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

Sat Sep 1 10:23:33 EDT 2018

I played with the loop calculator at the link that you provided.
Got some impractical results:diameter 90.5 feet  ( I used a length of 300 ft which was in the range they suggested)
conductor 0.9 inchQ= 497 !!!!BW = 1.27 KHZCap voltage = 5000 volts RMS
Even with a conductor almost 1 inch in diameter , the Q is 497 and the BW is 1200 HZ1) 90.5 foot diameter ? how does one build and install such a structure?2) How does one tune ( and keep tuned) something with a Q of 497? Servos with continuous feedback?
I thought the whole thing was "loopy"
   On Saturday, September 1, 2018, 9:37:42 AM EDT, Dave Riley <dave.riley3 at verizon.net> wrote:  

  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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