[TowerTalk] Vertical question

[Mike Smith VE9AA]

de VE9AA

 

Because I am a doubting Thomas type of guy when it comes to trusting
folklore about antennas, I actually tried this as a real world test a few
years ago.

 

I have 2 x 160m inverted L's here 120' apart.  Both go up (sloped) around
50-60', then over 50-60', then down 20 feet or so. (like an inverted J)

They're not perfectly symmetrical, but were close enough to satisfy my
curiosity.

 

One has 2 raised radials aprox 10' high and 127' long @ 90* to one another.
(180* would be better, but I don't have the room)

This one overall is a little lower and lazier than the other one and one
radial zig-zags a little up/dn and around  the corner of the property. (just
the way the trees are here).nothing is perfect here.

 

The other inverted J, has many thousands of feet of copper in and on the
surface of the ground. I started with about 60+ 127' radials, so that
equates to about 7620' of radials, but I've lost a few over the years due to
the mower, a gopher, me tripping,  etc.  Let's say I have even only 6620' of
radials on the ground. They're not perfectly symmetrical around the vertical
either though due to constraints in the yard, having most of the radials in
the southern hemisphere of the antenna and only a few bent ones north ,
northwest or northeast of the antenna.

 

What I found was that:

Most of the time through an A/B switch the verticals were close enough that
I would really be guessing which one was loudest/best and other times the
one with all the 60 on-ground radials was definitely best by a small margin.
I can't ever say with confidence the one with 2 raised radials was best.

 

My test is slightly flawed not only because both antennas are not perfect
copies of one another, but I didn't short or open either one when doing my
tests and there are lots of antennas in the near field to both, but
especially closer to one of them.  This testing was before I was used to
using the RBN and what it could do for me.  Today I would definitely do
proper RBN comparisons for sure. Maybe that would open my eyes to a larger
difference or maybe it would show nothing. One is left guessing.

 

As it was, I just listened to DX stations. QSB and whatnot makes this tough
to call.

 

It was enough though to tell me that 2 raised radials was "good enough" for
the type of radio work I do. Is it down a dB or two? (probably)

 

If I owned a copper mine or was wealthy then I would definitely do 120 on
ground radials for each of them.(or maybe 8 raised radials if I had the
land, but I don't)

 

I would also do the same for all my 4-squares, however all my 4 squares
(20-40-80 and soon 10 & 15) will just have 2 raised radials each.

 

Scientific? Not exactly, no.

 

Better than anecdotal (imo) - yes !

 

FWIW to y'all

 

Mike VE9AA

 

=================

How do you know that there is a huge difference?

 

John KK9A

 

Jim N9WW wrote:

 

I'll take my elevated 40/30M vertical at 30' with 8 radials over any ground
mounted vertical with 60+ radials. Been there done that. Huge difference.

 

73,

Jim N9WW

 

Mike, Coreen & Corey

Keswick Ridge, NB