U Slot Antenna

U-Slot Multiband Inkjet Printed Antenna 1 inkjet Abstract— thick copper sheet Realization of U-slot tri-band Monopole antenna on a low cost paper substrate using inkjet printed technology is presented for the first time. U-shaped slot is optimized to enhance the bandwidth and to achieve tri-band operation of 1.57, 3.2. U- SLOTS ANTENNA DESIGN Four band linear polarization asymmetrical U slot patch antenna’s geometry is shown in figure 1.In ground plane under the patch, a square copper plate was used along its edge having length L=50 mm. Air is used as substrate and coaxial probe is connected directly to the patch. Inner and outer. Dual-broadband antenna elements, each of which comprises. Two opened loops, an outer loop and an inner loop. Two U-(0.258)(+0.8) shaped slots are etched to reduce the coupling between the two dual-broadband antenna elements.

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International Journal of Scientific & Engineering Research, Volume Ś, Issue ŝ, ž•¢-201ř

ISSN 2229-5518

1469

Design & Simulation of Double U-Slot Microstrip

Patch Antenna for WiMAX Application

Md. Suaibur Rahman1, Md. Munjure Mowla2, Md. Mahabub Alam3

Abstract— This paper presents the numerical simulation of double U-slots microstrip patch antenna for W iMAX application. The proposed antenna is feed by the Transmission line. The total area occupies by the antenna 40mmx47mm. In this design two slots and one bridge ele ments have been ap- plied to generate the three frequencies bands 2.44GHz, 3.26GHz and 5.38GHz respectively. In addition, the antenna has achievable return l oss, radia- tion pattern and also bandwidths within the -8dB return loss bandwidth. The bandwidths of the three frequencies band are 4.22%, 1.87% and 3.51%

respectively. The return loss S11 characteristic for the three band are -24dB, -20dB and -47dB respectively. Due to the compact area occupied, the pro- posed antenna is promising to be embedded within the different portable devices employing W iMAX applications.

Index Terms— Patch antenna, Double U-slot antenna, W iMAX antenna, GEMS software simulink.

——————————  ——————————
microstrip antenna consists of a dielectric substrate, with a ground plane on the other side. The microstrip patch antenna is very well suited for applications such as wireless communication system, cellular phone, radar system and sa- tellite communication system [1], [2]. The IEEE 802.16 working group has established a new standard known as WiMAX (Worldwide Interoperability for Microwave Access) which can reach a theoretical up to 30- mile radius coverage. Moreover, in the case of WiMAX, the highest theoretically achievable transmission rates are possible at 70 Mbps. One of the poten- tial applications of WiMAX is to provide backhaul support for mobile WiFi hotspots. A low profile double U-slots antenna for WiMAX operation has low return loss and bandwidth. Recently, proposed printed antenna for WiMAX operation has the three frequencies bands but the return loss not over -30dB [3]. The broadband characteristic of a microstrip patch antenna with U-shaped slot has been confirmed by many published results [4], [5]. Also, several designs of broadband slots anten- na have been reported [6], [7]. A monopole antenna for Wi- MAX applications was proposed in [8]. In this paper, two slots and one bridge elements have been applied to generate the three frequencies bands to be used in WiMAX technology. Basically WiMAX has three allocated frequency bands called low band, middle band and high band. The low band has fre-

————————————————

 Md. Suaibur Rahman is with the Electronics and Telecommunication Engi- neering Department in Rajshahi University of Engineering & Technology (RUET), Rajshahi-6204, Bangladesh. (Corresponding author to provide phone:

+88-01723644003; e-mail: suaiburruet@gmail.com).

 Md. Munjure Mowla is with the Electronics and Telecommunication Engi-

neering Department in Rajshahi University of Engineering & Technology

(RUET), Rajshahi-6204, Bangladesh. (E-mail: rimonece@yahoo.com).

