Next project - Mag Loop Antenna VU3GAO

This is the next antenna I'm building. The only piece I need is the variable cap. I plan on making the frame from PVC that fits in my tripod and making it remote tune-able 

I'm grabbing this now as we all know how the life expectancy of a tripod website. Remember geocities, 

PDF here

 ----------------------------->8 Clipped from website 8<-----------------------------

UPDATE: Math from 66Pacific which I will try first before committing to the original design I found. I'll make a second loop to get me 80m and if it fails then build another 40m and sell it as such.

Antenna efficiency: 36% (-4.4 dB below 100%)
Antenna bandwidth: 15.4 kHz
Tuning Capacitance: 122 pF

Capacitor voltage: 2,912 volts RMS
Resonant circulating current: 15.6 A
Radiation resistance: 0.074 ohms
Loss Resistance: 0.132 ohms
Inductance: 4.25 microhenrys
Inductive Reactance: 187 ohms
Quality Factor (Q): 454
Distributed capacity: 16 pF

Antenna "circumference": 20 feet

Loop antenna Side length: 2.50 feet

Antenna diameter: 6.0 feet

OCFD Windom Antenna

Well I revisited the inverted v dipole I had previously made and with the help of a couple of calculators came up with an off center feed dipole. But this time instead of cutting my wire to the length required I started from the terminals of the 4:1 jetstream balun to the receiving part of the dogbone.  One element 23' 2" 3/8 and the other element 46' 3" 5/8 and holy smokes what a difference. 40m, 20m and 10m I get 1:1 SWRs. Which really doesn't mean much as my can-o-dummy gets 1:1. I haven't had a chance to test it's range. Nor have I plotted it in MMANA. This was just an impulse brain fart. But I calculated 1/3 wave for 7.074 and doubled that for the other side. Before that I was trying to find a happy middle between digital and phone, but that's a difference of 3 feet from end to end. And neither side feeling the joy of resonance. So since I do more digital I sided with the lengths for digital modes. I may fire up the smelter furnace and do some lost PLA casting to make an octopus antenna using ham stix this summer for my next project.

Read more: OCFD Windom Antenna

Cheap 40m Dipole

There are probably cheaper ways of doing this, but I had these parts on hand.

  • 2 section of fence top rail
  • 1 antenna mounting bracket
  • 1 little pulley
  • 1 make shift hanger for the top to hold the pulley
  • All the above can be substituted with a tall tree or a pair of them, or more for even kewler antennas. 
  • 66 feet of 14 THHN Stranded wire or anything really. You could use nylon coated wire rope. Just factor in the velocity spec which may be a foot in one direction of the other. I already had a 500 foot spool, and I didn't use any of that. I took all the short pieces I had and soldered them all together to make a pair of 33's. Don't run your hand down these bad boys.
  • And the magic of it all is a Jetstream 4:1 Balun that keeps it all happy. Calum M0MCX has a nifty SWR calculator for excel to dial it in.

That's pretty much it. Mine is up 6.5m in the middle and 3m on each end. You will need a tuner with it. Should be close to 1:1 on 40m though. If you had two 51 foot lines and 30-34 foot of ladder line you'd have a G5RV or two 25.5 foot pieces and 15-17 feet of ladder a G5RV Junior. Neither of the last two require a balun. Ugly balun yes or a bunch of ferrite beads as you can almost see in the picture by the balun.

Read more: Cheap 40m Dipole

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