If you have flat terrain you would sure see an big improvement. Compare the
vertical radiation diagramm for both heights (see the chapter "The effects of
Ground" in the ARRL Antenna Handbook) and you will see the difference.
For 20 Meters this means:
50 ft high (0,75 lambda): a main lobe just right up at 90 degrees - this is
only usefull for short distances and a waste of power for DX. The second lobe
is at about 20 degrees, still rather high for DX.
100 ft.high (1,5 lambda): The highest lobe is at 57 degrees, much less power at
90 degrees. Your lower lobe is at 10 degrees. That sure makes a difference on
DX !
If you don´t have flat terrain there, the situation may be completely
different. You should use the programm "YAGI-TERRAIN" to analyze your situation
and find out the best height for your antenna. This software comes with the
ARRL-Antenna book (see last page). The programm does not include quad-antennas.
Use a 2 or 3 el yagi for modeling! There is almost no difference in the
vertical radiation between quad and yagi!
You will also find valuable information in this programm for the flat terrain
situation. There are some files which give you the probability for a specific
radiation angle. Then you can find out what are the most probable radiation (or
arrival) angels for a specific path (USA to Germany for example). Out from this
probability you will be able to make a decision.
With irregular (sloping) terrain you may find out that 100 feet could even be
to high! So better model your situation before buying another tower.
73s
Juergen - OE5CWL
>
> Von: Jack <poster@gate.net>
> Datum: 2001/10/16 Tue AM 05:19:59 CEST
> An: "towertalk@contesting.com" Is it worth it to move 2El Quad from 50ft to
> 100ft?????
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