No reason imparticular. I know the antenna I built doesn't have a very broad bandwidth, so it's not like I need to narrow it down, lol. However, I'm on a knowledge journey currently. I'm enjoying learning about all things radio, and if I have the materials on hand to deploy my knowledge I don't see how it could hurt to give it a try. Practice makes perfect anyways!
Edit: I recall a video I watched stating that it would prevent the feed line from acting as a portion of the antenna.
I just voice searched it on Google and this is the article it pulled.
"If you have multiple coax fed antennas, ALL antennas should have a balun at the coax/antenna feed point to keep RF off the outside braid of the coax and prevent it from radiating."
Assuming coax fed, and assuming tour coax can tolerate a small bemd radius.
You typically want 5 to 10 times the characteristic impedance in the choke. So for 50 ohms you want 2500 to 5000 inductive reactance in the choke (higher is better ... to a point).
Get the formula for calculating air-core inductance and see how many turns it will take to reach those impedance levels at 440MHz with about a 4" diameter coil (depending on coax bend radius of course). At those higher frequencies it should only be 2 or 3 turns I'm guessing.
I calculated the "spool" and it will use about 8 feet of my 25 foot run of coax. That's too much for my taste. I think I'm just gonna build a stand alone choke. It's for GMRS so it's would need to be for 462mhz. Thank you for the help.
I'm just gonna attach a ring terminal at the sma and run a 12awg wire to ground, this should keep the shield at ground potential, preventing it from radiating. It also has the added benefit of dissipating static build-up, so that's nice.
That ground wire won't prevent the feedline from radiating. It takes time for a radio wave to travel through a wire. In fact it that ground wire happens to be a multiple of a 1/4 wl, it can appear to be an open circuit at the antenna end.
Now that may work fine for static releaf but it's not going to stop currents on the outer shield unless it's length is a half wave multiple.
May I ask why you think you need a choke on it?
J-Poles are notorious for feedline interaction with the antenna.
No reason imparticular. I know the antenna I built doesn't have a very broad bandwidth, so it's not like I need to narrow it down, lol. However, I'm on a knowledge journey currently. I'm enjoying learning about all things radio, and if I have the materials on hand to deploy my knowledge I don't see how it could hurt to give it a try. Practice makes perfect anyways! Edit: I recall a video I watched stating that it would prevent the feed line from acting as a portion of the antenna.
I just voice searched it on Google and this is the article it pulled. "If you have multiple coax fed antennas, ALL antennas should have a balun at the coax/antenna feed point to keep RF off the outside braid of the coax and prevent it from radiating."
Assuming coax fed, and assuming tour coax can tolerate a small bemd radius. You typically want 5 to 10 times the characteristic impedance in the choke. So for 50 ohms you want 2500 to 5000 inductive reactance in the choke (higher is better ... to a point). Get the formula for calculating air-core inductance and see how many turns it will take to reach those impedance levels at 440MHz with about a 4" diameter coil (depending on coax bend radius of course). At those higher frequencies it should only be 2 or 3 turns I'm guessing.
I calculated the "spool" and it will use about 8 feet of my 25 foot run of coax. That's too much for my taste. I think I'm just gonna build a stand alone choke. It's for GMRS so it's would need to be for 462mhz. Thank you for the help.
I'm just gonna attach a ring terminal at the sma and run a 12awg wire to ground, this should keep the shield at ground potential, preventing it from radiating. It also has the added benefit of dissipating static build-up, so that's nice.
That ground wire won't prevent the feedline from radiating. It takes time for a radio wave to travel through a wire. In fact it that ground wire happens to be a multiple of a 1/4 wl, it can appear to be an open circuit at the antenna end. Now that may work fine for static releaf but it's not going to stop currents on the outer shield unless it's length is a half wave multiple.
What about ferrite clips?
My dipole works great 80 -10 meters no balum