 Md. Mahabub Alam is with the Electronics and Telecommunication Engineer-

ing Department in Rajshahi University of Engineering & Technology (RUET),

Rajshahi-6204, Bangladesh. (E-mail: mahbub.ete@gmail.com).

quency from 2.4 GHz to 2.8 GHz, the middle band has fre- quency from 3.2 GHz to 3.8 GHz and the high band has
5.2GHz to 5.8 GHz. This paper addresses the numerical analy- sis of the proposed antenna for WiMAX operation with ac- ceptable return loss, gain and bandwidth. For the numerical analysis we consider the substrate permittivity of the antenna is r =4.4(FR4) with substrate thickness 1.2mm and feed by a 50
Ω microstrip line. The analysis is performed numerically using
GEMS software.
The paper is divided as follow: Section 2 discusses the antenna design and structure; Section 3 presents the parameter study; Section 4 explains the simulation process for the antenna and Section 5 conclusions.

In this paper several parameter have been investigate using GEMS software. The design specifications for the patch anten- na are:
 The dielectric material selected for the design is FR4.
 Dielectric constant 4.4
 Height of substrate (h) = 1.2 mm.
The antenna is fed by 50 Ω microstrip line, the main advantage of using transmission line feeding is very easy to fabricate and simple to match by controlling the inset position and relatively simple to model [3]. The proposed antenna has two U-slot shaped and one bridge to connect both shapes together as shown in Fig.1, the detailed dimensions are given in Table-1.

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International Journal of Scientific & Engineering Research Volume Śǰȱ œœžŽȱŝǰȱ ž•¢ȬŘŖŗřȱ

ISSN 2229-5518

1470

3.1 The effect of changing width of W

In Fig.3, it shows the return loss based on variation in the width of the second U-slot (W) from 30 mm to 35 mm and to
40 mm. The first and second bands are not affected by the width of the second U-slot.

U Slot Antenna

Changing the width (w)

0

-10

-20

-30

-40

-50

w=30 w=35 w=40

2 2.5 3 3.5 4 4.5 5 5.5

Fig.1 The geometric view of the proposed patch antenna

Frequency (GHz)

Fig.3 The effect of the increasing the width of W

9

x 10

The proposed antenna generates three bands at 2.44, 3.23 and
5.38 GHz with simulated impedance bandwidth of 4.22%,

TABLE 1

THE DIMENSION OF THE U-SLOTS ANTENNA (UNIT=MM)

1.87% and 3.51% respectively. Thus the three bands satisfied the required bandwidth for the WiMAX compliant transmit- ters.

S-parameter

0

-5

When 30mm width is used then first band and second band return loss increasing but third band decreasing. Again when we are used 40mm width then first band and third band re- turn loss increasing but second band decreased and band- width also decreasing. Finally, when we are sued 35mm width then three band return loss and bandwidth increasing. The good characteristic of the return loss and the bandwidth is obtained (W) 35 mm.

3.2 The of changing width of bridge C2

In Fig.4, it is describes the return loss based on increasing and decreasing the width (C2) of the first U-slot. Bridge width af- fects the bandwidth of the resonance frequency and return loss. When bridge width is sued 2.5mm then return loss is in- creased but bandwidth is decreased. When bridge width is

-10

-15

-20

-25

-30

-35

-40

-45

Excitation/ S-parameter

sued 4mm then bandwidth is increased but return loss is de- creased. Again, when we are used bridge width 3mm then return loss and bandwidth also increased. The good characte- ristic of the return loss and the bandwidth is obtained (C2) 3 mm.

Changing width of Bridge (C2)

0

2 2.5 3 3.5 4 4.5 5 5.5

-10

Frequency(GHz)

Fig.2 The return loss simulation result with two U-slots

9

x 10

-20

C2= 2.5 mm

C2=3 mm

C2=4 mm

As show in Fib.2 the simulation indicates a response at 2.44
GHz with return loss = - 24 dB, 3.26GHz with return loss = -20
dB and 5.38 GHz with return loss = -47 dB. The bandwidths of
the dual band are 4.22 %, 1.87% and 3.51 % respectively.

