Add a loop of string to the top and hang it on a tree branch use it with your handheld transceiver then roll it up.
Roll up j pole antenna plans.
J pole antenna design.
The slim jim designed by the late fred judd g2bcx can be a great portable roll up antenna if made out of 300ω or 450ω ladder line twin feeder.
Dbj 2 ham dual band roll up antenna kit 144 148 mhz and 440 450 mhz includes adapters for bnc sma and sma female.
Try adding a balun to the coax.
Shield attaches to the short section feed point.
Harris a vhf uhf 3 and mobile antenna qst feb.
Enter the operating frequency.
3 ounces compact and effective.
To wit figure 3 shows the e plane gain along the plane through the roll up j antenna and the mast of figure 2.
When rolled up it is an extremely compact pocket sized antenna.
Fong us patent 9 608 336 radial free ollinear omni directional triband antenna edison fong august 25 2015.
This simple antenna lends itself well to emergency use or as a portable antenna for hotel room operations while traveling.
Figure 3 ladderline j pole with and without feed line choke for the purists and since it matters in this discussion the view above is from the other side of figure 2 antenna and feed line are to the right of the mast.
What can i do.
This calculator can be used to design a slim jim or a j pole antenna.
Design your j pole for hf 2 meters 220 440 and up.
There are several features which make the ubiquitous twinlead j pole antenna a good addition to your emergency grab n go kit.
A portable vhf uhf roll up j pole antenna for public service edison fong wb6iqn.
Also includes a 6 ft extension cable.
Maximum power input 50 watts.
The 2 meter roll up j pole is lightweight approx.
A portable vhf uhf roll up j pole qst march 2007 vol.
To a portable roll up antenna.
91 no 3 pp.
Save time by using the calculator below.
Fong us patent 8 947 313 radial free ollinear.
A balun is necessary because a j pole antenna uses a balanced feed the.
Unlike the popular ground plane antenna it doesn t need ground the dbj 2.
Coax center conductor attaches to the long section feed point.
The antenna can be set up quickly and easily by hanging out a window attach to a ceiling or toss a lead sinker over a tree branch with kite string and hoist it up.
Since it is the second version of this antenna i call it the dbj 2.
Principles of the dbj 1 the earlier dbj 1 is based on the j pole 2 shown in figure 1.
I built the dual band j pole antenna from the article in the september 1994 new ham companion an easy dual band vhf uhf antenna page 61 but i just can t get it to work.
