Design of a Compact Single Element Dual Band Microstrip Patch Antenna for LTE

Design of a Compact Single Element Dual Band Microstrip Patch Antenna for LTE

Mohammad Rashedul Alam

Dept. of Electronic and Telecommunication Engineering International Islamic university Chittagong(IIUC)

Chittagong, Bangladesh rasel_tushar@yahoo.com Md. Mostafa Amir Faisal

Dept. of Electronic and Telecommunication Engineering International Islamic university Chittagong(IIUC)

Chittagong, Bangladesh

Md. Emran Hossain

Dept. of Electronic and Telecommunication Engineering International Islamic university Chittagong(IIUC)

Chittagong, Bangladesh emranhossain887@gmail.com

oranta68@yahoo.com

Abstract—In today’s modern communication industry, antennas are one of the most necessary elements required to create a communication link. Microstrip antennas have some advantages because of their low profile, light weight and low power handling capacity. A variety of shapes of antennas can be designed to obtain enhanced gain, bandwidth and multiband operation. Designing a compact single element dual band antenna for Long Term Evolution (LTE) frequency bands is a challenge. In this paper, a dual-band E-shaped microstrip antenna for wireless communications in LTE is designed to cover the 1.8 and 3.5 GHz frequency bands. This will allow roaming facilities with LTE compatible devices in large areas like Asia, Europe, Australia, New Zealand etc. Designed antenna is simulated by IE3D (ZELAND) software. The acceptable limit of designed antenna for Return loss is taken to be -7dB or lower.

Index Terms— Microstrip antenna, LTE, dual band, gain.

I. INTRODUCTION

Microstrip patch antennas are popular for their low profile and easy of fabrication by using modern printed circuit technology[1]. These are easy to use in mobile, radio and wireless communication devices because of their lightweight[1]. Long Term Evolution (LTE) is one of the most popular advancements in modern communication Technology.

It is an advanced technology that offers high speed packet access and capacity. The conventional microstrip antennas are limited because of their poor gain, low bandwidth and polarization purity [3]

Due to diversity of usage of frequencies in different regions in this technology, roaming with the same device becomes difficult as antennas used in the devices does not always support frequency bands in the roaming places [5]. So, to overcome the problem, incorporating more antennas in a device is necessary to resonate at different frequencies, which

make the device size bigger. Research is going on to incorporate more frequency bands in a single antenna so that it takes lesser space and help make the device smaller.

One of the most popular ways to incorporate more frequency bands in a single element has been to cut slots of different shapes on a fundamental geometry. An antenna is to cover 750-960 MHz and 1700-2700 MHz is proposed in [6].

Multiband MIMO antenna for LTE operation to operate at LTE band 13 and LTE band 7 was designed in [7]. Another antenna to operate at bands 0.5–0.75, 1.1–2.7, 3.3–3.9 GHz was designed in [8]. Similarly many more researches incorporating many bands in a single geometry has been going on recently [9] [10] [11].

A compact single element dual band antenna covering LTE FDD bands 2 and 22 and the most popular LTE TDD band 42 has been proposed in this work. These frequencies are in action in different regions of the world which would allow designers to make the devices compatible with LTE to roam in those regions without making the device size bigger.

For practical use, gain with respect to return loss of -7dB is acceptable. As this work is based on simulation, return loss of - 10dB, which corresponds to VSWR of 2, is taken to be minimum.

II. ANTENNA CONFIGURATION

The proposed antenna geometry is shown in Fig.1. Firstly, the antenna is fabricated on a 60 mil RT/duroid 5880LZ substrate from Rogers-Corp with the dielectric constant of 2.2 and loss tangent of 0.002.The thickness is h1=h2=1.575mm.

Dimensions of the ground plane are also 100*100 mm². As shown in Fig. 1, the radiating element is a coaxial probe feed antenna with an E-shaped slot. For achieving the dual band operation, we used multi-slots on that E-shaped antenna.

The size of the coaxial probe feed patch antenna is associated with the first resonant frequency and the second resonant frequency is associated with the E-shaped slot parameters. The other parameters in Fig. 1 (wt,w1,w2,w3,w4) are used to achieve International Conference on Materials, Electronics & Information Engineering, ICMEIE-2015

05-06 June, 2015, Faculty of Engineering, University of Rajshahi, Bangladesh www.ru.ac.bd/icmeie2015/proceedings/

ISBN 978-984-33-8940--4

good impedance matching at both resonant frequencies. For obtaining two resonant frequencies at 1.8GHz and 3.5 GHz, optimum values of the structural parameters of the proposed antenna are in Table 1.

