The RADIO WORKS' is Baluns

The RADIO WORKS™ introduced a full line of precision, 'Current-type©' baluns several years ago. They were instantly popular because 'Current-type,' baluns avoid the bad habits that conventional 'Voltage- type' baluns exhibit. 'Voltage-type' baluns try to produce equal and opposite voltages at the balun's balanced port regardless of the load impedance. Since low impedance antennas are current fed, a balun that produces equal and opposite currents at its output over a wide range of load impedances is desirable. There is little to be gained by forcing the voltages of the two antenna halves, whether the antenna is balanced or not, to be equal and opposite relative to the cold side of the balun input. The antenna field is proportional to the currents in the elements, not the voltages at the feed point.

Current-type baluns are not a new idea. They have been used in TV receivers for many, many years. TV tuners require a very wide bandwidth balun that will work with a severely mismatched antenna, like a TV's so-called 'rabbit ears' antenna. The Current-type balun was the best choice for that application.

Unfortunately, when baluns were first popularized for use with wire antennas, a voltage-type design was chosen. Other balun makers just followed along. It was years before the first true, Current-type baluns appeared on the market.

Of course, times change and today you can find entire books devoted to Current-type baluns. Only The Radio Works was the first to offer you a full line of Current-type baluns for every application.

Misconceptions

  1. Baluns will not improve SWR (the exception is when a balun used as part of a matching network, i.e. 4:1 baluns used in loops)
  2. They are not Lightning arresters, the winding inductance in most baluns is too low.
  3. Also, built-in Spark gaps don't work. The radio equipment is long gone before the 'gap' arcs over.
  4. Baluns do not allow multiband operation of single band, coax fed, antennas, nor do they make antennas more broadbanded.

These are all generalizations and, of course, there may be specific exceptions to any of them.

A balun really has only two jobs.

  1. Isolate transmission line
  2. Provide balanced output current

Proper Balun Design:

A properly engineered balun will include these design points:

  1. High winding inductance (reactance)
  2. Low stray capacitance
  3. Very short internal transmission lines- << 1/4 wave, the shorter the better

4. High power components- High voltage wire & insulation to withstand high power or a mismatch.

5. Large wire gauge reduces I²R losses.

6. Large cores - prevents saturation and provide the necessary high inductive reactance values on the low bands.

7. Mechanical considerations: Weather-proofing, rustproof hardware and a strong case to withstand loads.

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