At 09:40 PM 2002-07-06 -0400, Tom Rauch wrote:
>While it makes good marketing hype, the number of countries worked
>has little to do with transmitting antenna performance, unless
>something is seriously wrong.
>One reason so many people have dismal results with base-loaded
>antennas is they swallow the "BS" about only needing a few radials.
>Factually, there is almost no difference between base and top loading
>if the ground system is good. Top loading does provide about four
>times the radiation resistance of base loading, but top loading
>generally has (for a given radiator size) less bandwidth.
I always thought that the radiation comes from the place where the current
is the highest, ie at thepoint of feed for a dipole and a 1/4 wl. Hence
the further away from the feed point (to limits of course) the inductive
load is the better, then the next is to change the inductor to linear
load. That being all other variables constant.
>If the ground system is poor, top loading can reduce loss by up to a
>factor of three or four. If the ground system is good, efficiency
>changes are often not measurable.
Now what is a good ground system? I have read 4 radials is good but some
say anything less than 16 is poor. The idea that I like is 4 elevated
radials. (If about 5ft will stop the kids running through the yard and
hitting the guys.)
>Most of the DXCC totals do with hours operated, location, and
>operating skill. I'd say transmitting antenna performance is way down
>the ladder, unless someone really has a poor antenna installation.
From what I have seen, I concur with hours, location and skill, with
location probably being the most important. (I have no good north to north
east exposure, hence Europe is out.)
Chris opr VE7HCB
>73, Tom W8JI