2 element beam for 20 meters from gw0jxm
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This is post 2336 in a continuing series of simple ham radio antennas.
Do you want an antenna with modest gain that works in both directions? Then, perhaps, a modified W8JK 2-element beam will fit your requirements.
Thanks to Andy (GW0JXM) for this fairly simple 2-element 20 meter beam that is bidirectional broadside to the elements. You may work both long and short path with out major adjustments to the antenna.
Here are some general comments from the author:
At the end of the video I show a sketch of the dimensions and the costing for the materials for the elements and the mast. The costs, in pounds sterling, are as of July 2011
The swr is 1.11:1 and the 1.5:1 band width of around 260Hz
I'm sorry I've mixed metric and imperial measurements but that's what I've grown up with.
When weighing the beam at the mast head with the mast horizontal and the bottom of the mast still on the ground it weighs 30 pounds (13.5 Kg) The effort to pull it upright is more than three times that when I'm standing 7ft above ground level. So if you had to pull it up while standing at ground level it would require considerably more effort. If you're really keen to build one you could always pull it from an upstairs window Hi Hi.
Update ... I've looked at the uploaded video and I see I've missed off showing you the length of the gamma rod, coloured green on the sketch. It's a 15mm diameter copper tube that's 39 inches long.
If you want any more details just ask and I'll try and answer your questions.
I'm not making any claims for the 'gain' as it's early days for the antenna, all I can say is I believe that I have been able to get on top of a couple of pileups that I would have struggled with on with my 20 metre inverted 'V'
I will, hopefully, soon be making another video in which I will go into the setting up of the gamma match and give you some better pictures of the connections.
Update I've been asked the weight of the aerial so here are the details.
The driven element with the central fixing plate, 'U' bolts and gamma is 12 lb
The reflector and its fixing plate and 'U' bolts is 8 ½ lb
The boom with its fixing plate and 'U' bolts is 5 lb
And the mast as shown in the video weighs in at 14 lb
Please let me know if you find this helpful or interesting.
Update... May 2013 Here's a link to another video relating to this antenna that I made two years after I made the original video it's titled 'About Radio 68 A little bit of antenna maintenance' http://youtu.be/-Kbp8eFbhL0
Thanks for watching.
Kind Regards .. Andy gw0jxm."
Thanks for joining us today.
Aloha es 73 de Russ (KH6JRM).