[600MRG] Could my antenna be a very large Dummy Load ? - Long Reading

[Eric NO3M]

Your putting all that wire in the wrong place!  Adding more top loading 
is only going to marginally improve things.  Here's what modeling says:

30 ft monopole not top loading => 0.0945 ohms Rrad
30 ft + 4x100ft top wires => 0.367 ohms Rrad
30 ft + 8x100ft top wires => 0.383 ohms Rrad

There is almost no difference going from 4 to 8 100ft top wires. Adding 
some top wires is beneficial, but what you gain from increasing the 
amount of wire in the air is limited by your vertical's height.

As Neil alluded to, you need to mitigate ground losses.  There is no way 
around that.  Tie into anything that is buried, lay wire in out of the 
way places, some mesh fencing or screens around the base, etc.   The 
other option is make a worthwhile improvement is to increase the 
vertical height.

GL CU 630
73 Eric NO3M / WG2XJM


On 10/12/2017 12:56 PM, Andy - KU4XR wrote:
> Greetings Gents:
>
> I am beginning to wonder if I am approaching a Giant " Dummy-Load " with my antenna. I have 4 top load wires,
> ranging from 100 feet to just over 200 feet. 2 of the top wires have a termination wire connected between them.
> I estimate that I have close to 600 feet of - close to the earth ( 25' AGL ) Horizontal wire in the air, and just
> purchased another 750 feet, with the expectation of adding more top wires, and termination wire where possible.
> I will never have a Ground Radial system that will amount to anything, so nothing but mother earth underneath
> the top load wires. My Vertical height is 30 feet, and I hope to go up to 40 feet. That will be about all I can do.
> The next comments are based on watching my S-meter, and listening to background noise and believing that
> I am improving the antenna. ( I know the more vertical height, the better, but I am limited ).. Here's what I
> have noticed. In the past I had a 160 OCF up 30' AGL - strapped as a " T " antenna. It was as noisy as a nascar
> race. The short leg, went across the powerline service entrance - tied off to a tree. Constant powerline buzz.
> I decided to tie the center, and shield of the coax together at the dipole, and bend the short leg in another
> direction - away from the powerline. Instant reduction in line buzz ! - AND - reduction in received signal
> levels also. A previous question on this list informed me that powerline coupling effect is an issue, thus
> the loss in received signal strengths when I moved the wire away from the powerline. But not living with
> a constant 20 over S-9 line buzz was worth a reduction in signal strength. The S-meter dropped to S-9 after
> moving the wire. No noticable change in the needed L  to peak the antenna. I added a 3rd top wire,
> and right away saw a difference. After adjusting for Less - L ; the S-meter was resting on S-8. Signals
> on 630 meters got better. Later on, I added a 4th top wire. This one unfortunately is running at a heavy
> sloping angle and is very close to earth over much of its length. Another instant change ! After adjusting
> for less - L ; the S-meter was resting around S-6.5 to S-7. What was the short leg of the OCF was
> lengthened to within 3 feet of the pine tree limb it is tied off to, and I connected a termination wire from
> it, over to the heavily sloping wire ( 65 feet ). This is what I have in the air at the moment.. After adjusting
> for Less - L again, my S-meter is now resting on S-5, and bouncing up to S-6.5 on peaks. I have not been
> using a Shunt element until just the past 3 weeks or so. Through experimentation; I added a Shunt - LC on
> the radio side of the loading coil and after adjusting; the S-meter rose 1 S-unit on resting noise and now
> rests at S-6.5 and bounces to S-7.5 on peaks. The level varies due to neighborhood noise makers, and when
> it is " dead quiet " , the S-meter rests at S-5, and bounces to S-6.5, BUT, that is not the norm unfortunately.
> Here are my present values - measured as best I can do. (( Starting point was the OCF at 30' AGL, and
> 260 feet top load... I used 152 microHenries of coil with no shunt element ( my oversight there ). ))
> The present setup is 30' AGL Vertical APEX, with very close to 600 feet of top load wire going in 4 directions,
> and varying land slopes. My Series " L " is 82 microHenries, and the Shunt LC on the radio end of the coil
> is 93 microHenries - L ( Fixed ) , and 1,142 pF - C ( Air Variable ) . Of course, Dryground - Wet ground does
> affect the tuning. *** NOW The Big Question for me is: with all the losses over earth - no radials - and
> everything else lossy that can be factored in; when I eventually try to put RF into this Monstrosity; will I
> possibly be transmitting into a Very Large - Dummy Load ? It Hears, and pretty good in my opinion, but,
> that doesn't mean it will radiate RF in the same fashion. My hope is to add 3 more top load wires, and
> terminate the ones that can be. I am starting to wonder if this may be an exercise in futility.
> Thanks for reading this, and comment if you wish - on the list might be good - for others to benefit from it.
>
> 73: Andy - KU4XR Friendsville, TN. - EM75xr
>
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