[600MRG] More 630m antenna efficiency...

[Dave Riley]

It's fun to see the banter and playback all around... Termination of 
this discussion ended up around 1.65/1 SWR, ( self written results ) ...
Brain food, that's all it is, and maybe a good antenna...

Now for the next batch of toil and trubble to wrestle over...

I am a confirmed loopest and have sworn NEVER to divert ANY RF in to a 
lossy ground system... EVER...
To that end I promise to keep all power possible in the LOOP, as it 
were... Enuf of it gets lost in the ground as it stands already...

The next personal challenge here is to arrive at the possible EIRP from 
this loop, 5W eirp for the very least RF power input...
Right now it is costing me about 13 watts in order to claim 5W eirp +/-...

I started out with a monster dog wire loop 630m antenna made from e-bay 
for very cheap $$ and I was astounded by how simple a single wire 
antenna on our new band could perform...
I only added a good vacuum variable cap. in series and used a good mix 
for the Ferrite coupling transformer...

I use this small loop transmit formula which may or may not be the best 
bottom line in computation...
http://www.66pacific.com/calculators/small-transmitting-loop-antenna-calculator.aspx

I am now at the stage of trying to increase the wire diameter from #14 
stranded copper to something larger for cheap money and lots of gain, 
say 1/4"...

Here is what I have up now:
450' circumference loop, using double CATV RG6a coax with a copper runner...
https://www.ebay.com/itm/Directv-Dual-Black-CR03BDR0-05-Ground-RG6-Coax-Cable-on-EnviroReel-ReeLogic-Reel/163202369537?hash=item25ff9e8801:g:WRgAAOSwc2FaLfFs

It is lightweight, contains 5 separate conductors, and when paralelled 
together must add up to something more than .25" diameter or so...
Maybe today I will measure say 25' of each wire on the RF bridge and 
report back...
Below is a 'rac' table taken from Bill Ashlock's work as my starting 
point of reference;

We read in the book of Bill's, the efforts derived from the following;
ConductorType   Rac ohms        Tot Rac ohms
#12 awg          1.15    1.37/1.48 0.83/.80      0 db     ** Reference 
start point...
#10 awg          0.92    1.14/1.25 0.91/.87    +0.8 db
#8 awg           0.72     .92/1.03 1.02/.96    +1.8 db
#6 awg           0.57     .79/.90 1.09/1.03    +2.4 db
#4 awg           0.45     .68/.79 1.18/1.10    +3.1 db
#2 awg           0.36     .57/.68 1.29/1.18    +3.8 db

#12 x 4          0.32    .55/.66  1.31/1.20       +4.0 db
#12 Litz         0.57    .79/.90  1.10/1.03       +2.4 db
#12 Litz x 2     0.30    .59/.70 1.27/1.16      +3.7 db
#12 Litz x 4     0.16    .38/.49 1.58/1.39      +5.6 db
RG-8/11          0.38    .60/.71 1.26/1.16      +3.6 db
½” Cu pipe       0.15    .37/.48 1.60/1.41       5.7 db  **** BEST by 
far  LOWEST a.c. 'R' measured

This table is based on Bill Ashlock's testing @ 185kc. and a 200' 
circumference square loop... 50' on a side...

My question now is what will the RAC be of the 5 separate RG6A 
conductors wired together in parallel???  I guess @ .4" equivalent 
diameter +/- for;
Antenna efficiency: 34% (-4.7 dB below 100%)
Antenna bandwidth: 2.07 kHz
Tuning Capacitance: 622 pF

Capacitor voltage: 1,573 volts RMS
Resonant circulating current: 2.92 A
Radiation resistance: 0.402 ohms
Loss Resistance: 0.772 ohms
Inductance: 181 microhenrys
Inductive Reactance: 539 ohms
Quality Factor (Q): 230
Distributed capacity: 369 pF

Antenna "circumference": 450 feet

That is with one copper wire carrier, two solid shields of 75 ohm coax. 
approx .240" each, and two center conductors ( copper ) #18 or so...

It is very tempting to go to Lowe's and buy 10' sections of 3/4" 
schedule 'M' copper pipe!!!  Am resisting...
It is already too easy to make 5W eirp from the low power transverter 
here... Why re-invent the wheel??

Comments??


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