BASIC DEFINITIONS

Brief definitions of important terminology for this Matching Balanced-Line Fed Antennas:

What is a "Balanced-Antenna"

Actually, this is a trick question.

A "Balanced-Antenna" is not just an antenna whose two halves are physical identical.  This is no assurance that the antenna is electrically balanced.

More important is that the two halves are balanced in impedance to the ground below it.

THIS is very rare here on Mother Earth, unless the antenna is over Salt Water.

In Urban Areas, where houses are very close together, having a truly balanced antenna is next to impossible.  There are simply too many objects around creating reflections of RF.

In addition to objects in close proximity to the antenna, height above ground and consistency of the ground below the antenna influence the balance.

In practice, the best we can do is understand what physically balanced and physically unbalanced antennas are.  Here are some examples:

The correct name is "Balanced Transmission Line".

It consists of two identical wires with spacing provided in various forms (as seen on the right).

People often confuse the names, but as you see, there are distinct differences Ladder-Line, Window-Line, and Twin-Line.

Although Window-Line is generally considered to be 450 Ohms, it actually comes in various impedances, depending on the thickness of the wire.
See: https://www.dj0ip.de/open-wire-fed-ant/openwire-info/

Each type has advantages and disadvantages.