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Technical Topics => Equipment => Topic started by: NJQA on April 08, 2020, 1329 UTC

Title: L band antennas
Post by: NJQA on April 08, 2020, 1329 UTC

Some good construction info here for L band antennas:

http://www.merseyradar.co.uk/airband-radio/l-band-diy-antennas-for-jaero/

Title: Re: L band antennas
Post by: ThaDood on April 08, 2020, 1832 UTC

Hmmmmmmmmmm, with some modification, that looks like it could be a decent 1.2GHz design for 1296 SSB in Amateur Radio.   

Title: Re: L band antennas
Post by: chanito on April 08, 2020, 2124 UTC

Nice antenna the 3d printed part one. Pretty sturdy.


I've found JAERO, Fleetnet, Safetynet all come in fine on an indoor antenna here in S. Texas.


I built these out of nothing more than cardboard, paper, aluminum foil, foam and some copper tape. They just sit there on top of an equipment rack pointing at the ceiling.

(https://i.imgur.com/Z0bxq1L.jp)

[/size][/color]

(https://i.imgur.com/q3axg1n.jpg)

[/size][/color]

(https://i.imgur.com/U7X5kI0.jpg)

[/size][/color]

(https://i.imgur.com/KVFtFOb.jpg)

[/size][/color]

(https://i.imgur.com/c3H7XeG.jpg)

[/size][/color]

(https://i.imgur.com/fB91g6O.jpg)

Title: Re: L band antennas
Post by: ThElectriCat on April 09, 2020, 0405 UTC

If you are feeling ambitious
http://lea.hamradio.si/~s53mv/wumca/cavity.html
these are some nicely built antennas

Title: Re: L band antennas
Post by: Brian on April 10, 2020, 1909 UTC

Quote from: ThElectriCat on April 09, 2020, 0405 UTC

If you are feeling ambitious
http://lea.hamradio.si/~s53mv/wumca/cavity.html
these are some nicely built antennas

I get a security warning from Chrome when I visit that site!

Title: Re: L band antennas
Post by: ThElectriCat on April 11, 2020, 0408 UTC

Sorry guys, I didn't get that message originally, but if I use chrome it shows up.
I have been looking at this guys website for years, and I doubt that the posting is legitamate, but its probably best to play it safe.
https://imgur.com/EtzwGm5
Here's the drawing of the antenna, The designer (and owner of the problematic website) is Matjaz Vidmar, S53MV. credit for the drawing goes to him, not me.

Title: Re: L band antennas
Post by: Pigmeat on April 11, 2020, 1527 UTC

I remember that guy because we were always discussing LPAM as it wasn't legal where he lived.

Title: Re: L band antennas
Post by: jasmine on April 15, 2020, 2005 UTC

Quote from: chanito on April 08, 2020, 2124 UTC

Nice antenna the 3d printed part one. Pretty sturdy.


I've found JAERO, Fleetnet, Safetynet all come in fine on an indoor antenna here in S. Texas.


I built these out of nothing more than cardboard, paper, aluminum foil, foam and some copper tape. They just sit there on top of an equipment rack pointing at the ceiling.

(https://i.imgur.com/Z0bxq1L.jp)

[/size][/color]

(https://i.imgur.com/q3axg1n.jpg)

[/size][/color]

(https://i.imgur.com/U7X5kI0.jpg)

[/size][/color]

(https://i.imgur.com/KVFtFOb.jpg)

[/size][/color]

(https://i.imgur.com/c3H7XeG.jpg)

[/size][/color]

(https://i.imgur.com/fB91g6O.jpg)

i would love to try to build this antenna. do you have a step by step guide for a person totally new at this?

Title: Re: L band antennas
Post by: Josh on April 16, 2020, 2016 UTC

These are nice if you don't want to roll your own;
https://www.rtl-sdr.com/preorder-sale-active-l-band-1525-1637-inmarsat-to-iridium-patch-antenna-set-for-34-95/

Title: Re: L band antennas
Post by: chanito on April 17, 2020, 1944 UTC

Quote from: jasmine on April 15, 2020, 2005 UTC

i would love to try to build this antenna. do you have a step by step guide for a person totally new at this?

For the square 'patch' type I just used some modified dimensions from the that Youtube project at the bottom of the  http://www.merseyradar.co.uk/airband-radio/l-band-diy-antennas-for-jaero/. He gives the dimensions. I just did it with cardboard and foil instead of aluminum. The spacer is a thin foam I had lying around.


The helical antenna is just math and craft, using the helical antenna calculator here: https://www.daycounter.com/Calculators/Helical-Antenna-Design-Calculator.phtml


The feedpoint is 1mm off the aluminum foil backplane. The copper tape can be found on Amazon or at Hobby Lobby. Double sided Scotch tape is useful as well for some of the construction.


I have the actual print file for the sheets of paper somewhere. I'll see if I can dig it up and post.


It does work surprisingly well. Screen grab from today. Using SDR# with the Scytale-C plugin you can see the 1537.700MHz NCS44 channel (Fleetnet&Safetynet) and some adjacent FSK streams:




(https://i.imgur.com/44SkWzm.jpg)

Title: Re: L band antennas
Post by: chanito on April 18, 2020, 1306 UTC

Here's the paper template https://www.dropbox.com/sh/ydce3kx00w3sz5x/AAB9E3PEsEa8BVBx5jPNFb8Fa?dl=0


This print uses 4 sheets instead of 3. you have to print full page no borders, 'fit to page'.