Topband: Spitfire.......one more question

[Eduardo Araujo]

Hi Topbanders, I am preparing my next move with the spitfire. 

I have one more question (for those with modeling tools?).

In order to detune the elements to allow omnidirectional radiation from the vertical, authors suggested to ground the elements where they are switched from director to reflector which will give you aprox 74.5 mts long element grounded at the base.


In my case I have a relay installed at the corner of the elements which when opened leave only 53.6 mts sloping in the space from the top of the 1/4 wave tower to 40 mts from the base and 3 mts from ground.


My question is, could it be possible instead of grounding it or leaving it opened, to add an inductor or a capacitor at that 53.6 mts point in series with the remaining element (24.0 mts for the reflector and 17.6 mts for the director) in order to make them invisible to the tower?


So in case of the reflector I should have 53.60 mts, an inductor and then 24.0 mts. For the director 53,60, inductor and 17.6 mts.


Could it be possible to estimate its value with a modeling tool?


I think to remember that during the Project development and QA, someone modeling the antenna said that 53.6 mts hunging on the space will have little current on it so he felt it would not be necessary to ground it but I can not remember who said that to ask him and be sure I am not influencing its omnidirectional property leaving the elements floating.

During my next move, I will use AIM4170 before to install the elements in order to see if I am able to notice a change in the antenna base parameters indicating interaction with the floating configuration.... Am I correct with this thinking? 

Many thanks in advance if someone wish to model it for me or sharing your thinking..... Eddie, LU2DKT