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23.10.17

TONNA 20438 antenna UHF F9FT cross 2X19 ele. antenna discussion



TONNA PART No 20438
UHF 2X19 ele. antenna

Now i have some problems to solve that is dedicated especially to this TONNA 20438 antenna  UHF F9FT  cross 2X 19 ele antenna.
1. This antenna, is not like the VHF cross TONNA's antenna part No 29818 (remind that at new TONNAs added number TWO (2) in front of the old part Nrs)
they DO NOT NEED matcing-stub 50 ohms coax
 Phisically constracted the delay by distance 1/4 λ the other polarization antenna aray on the same boom laying.
to make RHCP & LHCP  at the UHF you do not need to add matcing stub 50Ω .
Only T mach with two equal coax feeding lines 75 ohm λ/4 - VF  (fig 1)

2 . Always the RHCP (or LHCP) polarization is recognisable by looking the "antenna" from the front side. Usually instruction are given looking antenna from the back but don't mess it. 

3 Now the problem is to change from RHCP to LHCP. This can be done changing the feeding on the second aray from left to the right  when you are looking antenna from the back . Thus just changing  shield with inner conductor in the same length coax.  the problem is to not prolong the one from other feeding coaxial 75 ohms

4. When you have the power divider must find a way to make this polarization change? resolving
at the same time and the problem Νο 3 . fig 2


5. Why the antenna bracket is not constructed for X setting ???

More fudtamental information on sat. antennas can be found on the website from SV1BSX, the article he wrote is a great source of information if you want to learn more about polarization. Unfortunately he is SK but we keep his site alive.





fig 1




fig2

fig3

Setting up new Satellite Set

this is the solution for the No 4 question

fig 2




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Long wire muching


Portable Satellite Antenna Base

 an old setting



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