐿 (5)

c = Velocity of light in free space
f 0 =Operating resonant frequency
ɛr = Relative dielectric constant
ɛreff =Effective dielectric constant of the substrate
h= Height of the substrate w = Width of the substrate
The three structure of the patch antenna is designed. One
is simple rectangular patch of given dimension, another one with a rectangular patch with a single hexagonal slot
,the dimension of the hexagon is 10mm and the third
structure is rectangular patch with five hexagon slots, in which one hexagon has the same dimensions as in second structure and another four hexagons have dimensions of
10/3mm each. These four slots are symmetrically located
at the coordinates at (9, 12), (9,-12), (-9, 12) and (-9,-
12).The feeding techniques use in all the structures is the microstrip line feeding .The microstrip line has the dimensions of 3x10mm.In all the structures the microstrip
line is at the same distance from the radiating edge of the
patch antenna[7]. Structures of the proposed work are shown below.

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III. SIMULATION RESULTS & DISCUSSION
(a) (b)

(c)

Fig 2: Antenna Design (a) zero slot (b)

single slot (c) five slots

The third design of antenna is fabricated and tested the simulated results related to this design. The photo of fabricated antenna is shown below.

Fig 3: Microstrip path antenna having with hexagon slot With all these designs the resulted resonance frequencies are as listed below.

TABLE 1: Antenna designs and observed resonance

frequencies

The proposed antenna is simulated over Integral
Equation in 3 Dimension (IE3D) software as simulation tool. Characteristics of a hexagonal shape Microstrip patch antenna for wideband and multiband applications have been analyzed in term of various parameters like return loss, Total Field Gain, Directivity, Radiation pattern & VSWR etc. Multiband behavior is achieved at frequency of 2.4GHz, second band is at 3.7 GHz and third band is obtained at 5.3 GHz frequency for Microstrip antenna designed for 2.4 GHz with no slots[8]-[9]. Following are the various results obtained for the above mentioned design

[A] Return Loss curve:

Figure (4) (i) Return loss for antenna ‘a’

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Figure (4) (ii) Return loss for antenna ‘b’

Figure (4) (iii) Return loss for antenna ‘c’

[b] Comparison between simulated and measured result for antenna having five slots

Figure (5)

[c] Total Field gain vs. Frequency curve

Figure (6) (Total Field Gain vs. Frequency For zero, single and five slots)

Black curve ---- zero slot Violet curve --- single slot

Green curve --- Five slots

0

R

E -5

T -10

U -15

R

N -20

L -25

O -30

S

S -35

Microstrip Antenna Design Handbook

-40

FREQUENCY(GHz)

0 2 4 6 8

SIMULATED MESURED

[d] Total Field Directivity vs. Frequency curve:

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Figure (7)

(Total Field Directivity Vs Frequency For 0, 1 & 5

hexagonal slots)

[e] VSWR curve:

Figure (8) (i) VSWR for antenna ‘a’
Figure (8) (ii) VSWR for antenna ‘b’
Figure (8) (iii) VSWR for antenna ‘c’ [f] Radiation Pattern Curve:

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(3D Radiation pattern for zero slots at 5.39 GHz)

Figure (9) ( i)
Figure (9) ( ii)

(3D Radiation pattern for single slot at 4.26 GHz)

Figure (9) ( iii)

(3D Radiation pattern for iteration 2 at 5.32 GHz)

VI. CONCLUSION
In this work three structure of rectangular patch antenna is studied. Three structure of patch antenna with zero slot, single hexagon slot and five hexagon slots are simulated and the geometry with five slots is fabricated.
As the number of slots increased, the bandwidth is increased [10]-[11]-[12]. These antennas are used in IEEE
802.11 a, b, g, and Wi-Max applications [13]. In addition, the proposed antennas also have simplicity in structure, compact size and good radiation performances [14]-[15].
REFERENCES
[1] Constantine A. Balanis, “Antenna Theory-Analysis and Design”, John Villey & Son, INC, Third Edition 1995.
[2] Axelrod A.M Kisliuk, and JMaoz, “Broadband
Microstrip-Fed Slot Radiator”, Microwave Journal, June
1989, pp.81-94.
[3]Bahl, I., P.Bhartia, and R. Garg, Microstrip Antenna

Design Handbook, Artech House, 2001.

[4] Girish Kumar, K.P Ray, “Broadband Microstrip
Antennas”, Artech House, London. Edition 2003.
[5]Wi-MAXForum, http://www.wimaxforum.org/home/, last visited on May 10, 2014.
[6] Ritosa P. , T. Korosec, J. Tratnik, L. Naglic, and B. Batagelj,Adaptive Wi-MAX subscriber antenna for 2.6
GHz and 3.45 GHz,' EUROCON 2009, 46-51, St. Petersburg, Russia,May 2009.
[7] Ray, K. P., D. M. Suple and N. Kant, “Perturbed
Hexagonal Microstrip Antenna for Circular Polarization,”

IEEE, 978-1-4244-4819-7/09, 2009.

