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Computer Modeling

I've used some computer modeling to help prove out these designs before building them for testing. I've found the computer modeling to be fairly accurate and a great way to get me in the ball park. This computer modeling uses the NEC2 calculation engine which simulates the currents and voltages flowing through the wires. I use both EZNEC and 4NEC2 for modeling, 4NEC2 is a program that is very powerful and can be downloaded and used for free. The plots on this page are the result of computer modeling and the predicted gain curves and reception patterns.

These plots are a good representation of how different whisker and reflector configurations will change the reception patterns. The 10" x 9 1/2" and 9" x 8 1/2" patterns are similar just the curves are shifted higher or lower.

M8 Computer Models can be seen here.

Click on the plots for a larger View

9 1/2x9 no reflector 470mhz 9 1/2x9 no reflector 602mhz
9 1/2x9 no reflector 686mhz 9 1/2x9 no reflector VHF-hi reception pattern

Above are the predicted reception patterns of a M4 4bay 9 1/2" x 9" without a reflector for UHF and VHF-HI

Below are the predicted Raw Gain and SWR plots for the same antenna.

no reflector raw gain

no reflector UHF SWR

9 1/2x9 no reflector VHF-HI raw gain

9 1/2x9 no reflector VHF-HI raw gain

9 1/2x9 flat reflector and whiskers 9 1/2x9 flat reflector and whiskers
9 1/2x9 flat reflector and whiskers 9 1/2x9 flat reflector and whiskers

Above are the predicted reception patterns of a M4 4bay 9 1/2" x 9" with flat whiskers and a 40" x 40" reflector for UHF and VHF-HI

Below are the predicted Raw Gain and SWR plots for the same antenna.

9 1/2x9 flat reflector and whisker UHF raw gain

9 1/2x9 flat reflector and whiskers UHF SWR

9 1/2x9 flat reflector and whiskers VHF-HI raw gain

9 1/2x9 flat reflector and whisker VHF-hi SWR

9 1/2x9 rear swept 9 1/2x9 rear swept
9 1/2x9 rear swept 9 1/2x9 rear swept VHF-hi

Above are the predicted reception patterns of a M4 4bay 9 1/2" x 9" with rear swept whiskers and a 40" x 40" reflector with 5 1/2" spacing for UHF and VHF-HI

Below are the predicted Raw Gain and SWR plots for the same antenna.

9 1/2x9 rear swept UHF Raw gain

9 1/2x9 rear swept UHF SWR

9 1/2x9 rear swept VHF-hi raw gain

9 1/2x9 rear swept vhf-hi SWR

9 1/2x9 forward swept 9 1/2x9 forward swept
9 1/2x9 forward  swept 9 1/2x9 forward swept

Above are the predicted reception patterns of a M4 4bay 9 1/2" x 9" with 2" forward swept whiskers and a curved 40" x 40" reflector for UHF and VHF-HI

Below are the predicted Raw Gain and SWR plots for the same antenna.

 

9 1/2 x 9 raw gain UHF
9 1/2 x 9 SWR curve UHF
9 1/2 x 9 raw gain VHF-hi
9 1/2 x 9 SWR curve VHF-hi

M8 Computer model Data