-30

-40

-50

2 2.5 3 3.5 4 4.5 5 5.5

There are some parameter that effect the antenna performance,

Frequency(GHz)

Fig.4 The effect of increasing the width of bridge (C2)

9

x 10

two of them have a very noticeable effect in the determining the performance of the antenna. The two parameters that
show the most effect are width of the W and width of the bridge. The return losses are different according to parameter changes. These effects will be explained and summarized in this section.
The radiation patterns at the centre frequencies 2.44GHz,
3.26GHz and 5.38GHz of WiMAX application are plotted as
shown in Fig.5 (a)-(c). The 3D radiation pattern at the center
frequencies 2.44GHz, 3.26GHz and 5.38GHz are plotted as
shown in Fug.6 (a)-(c).

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International Journal of Scientific & Engineering Research Volume Śǰȱ œœžŽȱŝǰȱ ž•¢ȬŘŖŗřȱ

ISSN 2229-5518

Fig.5 (a) Radiation pattern E-plane and H-plane at 2.44GHz

Fig.5 (b) Radiation pattern E-plane and H-plane at 3.26 GHz

Fig.5 (c) Radiation pattern E-plane and H-plane at 5.38 GHz

U Slot Antenna Booster

1471

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Fig.6 (a) 3D Radiation pattern at 2.44GHz Fig.6 (b) 3D Radiation pattern at 3.26 GHz Fig.6 (c) 3D Radiation pattern at 5.38 GHz

tively. The U- slot patch antenna is designed for increasing the bandwidth and return loss but gain cannot increase. If array of the U- slot patch antenna is used then the gain can be im- proved. Therefore, the antenna will be better work in the Wi- MAX applications and wireless communications system.

REFERENCES

[1] W.L. Stutzman and G.A. Thiele, Antenna Theory and Design, 2nd ed.

New York: Wiley, 1998.

[2] C.A. Balanis, Antenna Theory, 2nd Ed. New York: John Wiley & sons, Inc., 1997.

[3] Hattan F. Abu Tarboush, D. Budimir, R. Nilavalan “Connected U - slots Patch Antenna for WiMAX Applications”. International Journal of RF & Microwave CAF, 2008.

[4] H. F. AbuTarboush, H. S. Al-Raweshidy, “A Connected E-Shape and U-Shape Dual- Band Patch Antenna for Different Wireless Applica- tions”, the Second International EURASIP Workshop on RFID Tech- nology, July, 2008.

[5] M. Sanad, “Double C-patch antennas having different aperture shapes,” in Proc. IEEE Antennas and Propagation Dig., June 1995, pp.2116–2119.

[6] Murad NA. “Microstrip U-shaped dual-band antenna,” Applied

Electromagnetic, 2005 APACE 2005 Asia-Pacific Conference on

2005:4 pp

[7] Hadian AM. “Wideband rectangular microstrip patch antenna with U-slot,” Antennas and Propagation, 2007 EuCAP 2007 The Second European Conference on. 2007:1-5.

[8] T. liu and L. L. Wong, “A wideband Stubby Monopole Antenna and a GPS for WiMAX Mobile Phone with E911 Function,” Microwave and Optical Technology Letter, Vol 46, 2005, pp. 485-487.

This paper presented the simulation of the maicrostrip patch antenna with double U-slots. From two U- slots shape on the patch, the three bands can be generated and by adding one bridge the exact frequencies band for WiMAX can be achieved. The three frequency band 2.44GHz, 3.26GHz and 5.38GHz has been achieved as well as the bandwidth requirements for Wi- MAX standards 4.22%, 1.87% and 3.51% respectively. The re- turn loss for the triple band are -24dB, -20dB and -47dB respec-

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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

U Slot Antenna Cable

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