[Antennas] elevated radial opinions requested

Fri Jun 18 11:31:17 EDT 2010

Hello Brian,

	Well, the 4 radials X 33' will give you suitable radials for 40M,
but if you want more bands than that you need 4 Radials PER BAND. Having
done this in the past I can tell you it works just fine. Higher would be
better because you would reduce the ground coupling effects (and losses) but
put it up as high as you can manage. I had mine on the roof clamped to a
short mast clamped to the bracket for my Air Conditioning Unit! I never
worked better since then.
	There are several schools of thought at work here as well RE: Radial
Tuning.
	Tuning the radials to some magical exact frequency is also NOT
necessary. Get them in the ball park. Use the "Factory Recommended Default
Lengths" from the instructions and be done with it.  WHY? Because tuning
them in the air is a job for those you wish to inflict horrible mental
anguish upon due to the frustration of getting one set resonant and then
having it de-tuned by the next set. You will need a long sleeve sweater that
ties in the back after attempting that!
My medication works well but that could push anyone over the edge!  ;>)
	The reality of it is that if you think of a bent half vertical
dipole (model it in EZNEC if you have it) then you can see that if the
horizontal leg (think One Radial) is long or short makes no difference
because you can adjust the vertical part to resonance anyway. Add more
radials, it becomes even better IF the horizontal half is NOT the exact
center because it allows the vertical part to be adjusted to match a 50 Ohm
coax (think off center fed antenna) because the REAL impedance of a vertical
is about 36 Ohms when the radials are horizontal. If you slope them down a
bit (about 120 Degrees) then the antenna is almost exactly 50 ohms when
exactly center fed. IE: all elements are the same length.
	DON"T forget to either use a balun at the feed point and IF the feed
line is also elevated then use another common mode current choke at the
point where it equals the length of the longest radial or attaches to the
house, just before it enters the house so it becomes properly decoupled from
the current flowing in the radials. If the feeling just runs down and then
lays on the ground or just under the ground, then a current choke (beads or
linear coil of coax) at the feed point is usually enough.
	Want to save $$$ on the choke balun, make one or two a single layer
coils of coax around a 2 liter Soda Bottle and wrap with Duct Tape. It work
fine especially if you are only going to need it for a year or two. Mine
lasted 5 years in the Arizona Sun but the bottle was completely wrapped in
Duct Tape to keep the exposure to the sun to a minimum and not have the
bottle disintegrate.   
	Back to part of your original question: " what would I gain or lose
from doing so?" You will have a system that has a fairly resonant radial
system for each band and won't drive you nuts trying to get the balance of
the antenna tuned. With a bit of patience and keeping the order of
adjustment correct, you should be able to get the SWR down under 2:1 across
all of the bands EXCEPT 75/80 Meters. There you take what you get due to the
effects of the coil, the shortened length of the vertical element, smaller
diameter to Frequency ratio of conductors, etc.

	Good luck and drop me a note if you have any questions.

	BTW, no shameless plug for DX Engineering intended but their 17M add
on kit and stainless fold over base plate make that a very nice antenna to
use and work on. I must have spent 40 trips up and down the ladder to my
roof trying to get things tuned correctly (due to the previous owners ugly
settings) and tipping it over without the tilt plate nearly did me in. NEVER
again without the tilt plate AND large wing nuts on the clamps so I can tilt
it over by hand. NO TOOLS REQUIRED!			Just a friendly
suggestion. YMMV.   ;>)

Good Luck.
Best 72, 73

Michael Baker  K7DD
k7dd at cox.net

-----Original Message-----
From: antennas-bounces at mailman.qth.net
[mailto:antennas-bounces at mailman.qth.net] On Behalf Of Brian Harris
Sent: Friday, June 18, 2010 7:19 AM
To: Antennas Antennas
Subject: [Antennas] elevated radial opinions requested

I acquired a Hustler 4BTV recently and am thinking of putting it up to
complement my 135' ladder line fed dipole.  We will live in our home for a
maximum of 2 years so I don't want to knock myself out with the
installation.  

I had great past success with a 17 meter vertical with four raised 1/4 wave
radials at the 8' level so my plan is to put the 4BTV on a steel fence post
in the approximate middle of our back yard and put up FOUR 32' radials
diagonally to the corners of the yard. Like the 17 meter vertical, the
radials will be at the 8' level.  While I expect this solution will work
reasonably well, I would like to hear of the success or failure from anyone
who has done this or something close to it.  Additionally, as I can install
as many radials as I want that are less than 32' (14' would be the minimum
length), what would I gain or lose from doing so?

Thanks for your time,

Brian Harris, WA5UEK

phone 214-763-5977

email cosmophone at yahoo.com

website www.myhamshack.com/wa5uek

When they call the roll in the Senate, the Senators do not know whether to
answer "present" or "not guilty."  Theodore Roosevelt

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