The Imax 2000 is 24ft long and is actually a 0.64 wave antenna. Its smaller sibling the A99 is a halfwave.
Hey MOGVZ.
I agree that making an Imax 0.024% longer to get to 0.64 wave length will likely result in a small increase in the gain. My Imax models shown below are all set at 268.5" x 0.125" inches for the wire radiator, It is fair that folks might disagree, but we are not talking about much difference here, and I don't believe this 0.64 issue is the big mystery we hear talked about.
At 268.5" inches the radiator wire on my model below shows 3.97 dbi @ 9* degrees. When I add 6.5" inches to the 268.5" the radiator = 275" inches. The model shows increased gain to 4.06 dbi at 9* degrees. So, there is improvement to be noted.
A while back some of the members had a discussion about the Imax having a capacitor in the center of the middle element. Click the link below. I think this is where the ideas form a Ham operator named Dave with a handle "Radio Daze" got us talking about this possible issue with the Imax.
http://radioaficion.com/cms/solarcon-i-max-2000/
IMO, this is probably the mystery we should be considering as to why the Imax performs as well as it does in the models I posted below. If my models are close to accurate...then here is a difference that matters...and IMO this is likely the real mystery.
Models
1. Control Center of Eznec showing the Average Gain results for the model below.
2. this model is a
Free Space model with a 40pF capacitor in the middle section of an Imax with slanted down radials. Also included is a radiation pattern indicating the maximum gain and angle.
3. this is the same model as #2 and is over
Real Earth. It also includes a feed line choke at a point level with the bottom of the ground plane radials. Also included is a radiation pattern indicating the maximum gain and angle.
4. this is the same model as #3 without the choke, primarily to show how the common mode currents ill-effect the pattern, and maximum gain and angle.
5. Control Center of Eznec showing Average Gain results of the model below.
6. this model is in Free Space without a 40pF capacitor in the middle of an Imax with slanted down radials.
7. this model is the same as #6. Also included is a radiation pattern indicating the maximum gain and angle which looks
bad without the Imax capacitor in the middle sexton.
8. this model over Real Earth with no capacitor in the middle section. Included is a pattern showing the ill effects on maximum gain and angle.
At the end I included comparison overlays for the models over real Earth. Note: "wC40pF" vs. "nC40pF" in the titles for the models,
meaning with a 40pF capacitor and without.
The (*) in front of the model listed indicates the active model results for maximum gain and angle on these overlays.
... !
