The antenna has be designed using High Frequency Substrate Simulator Software (13.0 version). On simulation it could be
IJRIT International Journal of Research in Information Technology, Volume 2, Issue 5, May 2014, Pg: 179-185
International Journal of Research in Information Technology (IJRIT)
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Design and Simulation of Multi-Band Microstrip Patch Antenna For Wireless Communication Misha Thakur1, Er. Gaurav Walia2, Dr. Kuldip Pahwa3 1 M.Tech Final Year Student, Deptt. of ECE, MMEC, MMU, Mullana, Ambala, Haryana, India
[email protected] 2 Assistant Professor, Deptt. of ECE, Ambala College of Engineering and Applied Research, Mithapur Ambala Haryana, India
[email protected] 3 Head of the Deptt. of ECE, MMEC, MMU, Mullana, Ambala Haryana, India
[email protected] Abstract This paper presents an approach to design and simulate a multi-band microstrip patch antenna with co-axial feed, for Wireless applications. The antenna is a combination of a triangular patch and a rectangular patch to be functional over 2.4 GHz frequency. The rectangular patch is engraved with slots cut into it for multi-band operations. The antenna has be designed using High Frequency Substrate Simulator Software (13.0 version). On simulation it could be seen that the antenna was resonant on multiple frequencies where it had good return loss and acceptable VSWR. This antenna can be used for several applications, especially in GSM domain, Wi-Fi, Bluetooth, and several other papers detailed in the paper.
Keywords – Microstrip antenna, Multi-band, Wi-Fi , WLAN, narrowband, HFSS.
1.
INTRODUCTION
A patch antenna is a narrowband, wide-beam antenna fabricated by etching the antenna element pattern in metal trace bonded to an insulating dielectric substrate, such as a printed circuit board, with a continuous metal layer bonded to the opposite side of the substrate which forms a ground plane. Common microstrip antenna shapes are square, rectangular, circular and elliptical, but any continuous shape is possible. Some patch antennas do not use a dielectric substrate and instead made of a metal patch mounted above a ground plane using dielectric spacers; the resulting structure is less rugged but has a wider bandwidth. Because such antennas have a very low profile, are mechanically rugged and can be shaped to conform to the curving skin of a vehicle, they are often mounted on the exterior of aircraft and spacecraft, or are incorporated into mobile radio communications devices. [2] Microstrip antennas are relatively inexpensive to manufacture and design because of the simple 2-dimensional physical geometry. They are usually employed at UHF and higher frequencies because the size of the antenna is directly tied to the wavelength at the resonant frequency. A single patch antenna provides a maximum directive gain of around 69 dBi. It is relatively easy to print an array of patches on a single (large) substrate using lithographic techniques. Misha Thakur,IJRIT
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Patch arrays can provide much higher gains than a single patch at little additional cost; matching and phase adjustment can be performed with printed microstrip feed structures, again in the same operations that form the radiating patches. The ability to create high gain arrays in a low-profile antenna is one reason that patch arrays are common on airplanes and in other military applications.[3] An advantage inherent to patch antennas is the ability to have polarization diversity. Patch antennas can easily be designed to have vertical, horizontal, right hand circular (RHCP) or left hand circular (LHCP) polarizations, using multiple feed points, or a single feed point with asymmetric patch structures.[4] This unique property allows patch antennas to be used in many types of communications links that may have varied requirements. The most commonly employed microstrip antenna is a rectangular patch. The rectangular patch antenna is approximately a one-half wavelength long section of rectangular microstrip transmission line. When air is the antenna substrate, the length of the rectangular microstrip antenna is approximately one-half of a free-space wavelength. As the antenna is loaded with a dielectric as its substrate, the length of the antenna decreases as the relative dielectric constant of the substrate increases. The resonant length of the antenna is slightly shorter because of the extended electric "fringing fields" which increase the electrical length of the antenna slightly. An early model of the microstrip antenna is a section of microstrip transmission line with equivalent loads on either end to represent the radiation loss. The dielectric loading of a microstrip antenna affects both its radiation pattern and impedance bandwidth. As the dielectric constant of the substrate increases, the antenna bandwidth decreases which increases the Q factor of the antenna and therefore decreases the impedance bandwidth. The radiation from a rectangular microstrip antenna may be understood as a pair of equivalent slots. These slots act as an array and have the highest directivity when the antenna has an air dielectric and decreases as the antenna is loaded by material with increasing relative dielectric constant. 2. Multi-band Microstrip Antenna
The antenna has been designed by combining two different geometrical shapes, that are a triangle and a rectangle (having same area), where one arm of the rectangle severs as the base to the triangular patch, as shown in figure 2.1,
Figure2.1: Top View of Multi-band Antenna and Measurement Specifications Primarily, the dimensions of the rectangular patch were calculated in accordance to dielectric used FR4 (Ɛr = 4.4), for a frequency of 2.4GHz. Figure 2.2 shows a side view and feeding positions of the antenna and also explains the type of materials used for different parts of the antenna.
