Use Of Balun In Antenna. The intent of the balun is to increase the impedance to ground seen by the outside shield current, and thus to minimize (ideally eliminate) the outer shield current. Use a heavy copper wire (not steel or aluminum) or, better yet, low inductance conductors which have anaspect ratiothat is other than round.
balun for folded dipole antenna dg7ybn.de/Symmetrising/Sym… Flickr from www.flickr.com
Even standard dxe baluns are better than many competing baluns, because many competing baluns use thin enamel for wire insulation. Special dx engineering tuner baluns for antenna tuners or systems with high swr, we have a special balun. The choke balun is a a cheap and easy method of removing common mode currents from the feedline, provided it is manufactured correctly.
Do Dipoles Need A Balun?
Baluns isolate a transmission line and provide a balanced output. The intent of the balun is to increase the impedance to ground seen by the outside shield current, and thus to minimize (ideally eliminate) the outer shield current. Prevent radiation / pickup from coax outer conductor:
Although Not Necessary, A 1:1 Isolation/Choke Balun (Models, 1110, 1113, 1115 Etc.) At The Transmitter End Of Feedline Will Stop Rf From Entering Your Equipment And Reduce Receiver Noise Caused By Common Mode Currents.
By employing a balun, you are somehow forcing the currents on each leg of the dipole to be equal, so that no current returns on the coax, so that the coax does not radiate and act as part of the antenna. This coil acts as an rf choke and prevents the common mode currents returning back down the feed line. Paul, a dipole does not *have* to have a balun.
N/ (Portmanteau Of Balanced To Unbalanced) Is An Electrical Device That Converts Between A Balanced Signal And An Unbalanced Signal.
The 4:1 baluns in most antenna tuners are voltage types because, really the only reason, they are cheaper. Related faq for does a loop antenna need a balun? #1 ~ do you use a balun with your antron, anttron, solorcon, maco or other metal or fiberglass cb/11 meter omni antenna's?
Copper Forum Member's, Here Are A 4 Good Question's For Everyone Who Use's A Metal Or Fibergless Omni 11 Meter/Cb Antenna.
Hf balun is even applied with hf monopole antennas to widen their bandwidth. When we say a balun or unun is a 4 to 1 device it will work just as well backwards. This antenna can use a coaxial cable feed and the balun is located right at the dipole element to ensure that the each side of the element receives equal currents and prevents external shield currents.
A 4:1 Impedance Transformation Has Useful Applications, As You Mentioned In An Ocf, Or Any Antenna That Is Intentionally Fed At A Higher Impedance Than The Characteristic 50 Ohms Of Coax.
There are many designs, but one of the most common and effective is a simple common mode choke, also known as a 1:1 current balun. A dipole is what is termed a balanced antenna. Where radiation pattern of the antenna is important:
