Topband: conclusion : Sunset / Sunrise and low dipole question

Gilles RENUCCI ve2tzt at arrl.net
Wed Nov 28 23:33:47 EST 2007


Thank you to every contributors, you have helped me to take the decision : I will install soon a low dipole.

Every contributor have ever verified that there are circumstances (rarely for some and frequently for others, perhaps the geographic position) when the low dipole is better than a vertical. Furthermore, some have even experimented dx contacts impossible otherwise.

It seems that it can happen not only during sunset / sunrise but also during geomagnetic storms (high K index).

Majority is confirming that what is involved in the low dipole is its high angle lobe which permits to transmit/receive signals that the vertical/beverage cannot. One contributor seems to think that polarization could have a role.

Heigh of the dipole does not seem critical and is usually between 30 and 120 feet (even if 120 feet is pretty high for most of us, it is low for the 160m). 

If I suppose that high angle is the main reason, I can use any orientation for the dipole (because it has no directivity at high angles) and choose the one which minimize the local ground wave qrm (keeping in mind that the groundwave directivity of a dipole is 90 degrees of its skywave directivity : the maximum groundwave reception is to the antenna ends and minimum is broadside) 

73, Gilles / VE2TZT



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