TABLE I. PARAMETER OF PROPOSED ANTENNA

Design of dual band Microstrip Patch Antenna Total Width of the Patch(Wt) 53mm Effective dielectric constant of

the patch( )

2.2 Total Length of the patch(Lt) 55.5mm Input Resistance of the patch 50Ω Width of the patch (W1) 37mm Width of the patch (W2) 15mm Width of the patch(W3=W4) 4mm Inset depth of the patch (y0) 12mm Length of the patch(L1) 35mm Length of the patch(L2) 20.5mm Length of the slot(S1) 14mm Length of the slot(S2) 3.5mm Width of the slot(S1=S2) 1mm

F ig:1,Geometry of Proposed dual band antenna.

III. RESULTS AND SIMULATION A. Return Loss

The simulated and experimental results of the antenna return loss are shown in Figure 2. The experimental values of the first and second resonant frequencies are 1.8GHz and 3.5GHz which are shown in figure. In accordance with results

shown in Fig. 2 the resonant frequencies can be calculated approximately as follows:

f

1= ………..(1)

f

2= ………(2)

where L1 and L2 are the average lengths for current paths of the 1st and 2nd resonant modes and c is the free space velocity of light. The resonance frequencies are calculated by equating its area to an equivalent area of a rectangular microstrip patch antenna. From geometry the average lengths of current paths for the 1st and 2nd resonant modes are obtained as L1 = 35mm and L2 = 20.5mm. Thus “Equation 1”

and “Equation 2” give the resonant frequencies of 1.8GHz and 3.5GHz respectively.

Fig:2 Return loss for the two Resonant modes of the Antenna.

The first part of the impedance matching procedure is to produce equal value of input impedance at both resonant frequencies. The second part of impedance matching is achieved by varying W3.The final stage in the design process involves the use of an inset feed. It is found that the impedance at both frequency match to 50Ω. The bandwidths calculated at - 10dB at 1.8GHz and 3.5GHz are 32.2MHz and 59.8MHz respectively.

B. Gain And Efficiency

The simulated patch antenna has given resonant frequencies of 1.8 and 3.5 GHz. It can be observed from fig 2 that useful return loss peaks of the dual band patch antenna at 1.8GHz and 3.5 GHz are –20.68 dB and -21.72 dB respectively.

International Conference on Materials, Electronics & Information Engineering, ICMEIE-2015 05-06 June, 2015, Faculty of Engineering, University of Rajshahi, Bangladesh

www.ru.ac.bd/icmeie2015/proceedings/

ISBN 978-984-33-8940--4

C. Radiation Pattern

Figure 3 shows the measured co-polarization and cross- polarization radiation patterns for both resonant modes.

Fig:3(a) 2D Radiation Pattern of 1.8GHz

Fig:3(b) 2D Radiation Pattern of 3.5GHz

From the figures 3(a, b) we can see that the radiation patterns of the proposed microstrip antenna is in conformity with the normal radiation pattern of microstrip antennas. So the design is suitable for using in applications where other microstrip antennas are used.

D. Parametric Analysis

As stated earlier, antenna dimensions have been found using empirical expressions from [8]. To keep the design simple, the parameters are rounded up to the nearest integers..

Now we are going to observe and comment on the return loss found for the change of the antenna parameters W and L.

First W is changed to higher value.

TABLE II. CHANGING OF W

The width W is increased from 53 mm to 55 mm to see the effect on the frequency response in table II. As the W is increased from 53mm, the resonant frequency shifts to its right and the return loss also decreases. Both of them are unwanted scenarios. So now we should decrease W from 53mm and it shows that resonant frequency shifts to its left and return loss keeps decreasing. So 53mm is the perfect choice in this case.

TABLE III. CHANGING OF L Length

of the Patch(L)

Bandwidth(dB)

Remarks

1.8GHz

3.5GHz

Direction Bandwidth 53.5mm -11.56 -22.41 Rightward Decreases 54.5mm -10.20 -19.63 Rightward Decreases 55.5mm -20.64 -20.50 Exact Maximum 56.5mm -11.52 -17.04 Leftward Decreases 57.5mm -15.44 -14.95 Leftward Decreases The Length L is decreased from 55.5 mm to 53.5 mm to see the effect on the frequency response in table III.As the L is Decreased from 55.5 mm, the resonant frequency shifs to its right and the return loss also degrades. Now W is increased from 55.5mm and it shows that resonant frequency shifts to its left but return loss also keeps degrading.

