Microwave Project

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Dipole Array Antennas Software simulation

Microwave Engineering Project

Submitted to:- Submitted by:-Prof. Vijay Kumar Shoury Priyanshu

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AbstractThis project deals with the simulation of 2x2 dipole array antenna using AWR

microwave office software.

Arrays of antennas are used to direct radiated power towards a desiredangular sector.

The number, geometrical arrangement, and relative amplitudes and phases ofthe array elements depend on the angular pattern that must be achieved.

By using AWR microwave office the s11 parameter will be calculated.

Introduction



Dipole antenna consists of two equal length poles, and the power is applied tothe center feeder. It is a very basic construction of a single dipole antenna, andthe power transfers to or receives from the antenna through the feeder. In thisreport, I would build an ideal dipole antenna, which is same to the half wavedipole antenna.



Antenna Design

The 2 by 2 Dipole Antenna array was designed for 2.4GHz. Half-wave DipoleAntennas were designed, and consisted of two quarter-wave wires. Thelengths of the copper wires were calculated using the desired frequency,2.4GHz, and factor A, which relate the diameter of the copper wire to the

wavelength the ratio of was used to find the appropriate Factor A

from the chart provided on Electronics Radio Today (2012). The calculations

are provided below. The length of each segment was 3cm.

Wavelength = = = 0.125m = 12.5cm

Half wave length = = x 0.5 = x0.5 =0.0625 =6.25cm

Length of the total wire = x factor A

= x 0.5 x factor A

= x 0.5 x 0.96

Length of the total wire = 0.06m = 6cm

Each wire segment =0.5 x length of total wire =0.06/2= 3cm.

Factor A = = = 153.94



Estmation of radiation pattern

After the lengths of the Dipole antennas were calculated, the estimation of theRadiation pattern of the 2 by 2 array was determined using the elementpattern and array pattern factor.

The initial design was for separation between the Dipoles on the samelevel and separation between the two-sets of Dipoles.

The radiation pattern was estimated with the 2 by 1 Dipole with d= /2separation using the Dipole element pattern, shown in the figures below.

We can see clearly the 3D radiation pattern and its horizontal andvertical pattern in the Figure 3. When we look at the vertical pattern,we can see that direction of maximum radiation is at right angles tothe axis of the antenna, which are 90 and 270 degrees in this case.



Design

The Wilkinson Power divider 2 by 2 MonopoleAntenna Array

The 2 by 2 Monopole array has similar properties to that of theDipole array. The radiation pattern of the Monopole is similar to thatof a Dipole, but the Monopole needs a large conductive plate to

replace the other wire half. To determine the dimensions of a 70.7Ωpiece of quarter- wave aluminum foil, Microwave Office’s TXlineeditor was used. The design constraints were the insulator thicknessof 0.23 inches, the thickness of the aluminum foil was 0.016mm, andthe 2.4GHz frequency, as shown in the figure below. The dielectricconstant of the wood insulator was assumed to be but thedielectric constant of wood varies with the type of wood. Thedimensions of the aluminum foil were estimated to be 1.04 inches by.55 inches, with a thickness of 0.016mm. The design required threestages of the Wilkinson power divider to accommodate the fiveconnections required, four for the antennas, and one for theconnection to the spectrum analyzer.

The very left port works as the port to the four ways power dividerwhich is the two way power divider; and it separate into another twopath connect to the other two way power divider. Finally, the foursingle half-wave dipole antennas connect at the end of the fourconnections of these power dividers.



Figure: Power division using Wilkinson Power divider

Figure: Block diagram representation.

Four way power divider



= = = = = 100Ω

= = = = = 100Ω

Where =50 Ω, = 70.7 Ω

= 100Ω || 100Ω =50 Ω

The Wilkinson Power divider matches the input port to 50Ω, withfour output ports. The microstrip transmission lines have quarter-wave properties and since the four loads connected should be thesame ideally, 50Ω, after the quarter -wave microstrip increases theviewed impedance to 100Ω.

The 100Ω impedance in parallel results in 50Ω at the end of eachWilkinson power divider stage. the100 Ω resistors are assumed to

not be dissipating power The Wilkinson power divider is assumed



have equal loads so that the 100 Ω resistors can be ignored, sincepotential is the same at both sides of the resistor. The plot fromMicrowave Office of the schematic and the simulation of the 2 by 2

array’s r adiation pattern are shown above .

Conclusion

The radiation patterns for the 2 by 2 Dipole antenna showed somesimilarities in the XZ-plane and YZ-plane. After building the 2 by 2Dipole and Monopole arrays, the exposure to new concepts such asmicrostrips and striplines were made easier to implement with theaid of software, such as Microwave Office and 4nec2.

Reference:

1) A basic report on dipole array antenna by Hanbo tao from san josh state university.

2) Electronics+Radio Today. (2012, November 18). Retrieved November 18, 2012, from Electronics+Radio Today:http://www.electronics-radio.com/articles/radio/antennas/Dipole/Dipole-antenna.php

3) Balanis, C. (2005). Antenna Theory 3rd Edition. Hoboken, NewJersey: John Wiley and Sons.

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