[8] Ghaderi, M.R., Mohajeri, F., “A Compact Hexagonal Wide-Slot Antenna with Microstrip-Fed Monopole for UWB Application”, Antennas and Wireless Propagation Letters, IEEE, Volume 10, June 2011, pp 682 – 685.
[9] H. Sabri and Z. Atlasbaf, “Two Novel Compact Triple- Band Microstrip Annular-Ring Slot Antenna For PCS-
1900and WLAN Applications”, Progress In

Electromagnetics Research Letters, Vol. 5, 87–98, and 2008.

[10] Werner, D. H. and R. Mittra, Frontiers in

Electromagnetics, IEEE Press, New York, 2000.

[11] K. Nithisopa1, J. Nakasuwan1, N. Songthanapitak, N. Anantrasirichai, and T. Wakabayashi, “Design CPW
Fed Slot Antenna for Wideband Applications” PIERS ONLINE, VOL. 3, NO. 7, 2007, pp 1124-1127.

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[12] Y.Sung,”Bandwidth Enhancement of a Microstrip Line-Fed Printed Wide –Slot Antenna with a Parasitic Centre Patch”,IEEE Transactions on Antennas & Propagation,Vol. 60,No. 4,April 2012,pp 1712-1716.
[13] W.S.Chen,B.Y Lee,P.Y Chang, “A compact microstrip- line- fed slot antenna with dual band notched for Wi-Max operation,' PIER, Vol. 16, 13-23, 2010.
[14] Mohammad A. Dorostkar, Mohammad T. Islam, and
Rezaul Azim, “design of a novel super wideband circular
hexagonal fractal antenna” Progress In Electromagnetics

Research, Vol. 139, 229-245, 2013

[15] C.J. Wang, S.W. Chang, “Studies on Dual-Band
Multi-Slot Antennas”, Progress in Electromagnetics

Research, PIER 83, 293–306, 2008

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• Antenna Theory Tutorial

• Antenna Basic Terms

• Types of Antennas

• Antenna Arrays

• Wave Propagation

• Antenna Theory Useful Resources

• Selected Reading

Slot Antenna is an example of Aperture antenna. A rectangular slot is made on the conducting sheet. These slot antennas can be formed by simply making a cut on the surface, where they are mounted on.

Frequency Range

The frequency range used for the application of Slot antenna is 300 MHz to 30 GHz. It works in UHF and SHF frequency ranges.

Construction & Working of Slot Antennas

The use of slot antennas is well understood through its working principle. Let us have a look at the structure of a slot antenna.

When an infinite conducting sheet is made a rectangular cut and the fields are excited in the aperture (which is called as a slot), it is termed as Slot antenna. This can be understood by observing the image of a slot antenna. The following image shows the model of a Slot antenna.

The working of Slot Antenna can be easily understood through Babinet’s principle of optics. This concept gives an introduction to the slot antennas.

Babinet’s Principle

Babinet’s principle states that- “When the field behind a screen with an opening is added to the field of a complementary structure, the sum is equal to the field when there is no screen”.

The above images clearly explain the principle. In all the regions, which are non-collinear with the beam, the above two screens, in figures 1 & 2, produce the same diffraction pattern.

Case 1 − Consider a light source and a conducting plane (field) with an aperture before a screen. The light does not pass through the opaque area, but passes through the aperture.

Case 2 − Consider the light source and a conducting plane of the size of the aperture in the previous case, being held against the screen. The light does not pass through the plane but through the remaining portion.

Case 3 − Combine these two conducting planes of both the cases and put before the light source. The screen is not placed to observe the resultant combination. The effect of screen gets nullified.

Working of Slot Antenna

This principle of optics is applied to electromagnetic waves for the wave to get radiated. It is true that when a HF field exists across a narrow slot in a conducting plane, the energy is radiated.

The image shows a slot antenna, which explains well about its working.

Consider an infinite plane conducting screen is taken and pierced with apertures of desired shape and size and this will be the screen of slot antenna. Another screen is considered interchanging the places of aperture and screen area which is the complementary screen.

These two screens are said to be complementary as they result in complete infinte metal screen. Now, this becomes the slot antenna. The terminal impedance is quite desirable for the radiation.

Radiation Pattern

The radiation pattern of the Slot antenna is Omni-directional, just like a half-wave dipole antenna. Take a look at the following illustration. It shows the radiation pattern of Slot antenna drawn in Horizontal and Vertical planes respectively

Advantages

The following are the advantages of Slot antenna −

• It can be fabricated and concealed within metallic objects
• It can provide covert communications with a small transmitter

Disadvantages

The following are the disadvantages of Slot antenna −

• Higher cross-polarization levels
• Lower radiation efficiency

Applications

The following are the applications of Slot antenna −

• Usually for radar navigational purposes
• Used as an array fed by a wave guide