I have downloaded an antenna modelling and optimization software "4NEC2" from:
http://www.qsl.net/4nec2/ .
It is not as sophisticated as the commercial software EZNEC, but it is very good considering that it is free of cost.
I then simulated Franklin I have built, and following 3 screenshots show the results:
(see screenshot 3 - maximum gain =6.95 dBi, SWR =2.49 when connected to 75 ohms cable/receiver)
1 - INPUT - WIRE GEOMETRY DATA
4nec2-franklin-input-geometry data.png
2 - INPUT - LOAD/SOURCE DATA
4nec2-franklin-input-source-load-data.png
3 - OUTPUT - SWR, GAIN, IMPEDANCE, RADIATION PATTERN
4nec2-franklin-output-gain-swr-pattern.jpg
4 - OUTPUT - SWR vs FREQUENCY SWEEP
4nec2-franklin-output-sweep.png
Edited: Originally posted screenshots have been replaced on 28 January 2014, after correction of error in source/load configuration, and re-runnig the modeller's calculator.
.
http://www.qsl.net/4nec2/ .
It is not as sophisticated as the commercial software EZNEC, but it is very good considering that it is free of cost.
I then simulated Franklin I have built, and following 3 screenshots show the results:
(see screenshot 3 - maximum gain =6.95 dBi, SWR =2.49 when connected to 75 ohms cable/receiver)
1 - INPUT - WIRE GEOMETRY DATA
4nec2-franklin-input-geometry data.png
2 - INPUT - LOAD/SOURCE DATA
4nec2-franklin-input-source-load-data.png
3 - OUTPUT - SWR, GAIN, IMPEDANCE, RADIATION PATTERN
4nec2-franklin-output-gain-swr-pattern.jpg
4 - OUTPUT - SWR vs FREQUENCY SWEEP
4nec2-franklin-output-sweep.png
Edited: Originally posted screenshots have been replaced on 28 January 2014, after correction of error in source/load configuration, and re-runnig the modeller's calculator.
.
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