[Elecraft] The "Kinda Random Antenna"

[Barry]

Bill,
     There are many factors that could impact on his system 
effectiveness. The one that most comes to mind is height above ground. 
160 meters can be a real problem. If it is a horizontal, the average ham 
antenna height of 35-50 feet is very, very low electrically. Two things 
would happen here. First, a lot of energy is being lost to ground, and 
second, the radiated signal will be at high angle. Remember, a quarter 
wave on 160 meters is on the order of 135 feet which is the point where 
you get maximum radiation straight up. At lower heights, gains upward 
goes down and doesn't fill in toward the horizon. The means electrically 
low antennas are not effective.

     The other area that comes to mind is the feed system itself. Not 
mentioned is whether open wire is being used. I would guess that the 
system SWR may be very high meaning losses on coax should be much 
greater than a 1 db. And, some tuners are not low loss when operated at 
their extremes.

     I get away with what I do ONLY because my 20 meter vertical antenna 
is less effected by being low, I feed it with ladder line which has low 
loss even at absurdly high SWRs, and the tuner I use is designed to be 
used with antennas that are no where near optimum.

     From what I did this weekend, I could surmise that my 33' radiator 
was radiating everything it received. If there is someone who really 
wants to do a math problem, I'll measure exactly the transmission line 
length, but I suspect that basically the about 60 feet of open wire 
helped. I would guess that the antenna reflected a very low impedance 
with a large reactive component, and the line length helped in 
translating the antenna impedance to something better handled by the 
tuner. Therefore, my losses are contained.


73,
Barry
K3NDM

------ Original Message ------
From: "Bill Johnson" <k9yeq at live.com>
To: "'Barry'" <k3ndm at comcast.net>; "'Emory Schley'" 
<silverlocks at gmx.com>
Cc: "elecraft at mailman.qth.net" <elecraft at mailman.qth.net>
Sent: 1/30/2017 9:42:35 PM
Subject: RE: [Elecraft] The "Kinda Random Antenna"

>OH YES,  the headaches from looking at the formulas at this stage of 
>the
>game. A friend added two coils to the end of his 75 meter dipole for 
>160.
>He loads it but has no clue as to impedance and loading.  He tunes it 
>for
>160 but it is not effective.  The idea is to get loading into an 
>efficient
>radiator.  OK to accept less to operate, but great to be efficient.  SO 
>if
>it is working, sometimes leave it alone.  Erect another before taking 
>down
>or modifying what works.
>
>73,
>Bill
>K9YEQ
>
>-----Original Message-----
>From
>
>Yep. A good antenna tuner and ladder line hides a whole lot of stuff.
>Where would I be with my 40' X 110' yard if I really worried about 
>being
>exact. I have DXCC mixed, CW, and SSB, and I never ran over 100 Watts 
>nor
>had a real "resonant" antenna. And, I've forgotten all of the math I 
>ever
>had in college more than 50 years ago; I get a headache when I think of 
>ever
>having to do math again.
>
>73,
>Barry
>K3NDM
>
>------ Original Message ------
>From: "Emory Schley" <silverlocks at gmx.com>
>>
>>I've found over the years that a McCoy Dipole works pretty well, often
>>MUCH better than expected. What is a McCoy Dipole? Named after Lew
>>McCoy, it follows his rules of construction. "Make it as long as you
>>can, get it as high as you can, and feed it with ladder-line." No 
>>math,
>>no measurements, no sweat. But a TUNER (transmatch) is definitely
>>needed.
>>
>>Emory Schley
>>N4LP
>>
>>
>>Kurt N. Sterba was correct. Textbook antennas aren't always
>>possible, or even needed. If the situation is difficult, any radiator
>>is
>>better than none. However, hams in general are anal animals on the
>>subject of antennas. My attitude has always been what's a db or two
>>among friends, and quite often that is the number we are sweating. 
>>But,
>>if you can't make it exactly like Kraus writes, get as close as you 
>>can
>>and let your antenna tuner worry about the match and don't think about
>>that extra db.
>>
>>73,
>>Barry
>>K3NDM
>>
>>------ Original Message ------
>>From: "Fred Jensen" <k6dgw at foothill.net>
>>
>>>N6BT famously set up a "phased array" of 3 light bulbs in a V-beam
>>>configuration and achieved WAC. He called it "The Illuminator." Kurt
>>>N. Sterba [a regular in the old WorldRadio] is correct, the power 
>>>will
>>>go somewhere. My home antenna is a 136' wire strung along the wood
>>>fence on electric fence insulators. Fed at the end, no overt
>>>counterpoise [the outside of the coax shield handles that]. Not 
>>>spec'd
>>>for 160 but the KAT3 matches it fine. Invisible to HOA. NVIS on 160
>>>and 80, semi-NVIS on 40.
>>>
>>>One thing to remember: feeding electrically long wires results in
>>>complicated radiation patterns. The higher in frequency you go, the
>>>more it's going to squirt your RF in different directions, not all of
>>>which point at the DX. But, mine works very well considering it's
>>>about 1.8 m off the ground.
>>>
>>>73,
>>>
>>>Fred ["Skip"] K6DGW
>>>
>>>On 1/29/2017 10:26 AM, Barry wrote:
>>>>Wayne,
>>>>   I know what you are saying and agree. In very simple terms, if you
>>>>can load it, it will radiate. That was a position that a writer with
>>>>the nom de plume of Kurt N Sterba too in a book he wrote. By the
>>>>physical law of conservation of energy, it all has to go somewhere.
>>>>And, that could be heat or radiation. In his book he claims to have
>>>>loaded a shopping cart and talked to people.
>>>>
>>>>   Yes, you can do these things as long as you make good connections
>>>>and the tuners can handle it. All of the discussion is how to pick a
>>>>length that the tuner will accept. Once there, physics takes over.
>>>>And
>>>>just to prove my point, and yours, I just worked the CQ 160 CW
>>>>contest. My antenna was a vertical 20 meter dipole center fed with
>>>>open wire. My radio is a K3s. I worked across this country, Canada,
>>>>and some DX with this 33' wire antenna that by all rights should 
>>>>have
>>>>been over 200'. I would have done better, but my local power company
>>>>added another handicap, line noise. Bottom line: Throw some wire up
>>>>and see if it can be loaded. If yes, go for it.
>>>>
>>>>73,
>>>>Barry
>>>>K3NDM
>>>