How did you get the trap on the drawing? I need to learn how to use this program and in your presentation you just jumped to the trap already drawn in .
It is inspired by the DBJ-1 antenna published by Ed Fong in QST www.arrl.org/files/file/Technology/tis/info/pdf/0302038.pdf . He used 300 ohm twin lead where the stub is shorted and snipped RG-174, see figure 3. I converted it to a copper pipe design and optimized it. The stub works both ways, down or up. I chose down to keep the rain out.
My friend I just found your video and guess what, I just finished the same thing and about to start checking out other paremiters of this antenna . I put a 3/4" copper pipe sleeve over the 1/2" to do the same thing and is works great but I hadn't had time to realize that it's a collinear dipole at uhf , nice, so we have gain now on uhf and a great half wave at vhf . I saw where a gentleman got a patent on an improvement on the j-pole antenna by adding 1/4 wave chokes to bottom of mount , I think to improve Omni characteristics . I had built sleeve chokes for my antennas but on this one my dual band choke didn't work right .
It is sold as 1/2 inch, but I just measured mine with calipers and it was 16.0 mm. That is slightly off 12.7 mm (1/2 inch) but it shouldn't make much difference once the antenna is tuned.
Fantastic job amigos! 73 de KC3PRI
How did you get the trap on the drawing? I need to learn how to use this program and in your presentation you just jumped to the trap already drawn in .
It is inspired by the DBJ-1 antenna published by Ed Fong in QST www.arrl.org/files/file/Technology/tis/info/pdf/0302038.pdf . He used 300 ohm twin lead where the stub is shorted and snipped RG-174, see figure 3. I converted it to a copper pipe design and optimized it. The stub works both ways, down or up. I chose down to keep the rain out.
My friend I just found your video and guess what, I just finished the same thing and about to start checking out other paremiters of this antenna . I put a 3/4" copper pipe sleeve over the 1/2" to do the same thing and is works great but I hadn't had time to realize that it's a collinear dipole at uhf , nice, so we have gain now on uhf and a great half wave at vhf . I saw where a gentleman got a patent on an improvement on the j-pole antenna by adding 1/4 wave chokes to bottom of mount , I think to improve Omni characteristics . I had built sleeve chokes for my antennas but on this one my dual band choke didn't work right .
Thanks for the comments!
Are J-pole’s. Directional ?
No. Jpoles are omni-directional.
Hello sir! what is the diameter of the copper tube?
It is sold as 1/2 inch, but I just measured mine with calipers and it was 16.0 mm. That is slightly off 12.7 mm (1/2 inch) but it shouldn't make much difference once the antenna is tuned.
Hello! How can I contact you?
Hi Ринат Дыбов - You can email me direct. My address is good on QRZ.com, my call sign is KB3EOF.