Hi Gang, Some folks mentioned that the top yagi is not "seen" on my short tower if I should shunt feed it. Is there any proof of that? Papers? EZNEC? Anecdotal evidence etc? (like you removed the top
Mike, with the bottom Yagi only the modeled tower resonant frequency is 2.6 MHz. With the top Yagi added the resonant frequency is 2.0 MHz. The current is uniform along the first 48' and drops to one
Hi Mike, I have a similar height mast (military AB-621) with a somewhat larger antenna on top, 4 El. SteppIr. When K6SE was still alive I discussed shunt feeding it with him. Earl thought it could be
Anecdotal: In the 1980s, I had a 100-foot Rohn 25 shunt-fed tower with 200 radials. On top was a 204BA (4-el Hy Gain 20m yagi). The mast extended 12 feet above that. Later when I added a 4-el 15-mete
Years & years ago a learned & wise old Ham radio sage & friend of mine once said that ANY tower--capped with a beam up top, or not--will ALWAYS be 50% taller ELECTRICALLY than it is PHYSICALLY. I've
Using EZNEC to do some quick model comparisons - looking for trends and not exact values - the effect of a higher antenna depends on the relative sizes and separation. If the bottom antenna is much
Author: Pete Michaelis - N8TR <pete.n8tr@gmail.com>
Date: Tue, 10 Nov 2009 12:31:55 -0500
My experience is similar. I have 100' of Rohn 45 shunt-fed at 60' with about 50 radials. When I first installed the shunt feed it had a a 40-2CD ft at 108' and a KT34XA at the top of the tower. When
All the reading and discussions I have over the preceding 6 years suggest In going up the tower to various conductors, the current tends to pick the LONGEST conductor path "near" the top for the grea
Fascinating information on stacked antennas for a shunt fed tower but....... in my case I lost my A4 Tribander after Hurricane Omar but the 85 foot Rohn 45 remained intact. So I ran up a 35 foot alum
This has been a very interesting thread and one that I took notes on. I will have a new system going up that will be 120 feet of Rohn 45 tower with large yagis at 60 and 120 feet - 48 ft. booms. I do
Somewhere in the distant past I heard or read a rule of thumb that said the top loading contribution of a yagi was about 1.8 times the turning radius it the antenna was relatively "square." That is
Tony, As shipped all of the MonstIR elements are floating. You see a change in resonance because of the coupling via the coax shield to one side of the driven element. That effect is very difficult t
There is a toroidal "balun" inside the drive motor enclosure for my 3-el SteppIR. This won't do much on 160M, but you can add a coaxial common mode wound on ferrite cores at the antenna feedpoint. If
Since the drive element connection for an HF yagi or 80/40 meter dipole tends to be at a HIGH Impedance point when the tower is shunt fed, the typical common mode choke - even one with 3 - 5K chokin