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What is AJ pole antenna used for?
The J-pole antenna, more properly known as the J antenna, is a vertical omnidirectional transmitting antenna used in the shortwave frequency bands. It was invented by Hans Beggerow in 1909 for use in Zeppelin airships.
Do you need to ground J-pole antenna?
J-Pole antennas are half wave antennas by design. But instead of an RF ground, the antenna should have an electrical ground to protect it in case of a lightning strike. An electrical ground doesn’t enhance the RF radiation of the antenna, but it is an important safety feature on any installation.
Is AJ pole antenna balanced or unbalanced?
The J-pole is a balanced feed and the choke is required to keep RF off of the coax shield.
Does a VHF antenna need to be vertical?
Your VHF antenna attached to the AIS device needs to be as high as possible and as far away as possible from other vertical metal objects.
Can A J pole antenna be used in commercial use?
While not found often in commercial environments, the J-Pole still has a place. Collinear Super-Js work pretty well and are cheap to build. The J-Pole’s adjustable feed-point makes it easy to match choked or baluned feed-line to the antenna… assuming the J-Pole resonates correctly of course.
Can A J pole be mounted on a conductive mast?
“Mounting a J-pole directly to a conductive mast and feeding the antenna with coax without some method of preventing or reducing common mode current on the transmission line will result in producing a high proportion of the signal being wasted at high take-off angles.
Why does the bottom of the J pole not conduct RF?
The alert from the NEC crowd (since at least 1998 [5]) is how the J-Pole antenna behaves when the bottom of the J has a direct connection to other conductive structures. Many novice antenna enthusiasts, like the poster above, assume the bottom of the J in the J-Pole is at such potential to not conduct RF to anywhere, except the upper radiator.
How big is the J pipe antenna mount?
The inner diameter of the J Pipe Antenna Mount at the end for the antenna placement is 1 1/2 inches, sharp. (1 inch and 1/2) How long isvthe pipe from the base to where the pipe makes the bend?