Design And Implementation Of Wire Antenna Of 2.45GHz For Various Application

Design And Implementation Of Wire Antenna Of 2.45GHz For Various Application

Abstract:

This report presents wire antenna for Bluetooth, wireless local-area network (WLAN), world interoperability for microwave access (WiMax), S-DMB and Wi-Fi applications. The proposed antenna fed by a 50Ω coaxial line occupies bandwidth is 170MHz (2.37–2.54 GHz) and S11 is less than -10dB, and the measured gain is 2.33 dB at 2.45 GHz. The simulation is employed for optimizing the design parameters, and the simulated results well agree with those of the measured one.

 Introduction:

Recently there is tremendous demand for the development of wireless communication systems for local access networks (WLAN) including Bluetooth, IEEE 802.11a, and 802.11b. This demand has stirred significant renewed interest in antenna design particularly at the ISM bands. Many novel antenna structures for single, dual, or multiple bands have been proposed.

Wi-Fi allows the deployment of local area networks (LANs) without wires for client devices, typically reducing the costs of network deployment and expansion. Spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.As of 2010^[update] manufacturers are building wireless network adapters into most laptops. The price of chipsets for Wi-Fi continues to drop, making it an economical networking option included in even more devices. Wi-Fi has become widespread in corporate infrastructures. Different competitive brands of access points and client network-interfaces can inter-operate at a basic level of service. Products designated as “Wi-Fi Certified” by the Wi-Fi Alliance are backwards compatible. “Wi-Fi” designates a globally operative set of standards: unlike mobile phones, any standard Wi-Fi device will work anywhere in the world.

Figure 1 shows the proposed antenna configuration at X-Y plane. Here numeric digit represents the wire number. The length of wire no. 32 is 5mm and rest wires are 12mm long each. The radius of each wire is 1.02626mm.The coaxial feeding is connected at wire no. 19.

antenna structure

Simulation and measured result:

In all figure frequency are calibrated in MHz and plotted in X axis and another parameters are in terms of db.Here Figure 2 and figure 4 represent the simulated radiation pattern at horizontal plane and vertical plane respectively. Figure 3 and figure 5 represent the measured radiation pattern at horizontal plane and vertical plane respectively. In both case we get better output at vertical plane than horizontal plane. S11 parameters are represented by figure 6, 7, 8 and S21 parameter is represented by figure 9.From figure 6 we see that VSWR at center frequency of this antenna (2.45GHz) is 1.00161 and from 2370MHz to 2546MHz VSWR is less than 2.Figure 7 shows that reflection coefficient at 2.45GHz is -61.871 and from 2374MHz to 2540MHz reflection coefficient is less than -10. We can make decision from figure 7 that the bandwidth of this antenna is 170MHz (2370-2540MHz).It is clear to us from figure 8 that the impedance and the radiation resistance or the real part of impedance is almost same around 2.45GHZ which is equal to 50Ω approximately. The impedance is 50.097Ω at 2.45GHz. The gain is fluctuating within a short range (2.3db-2.35db) from 2450MHz to 2550MHz indicated by figure 8.At 2.45GHz the gain is 2.33db.

 

experimental result

Simulation result:

Simulation result

The measured values of VSWR and return loss are given bellow:

Position	Attenuation	VSWR	Return loss(dB)
vertical	0dB	1.0038	-54.41
vertical	-4dB	1.0196	-40.24
vertical	-8dB	1.0856	-27.73
horizontal	0dB	1.0095	-46.51
horizontal	-4dB	1.0490	-32.42
horizontal	-8dB	1.1590	-22.67

Table1: Measured VSWR and return loss for various attenuation

The results are relatively close to those predicted by the simulation, but the radiation pattern is distorted, this could be because of the following reasons:

· Reflections – reflections from objects in the room, the walls, floor and ceiling caused significant distortions in the radiation patterns. The plots that were reasonable and which were used for this analysis must still have been degraded by these reflections and since they were not taken into account in the simulation they could account for the discrepancy.

· Construction – During the design process it was found that small changes in the element length or separation can cause large changes in the characteristics of the antenna, therefore any measurement errors introduced during the construction of the antenna could cause the real antenna to perform quite differently to the predicted.

Conclusion: Found that the design process is extremely complicated; with many interacting parameters it is hard to optimize the many characteristics of the antenna simultaneously. The experimental antenna performs relatively similar to the simulated one, the shape of the simulated radiation patterns are of the same form as the experimental, but there are a number of distortions and the frequency shift give the simulation limited real world value. It is clear that the approximations made in the computer model do not allow accurate modeling a real antenna .On the other hand it would also be extremely difficult to design a antenna without simulation software.

Reference:

1. PRINTED STRAIGHT F ANTENNAS FOR  WLAN  AND   BLUETOOTH,   H.Y.   David Yang

Dept. of Electrical and Computer Engineering, Univ. of   Illinois  at  Chicago,Chicago,  IL 60607.

2. A Compact Loop Type Antenna for Bluetooth, S-DMB, Wibro, WiMax, and WLAN Applications

Yong-sun Shin and Seong-Ook Park, Member, IEEE

3.A COMPACT PRINTED HOOK-SHAPED MONOPOLEANTENNAFOR2.4/5-GHz WLAN   APPLICATIONS,  Chi-Hun Lee and  Seong-Ook Park .