As resonance frequency of this antenna does not improve by changing of Length (L) and Width (W) of the patch, desired criterion is best achieved when width is 53mm and length is 55.5mm.

Width of the Patch(W)

Bandwidth(dB) Remarks

1.8GHz 3.5GHz Direction Bandwidth 55mm -19.4 -19.22 Rightward Decreases 54mm -20.20 -18.72 Rightward Decreases

53mm -20.68 -21.72 Exact Maximum

52mm -17.03 -18.52 Leftward Decreases 51mm -18.82 -14.45 Leftward Decreases International Conference on Materials, Electronics & Information Engineering, ICMEIE-2015

05-06 June, 2015, Faculty of Engineering, University of Rajshahi, Bangladesh www.ru.ac.bd/icmeie2015/proceedings/

ISBN 978-984-33-8940--4

IV. CONCLUSION

The use of MOM based simulation software (IE3D) is demonstrated to design a dual-band rectangular microstrip antenna for LTE applications. In this paper a multi-slot patch antenna is proposed for dual frequency applications. The simulation shows operation at 1.8 GHz and 3.5 GHz with consistency in radiation patterns. The reflection co-efficient is below −10dB from 1.788 to 1.814GHz for 1.8GHz and 3.48 to 3.54GHz for 3.5GHz. The concept can be simply adapted to design other antennas operating at different frequency band.

ACKNOWLEDGMENT

All praises to Almighty Allah, Whose enormous blessings have given us strength and made us able to complete this paper.

We would like to express our gratitude to our kind supervisor Mostafa Amir Faisal for his guidance, support and encouragement. Working with him has been a true privilege and great experience for us. His guidance and advice has been a great source of inspiration for us throughout the paper work.

Finally, all blessings upon our beloved parents, families and friends whose prayers and moral support always motivated us to complete our studies.

REFERENCES

[1] C. A. Balanis, “Antenna Theory, Analysis and Design,” John Wiley & Sons, New York, 1997.

[2] Howell, J., "Microstrip antennas," Antennas and Propagation, IEEE Transactions on, vol.23, no.1, pp.90,93, Jan 1975

[3] Narang Tanisha; Jain Shubhangi, "Microstrip Patch Antenna-A Historical Perspective of the Development," Advances in Communication and Control Systems 2013 (CAC2S 2013) [4] Releases 8-12; http://www.3gpp.org/

[5] http://en.wikipedia.org/wiki/List_of_LTE_networks

[6] Shuai Zhang; Kun Zhao; Zhinong Ying; Sailing He, "Adaptive Quad-Element Multi-Wideband Antenna Array for User- Effective LTE MIMO Mobile Terminals," Antennas and Propagation, IEEE Transactions on , vol.61, no.8, pp.4275,4283, Aug. 2013

[7] Lu Zhang; Yan Shi; Long Li; Chang-Hong Liang, "Multiband MIMO antenna for wireless USB dongle in LTE operation," Microwave and Millimeter Wave Circuits and System Technology (MMWCST), 2013 International Workshop on , vol., no., pp.40,43, 24-25 Oct. 2013

[8] Elamin, N.IM.; Rahman, T.A; Abdulrahman, AY., "New Adjustable Slot Meander Patch Antenna for 4G Handheld Devices," Antennas and Wireless Propagation Letters, IEEE , vol.12, no., pp.1077,1080, 2013

[9] Kulkarni, AN.; Sharma, S.K., "A compact multiband antenna with MIMO implementation for USB size 4G LTE wireless devices," Antennas and Propagation (APSURSI), 2011 IEEE International Symposium on , vol., no., pp.2215,2218, 3-8 July 2011

[10] Woo Kyoung Lee; Myun-Joo Park; Young-seek Chung;

Byeongkwan Kim; Hyunho Wi; Byungje Lee; Chang-Won Jung, "Multiband LTE MIMO antenna for laptop applications," Antennas and Propagation (APSURSI), 2011 IEEE International Symposium on , vol., no., pp.1354,1356, 3-8 July 2011

[11] Mun, B.; Jung, C.; Park, M.-J.; Lee, B., "A Compact Frequency- Reconfigurable Multiband LTE MIMO Antenna for Laptop Applications," Antennas and Wireless Propagation Letters, IEEE , vol.13, no., pp.1389,1392, 2014.

International Conference on Materials, Electronics & Information Engineering, ICMEIE-2015 05-06 June, 2015, Faculty of Engineering, University of Rajshahi, Bangladesh

www.ru.ac.bd/icmeie2015/proceedings/

ISBN 978-984-33-8940--4