[TowerTalk] Can take-off angle be too low?

[Ken Hirschberg]

In a message dated 6/29/00 6:16:46 AM Pacific Daylight Time, 
tonno.vahk@hansa.ee writes:

<< Subj:     [TowerTalk] Can take-off angle be too low?
 Date:  6/29/00 6:16:46 AM Pacific Daylight Time
 From:  tonno.vahk@hansa.ee (Tonno Vahk)
 Sender:    owner-towertalk@contesting.com
 To:    towertalk@contesting.com
 
 
 Hi, I would like to hear your opinions about that topic. I have found
many
 contradictory thoughts on it and very few clear and reasoned statements
 really.
 
 How important is it to have the ability of running very low elevation
angles
 in upper HF contesting? How much does it add to the score if one can
run 10
 meters with beams higher than 200 feet and get the take-off angle down
to
 2-3 degrees? Here assuming one has also lower beams available. N6BV
 statistics actually indicate the high theoretical QSO percentage at 1-3
 degrees. To my mind it contradicts the somewhat common opinion that low
 angles get very little use. Would an efficient solution be to have one
stack
 at 230 feet (e.g. 5/5) and one at low height if there was so high tower
 available to be able to open the band early, be strong meanwhile and
close
 it late? All this having flat ground in mind for simplicity.
  
 73s Tonno ES5TV   t.vahk@hansa.ee
  >>
 
Looks like N6BV's theory was given some pretty good vindication during
the contest last year where the high scoring station was using all, or
almost all, F-12 verticals next to the beach.

If you would like to emulate beach front property on all that flat land,
especially on the lower bands, a near-maximum-size compact transmitting
loop over a good ground screen will get _all_ the angles, from amazingly
low to well above 50 degrees without notches in its bi-directional
lobes.  Because of the low phase center of these antennas, a  much
smaller ground screen, say one with half the area of an "FCC" vertical,
(e.g. 120 radials of 0.4 lambda etc.) will produce takeoff angles with
-3 dB points around 5 degrees.

73, Ken

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