What is Super J pole antenna?
The Super J Pole antenna is a co-linear vertical consisting of a number of half wave length vertical elements separated with half-wave length stubs (Tuning stub) feed with a folded matching stub. The sub doesn’t receive or radiate any energy; it is simply a way of picking off the desired feed impedance.
What is the gain of a J pole antenna?
Primarily a dipole, the J-pole antenna exhibits a mostly omnidirectional pattern in the horizontal (H) plane with an average free-space gain near 2.2 dBi (0.1 dBd).
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 antenna gain increase power?
Since an antenna does not make power, increasing gain in one direction will decrease propagation in another. Typically, antennas with gain will lose the vertical propagation or “roundness” of the pattern and become flattened and elongated with the higher gain antenna you choose.
How do you ground a J pole?
The best way to ground a j-pole is, if it is on a metal mast, simply ground the mast and insure that there is good continuity from the antenna to the groundpoint. If it is on an insulated mast, ground the j-pole below the “J”, in other words, below the active segments of the antenna.
What is a ladder line?
Ladder line or “window line” is a variation of twin lead which is constructed similarly, except that the polyethylene webbing between the wires which holds them apart has rectangular openings (“windows”) cut in it. The most common type is 450 ohm ladder line, which has a conductor spacing of about an inch.
How much gain does the Super J pole have?
Some web sites suggest the Super-J has a full 3 dB gain over the plain J-Pole which is a pretentious claim obvious to anyone with a copy of the ARRL Antenna Book and other references [1]. Indeed, the Super-J will never approach the gain advantage of a properly separated two element collinear antenna, but we can get closer to this goal.
Where was the Super J pole antenna built?
The Super J-Pole antenna for 430 – 450MHz was constructed and used for FM simplex and repeater operation at my previous residence in Melbourne, Victoria from 2002 – 2007
How does a 5 / 4 wave J-pole work?
Without the stub you have a version of the erroneous 5/4 Wave J-Pole with its almost perfect cancellation of energy towards the horizon. To make the Super-J work, the conducting portion of the antenna (above the J-Feed) is made 3/2 waves long where the middle 1/2 wave is shaped to reduce it’s far-field net radiation.
Which is better Collinear J pole or Super J pole?
The collinear J-Pole, often known as the Super-J, does improve the behavior over a regular J-Pole. As many attest, there is an advantage when vertically combining 1/2 radiating sections to have a bit of separation between the half-wave end points.