MilAir Antenna from ST-2 Design

[w4rtt]

1/2" OD - 3/8" ID square tube, no need for a mill

How do you cut a flat bottom channel without a mill?

 

[w4rtt]

1/2" OD - 3/8" ID square tube, no need for a mill

How do you cut a flat bottom channel without using an end mill?

Randy

 

[digitalanalog]

end mill the insulator for the stiffener tube yes.

 

[digitalanalog]

OK, need a mill for that. Might get by with a drill press. Got plenty of UHMW to play with.

Randy
W4RTT

Are you planning on building an antenna like this?
Can't wait to see the out come.

 

[w4rtt]

Yes, had a couple over the years and they worked well. I've rounded up the aluminum and UHMNP, so I have to BBS a table top band saw to cut the Poly. Ebay has all kinds of the stuff. Still deciding which version I want to make though.

Randy W4RTT

 

[w4rtt]

The frequency range is 225-400Mhz. Did you just divide the range by 3 and make the 3 full wave dipoles to those dimensions?
I'm getting closer to putting one of these things together.

 

[Ubbe]

...and make the 3 full wave dipoles to those dimensions?

Never use fullwave as those are very high ohm at their ends and have a strange directional pattern. One element should be a 1/4 wave and the other one a 1/4 wave which makes it a 1/2 wave dipole. You can experiment with 5/8 and 3/4 wave elements that have a better matched low impedance at their feedpoints.

/Ubbe

 

[w4rtt]

Never use fullwave as those are very high ohm at their ends and have a strange directional pattern. One element should be a 1/4 wave and the other one a 1/4 wave which makes it a 1/2 wave dipole. You can experiment with 5/8 and 3/4 wave elements that have a better matched low impedance at their feedpoints.

/Ubbe

He clearly states at the top of the page where he describes the antenna,
"Each element was cut to a specific 1/2 wave length in the spread of 200-400MHz range.
all elements are of different lengths and cut as mentioned to 1/2 wave length dimensions
instead of the typical 1/4 wave length. " So, are these 1/4 wave clusters or 1/2 wave clusters.

Randy W4RTT

 

[digitalanalog]

they are cut at 1/2 wave lengths, not divided by 3 as you asked, i broke down the range and selected 3 higher edges a 3 lower edges of the band spread, the center of the band spread was not used just 3 points upper band and 3 points lower band. that's how it did it, you can play with the numbers to suite your ideas. Remember, it is a home made antenna. other may disagree but mine works just fine for now.