Topband: vertical 160/80m

[Ryszard Tymkiewicz]

Hello All,
I asked already about this subject but still I'm not sure what to do
specially after last e-mails regarding DL0AO verical.
I'm going to build a vertical for both 80/160m but I'd like to have 
equally good performance /maybe its not possible/ on both bands.
I'm going to have burried radials and I'm going to make 30m  high 
mechanical part and add 4 wires as a hat for 160m.
W8JI wrote "If it was a 100 ft vertical with all hat it would indeed behave like a
near-1/2 wl on 80" ,so I'm afraid it will be too long for 80m.
I know Bob W7LR is using 90 ft verical for both bands but maybe its
better /for 80m/  to use "isolating trap" between the hat and the top of the mast?
I will build in a Summer so I still have a time but its important for me to know
what the height will be the best so which construction to choose.

                    I hope you are able to solve my doubts

                                73 Rys SP5EWY