3) You can change the size of the design by opting the rescale to new unit option to rescale the already used dimensions to the required new units. Unselect the rescale to new unit option to convert the dimensions to the required new units without making any changes in their scale.
4) Opt the Ok option to save the changes.
4.1.4 To Draw a model:
You can easily draw 3D objects by using the HFSS Draw commands. Objects are designed and shaped in the 3D modeler window.
To draw a waveguide rectangular in shape,
1) On the menu bar opt the HFSS option, opt the Draw. The Draw dialog box pops up. As we need to draw a cuboid opt the Box option.
2) Then draw the box and change the dimensions in the create box option. We can also change the co-ordinates of the box.
4.1.5 To Assign the Materials:
1) Firstly, Right click the mouse on the 3D modeler Window from the menu bar to get the 3D Modeller dropbox.
2) On the 3D Modeler drop box opt the assign material option.
3) The Select Definiton drop box pops up. Default in the system the entire list of materials in global library of materials available in Ansoft is displayed and we can assign material of our choice.
4) Select air or vaccum for the box.
5) Opt OK
6) The material of your choice is allocated to the object.
4.1.6 Assigning Boundaries:
1) Firstly Right click with the mouse on the 3D modeler window from menu bar to optfaces.
2) Opt on the faces option to assign which faces are to be allocated to be a perfect conductor.
Fig 22.214.171.124 Assigning boundaries
Fig 126.96.36.199 Assigning finite conductivity to box
3) On the menu bar select HFSS menu, opt the Boundaries, choose assign Boundary and opt finite Conductivity.
4.1.7 Assigning excitations:
The Excitations in HFSS design is utilized to specify the sources of electromagnetic fields and surges, currents, voltages in surfaces or objects in the design.
i) we have to assign port
ii) we have to Assign the Integration Lines or the Terminal lines discretely for every mode.
i)For Assigning ports:
1) select the object face to that which you want to assign the port.
2) Choose HFSS->Assign->lumped port
Fig 188.8.131.52 Assigning ports
3) The option named wave-port pops up when we select assign excitation option.
4) Give the port a name of your own choice in the Name text box or simply give the default name and then opt next.
5) To specify more number of modes, type a required value in the New number of modes dropbox and choose the update option. The new modes spreadsheet is now changed with the new values.
Fig 184.108.40.206 Assigning multi modes
Go to the solution set up and add set up
Fig 4.1.8 Adding set up to the solution
4.1.9To validate HFSS design
Fig 4.1.9 Validating the design
4.1.10To analyze the design
1) On the HFSS menu, click Analyze
Whenever a simulation is running, you can keep a check on the solution’ in the Progress window
Fig 4.1.10 Simulation running on local machine
Antenna is designed in two iteration stages which we got the desired results in second iteration stage compared to first iteration stage.
1ST iteration stage 2nd Iteration stage
Fig 4.2 Fractal monopole antenna
Parameters Dimensions(mm) Parameters Dimensions(mm)
W’ 26.50 Fw 01.50
L’ 47 Fl 16.50
S1 20.50 Gw 25.50
S2 06.00 Gl 16.00
S3 06.25 Sw 02.50
S4 02.50 Sl 12.00
S5 02.00 w’ 02.50
TABLE 4.2. DIMENSION OF AN ANTENNA
Fig 5.1 S11 parameter of 1st iteration stage
Fig 5.2 S11 parameter of 2nd iteration stage
Fig 5.3 at 5.4 GHz of 1st iteration Fig 5.4 at 5.4 GHz 2nd iteration
Fig 5.5 3D polar plot at 5.4 GHz 2nd iteration
Fig 5.6 VSWR
6.1 Results and Discussion:
This fractal structure (fractal monopole antenna ) shows a good results in second Iteration than first iteration . we obtained good wide band width from 3 to 6.3 GHz which covers IEEE 802.11 WIMAX (3.5 -5.5 GHz) and WLAN(5.2 -5.8 GHz) applications. We obtained the constant gain and got the best voltage standing wave ratio (VSWR) which is less than 2 in the range from 3 to 6.3 GHz. The peak gain obtained is 5.1dbi at 5.8 GHz in the second iteration stage and 5.01 at 5.4 GHz but in the first iteration stage We got less than second iteration which is 3.9 dbi at 5.4 GHz. parametric analysis is done and observed the results. Effect of ground plane and When the ground length increases the impedance bandwidth but there is decrement in |S11| and also slot width has direct effect on |S11| and slot length is directly proportional to change in S|11| .Simulated results are observed especially it useful for WIMAX and WLAN applications. The constant gain is obtained at all the frequencies.
• Some of the applications of UWB are there are used in wireless networks and wireless home systems such as computer etc.
• Mainly it is used in Radar applications.
• Wireless networks such as WPANS and Wi-max are some of the applications of the UWB.
• UWB band requires antennas which are having high gain.
• This antenna can be used in high gain applications.
• They can also serve best in military and civil applications.
A fractal monopole antenna is designed in this paper and obtained good results. Wide band width has been obtained which is from 3 -6.3 GHz useful for wide band applications . The proposed antenna has been illustrated iteration wise. The proposed antenna is useful especially for WIMAX (3.5 -5.5 GHz) and WLAN(5.2 -5.8 GHz) applications. The maximum gain and constant gain is obtained at all the frequencies the maximum gain is around 5.1 dbi . The proposed antenna had its applications at high gain devices which are present in the ultra-wide region. The compared results show that the designed antenna can improve obviously the radiation performance especially near the resonance frequency band.
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