My newest creation

  • Thread starter Lawless
  • Start date
  • Replies 7
  • Views 430
L

Lawless

Guest
OK, here it is, a heavy duty 2m antenna suitable for outside mounting and wind and stuff. Just a 1/4 wave ground plane but tough.

I took a flat aluminum bar and bent a 90* on one end and drilled a 1/2" hole so a regular 3/8s antenna stud would go in it. I took four 1/4" aluminum rods (20") and used those aluminum brazing rods (like seen on TV) and attached them for the ground plane. Bent them down at 45*.

Then installed the stud stuff (with a stainless star washer) and cut an old stainless CB whip at 19.5" (including stud) and put it all together.

I primed it and painted it black for stealth.

I have to say, I like it and it was practically free. Gonna put it on top of my flag pole and see how it works.












 
Last edited:
If you were to build a square box of your .25" rod and and "gusset" the legs to one another would that effect signal? If I read the post correctly the legs are just the ground. I really like the "homebrew"!
 
cjcullom said:
If you were to build a square box of your .25" rod and and "gusset" the legs to one another would that effect signal? If I read the post correctly the legs are just the ground. I really like the "homebrew"!
Click to expand...
That is a great question. @htperry @RFMan @JohnFreeman
I think not, they will just be floating in space, no load once the center flat bar is mounted to a mast so it is not needed from a strength standpoint.

I have it connected to a spare piece of 8x and it works wonderfully.
 
That's right; the legs are ground. The square box gussets would not help the ground work any better, because image currents flow in the ground (in the legs in this instance) radially from the vertical element (along the wire legs). They don't want to "slosh around" back and forth (leg-to-leg). Even if the ground plane were a flat disk...current would still flow radially (since the rod is a cylinder). That's why you can take a solid disk ground and slice pie-shaped pieces out of it, turning it into a bundle of wire spokes, and get the same performance. More spokes (or wires) more closely approximates a solid ground plane. Those quarter-wave ground plane antennas with a vertical wire and three or four ground legs are really good antennas: easy to build and very efficient.
 
Looks good! That's a nice looking GP. It'll work great for your home station purposes.

Mathematically there's undoubtedly a difference between the legs and legs with more spokes, etc, but in any practical sense you'll never notice and increase over what is shown here. Think of the "legs" as the other half of a dipole....the roof of a car cut into strips and bent down , etc.

Paul, that should give you nice low angle radiation and is bulletproof. Good job!
 
JohnFreeman said:
Looks good! That's a nice looking GP. It'll work great for your home station purposes.

Mathematically there's undoubtedly a difference between the legs and legs with more spokes, etc, but in any practical sense you'll never notice and increase over what is shown here. Think of the "legs" as the other half of a dipole....the roof of a car cut into strips and bent down , etc.

Paul, that should give you nice low angle radiation and is bulletproof. Good job!
Click to expand...
Maybe I was being fuzzy...the difference between 3 or 4 spokes and MORE spokes is for sure low; no practical difference; no issue there. I was not suggesting adding more "spokes." You would need a high-$$ antenna range to measure the difference because it's so small.

I was talking about adding more metal BETWEEN the spokes (gussets). They don't help at all, because there are no transverse (along arcs of circles) currents.

I do like it; have made a few myself!
 
You must log in or register to reply here.
Back
Top Bottom