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Figure 2.2: Side View Of Multi-band Antenna With Various Parameters
The table below explains the parameters considered for the designing of the antenna patch, Table 2.1 Design Parameters of The Antenna
Dielectric
Height of
Size of
Size of
substrate
rectangular
triangular
(mm)
Patch (cm2)
patch
1.575
2.93 x 3.8036
FR4 εr = 4.4
Size of slots(cm2 )
Frequency (GHz)
H= 5.86 1 x 0.5
2.4
B= 3.8036
2.1 Using HFSS 13 The software used for the designing and simulation of the microstrip patch is High Frequency Substrate Simulator (HFSS 13). The techniques of project variables have been employed, and the antenna is fed using a coaxial probe whose position is assigned using optimetric analysis. The figure below shows the top view of the antenna patch designed,
Figure2.3: Antenna As Designed In HFSS 13 Misha Thakur,IJRIT
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2.2 Results on Simulation of Microstrip Patch 2.2.1 Return Loss The antenna on simulation showed remarkable resonance on various different frequencies such as 1.69 GHz, 2.5 GHz, 3.4 GHz, 5.1 GHz and 8.1 GHz with a return loss of -19.958 dB, -20.967 dB, -14.1539 dB, -20.6167 dB, -12.238 dB and -14.0816 dB respectively (for an antenna to be properly resonant the return loss n a given frequency must be 9.5 ) The figure 2.4 is graph presenting the Return loss of the antenna designed and a table displaying all the marked values.
Figure: 2.4 Return loss of the antenna over various frequencies. 2.2.2 VSWR
The antenna is defined using another very important parameter i.e. Voltage Standing Wave Ratio (VSWR). For an antenna to be functional, the value of VSWR should be less than 2, for the given resonating frequencies. The graph here shows the value of VSWR over which the antenna was found to be resonating.
Figure 2.5: VSWR over Resonating Frequencies
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The table below, displays the values of the frequencies on which the antenna is resonating, return loss on that particular frequencies and there corresponding VSWRs.
Table 2.3: Values of Return Loss and VSWR over Resonant Frequencies Frequency(GHz)
Return Loss(dB)
VSWR( )
. 1.6992
-19.9583
1.5640
2.5789
-20.9673
1.6847
3.4586
-14.1539
2.1410
4.8797
-20.6167
1.4407
5.1729
-12.2381
1.7573
The table shows considerably good VSWR for almost all the frequencies and return losses but, the values of VSWR has increased the defined maximum value (2) on 3.4586 GHz frequency. 2.2.4 3D Polar Plot The 3 Dimensional radiation plot of the antenna designed can be seen in the figure below, The plot of radiation on the angle of azimuth and angle of elevation can be seen highlighted in red.
Figure 2.6: 3D polar plot
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2.2.5 Antenna Structure and Radiation over Various Optimetric Analysis
The Figure 2.7: Radiation Plot for Various Optimetric Analysis
The above radiation pattern for the antenna is shown in figure 2.7, this pattern is a graphical representation of optimized values of the coaxial feed pin, and on different values different pattern can be seen in different colour representations. 2.3 Antenna Applications The multi-band antenna thus designed can be utilised in various applications in wireless communication as it is a multi-resonant antenna and multi functional too. Each frequency here finds application in practical world ranging from Wi-Fi, spectrum profiles, outdoor Wi-Fi, Wi- Max, WLAN etc. 1.
1.6 GHz: GSM, ISM, WLAN, Navigational Signals, RFID applications.
2.
2.5 GHz: Wireless, CCTV, WLAN
3.
3.5 Ghz: Broad band in U.K., Telecom, Broadcast, WLAN, Wi-Max, Wi-Max 802.16a application.
4.
4.8 GHz: Annex 2, Tracking, Tracing, Data Acquisition, Downlink frequencies.
5.
5.1 GHz: High power Outdoor Wi-Fi Equipments.
2.4 Conclusion A multi-band antenna was designed by combining a slotted rectangular patch with a triangular patch having same areas. This multi-band antenna was designed and simulated and was found resonant on effective number of frequencies. All of the frequencies find application in practical world. Though, more improvements can be made in the result and gain in future. The antenna finds application in various fields such as GPS, Wi-Fi, Wi-Max, WLAN, telecom etc. 2.5 Future Scope This antenna can also be converted in to a wide-band antenna if engineered slots are cut into the triangular patch and also if the height of the substrate’s height is varied. Misha Thakur,IJRIT
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