[TowerTalk] Is it worth it to move 2El Quad from 50ft to 100ft?????

[jaw@lion.cc]

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 donīt 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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