"Matchbox" or "Antenna Tuner" ?
WARNING: THIS PAGE IS OPINIONATED !
- Antenna Tuner?
- Antenna Coupler?
- Antenna Matchbox?
- Antenna Matching Network?
- or simply ATU?
- Remote Matchbox/Tuner ?
EFFECTIVELY THESE ARE ALL THE SAME.
They are the names we call the device which enables a transmitter with a specific impedance (usually 50 Ohms) to efficiently transfer its power into a transmission line and antenna which have a different impedance.
NOTE 1: [very important!] Just because the matchbox is able to matcht the antenna and transmission line to the transmitter with a perfect match (SWR = 1.0:1), that does not necessarily mean that all of the power being passed through the matchbox to the antenna.
THERE IS ALWAYS SOME POWER LOSS WHEN USING A MATCHBOX.
THIS IS VERY IMPORTANT TO UNDERSTAND.
NOTE 2: [and also very important!] Just because power is efficiently transferred into the transmission line (with very little loss inside the matchbox), do NOT assume the it effeciently arrives at the antenna! Don't make that mistake! Transmission lines, ESPECIALLY COAX, can add significant loss to the antenna system.
Why DJ0IP prefers the term "Antenna Matchbox" or simply "Matchbox"?
The matchbox's job is to match two devices with different impedances to each other. In doing so, we usually are able to transfer more power to the antenna system. The word "matchbox" is descriptive of it's role in the process of delivering power to the antenna.
IT DOES NOT 'TUNE' THE ANTENNA! NEVER!
(with one exception)
To do that, the matchbox would have to be located at and be a physical part of the antenna.
AND IF IT WERE PART OF THE ANTENNA, IT WOULD NOT NEED A SEPARATE NAME AND DESCRIPTION!
But it does match the antenna and its transmission line (the antenna system) to the transmitter.
Therefore I prefer to say "match" and not "tune".
POSSIBLE EXCEPTION: If you are using a Longwire Antenna, where the wire itself begins inside the shack, at the matchbox, then perhaps it can be considered as tuning the antenna (the military calls these Antenna Tuning Units) but in fact it is not changing the electrical/physical characteristics of the antenna. It is just still just matching it to the transimtter.
Most people seem to prefer to call a matchbox an Antenna Tuner.
I can't change that and I won't even try.
Just assume that Antenna Tuner means the same thing as Antenna Matchbox.
SOME SAY "IT TUNES THE ANTENNA SYSTEM"
This is more of a semantics question.
Is the matchbox itself part of the antenna system, part of the transmitter, or an independent device on its own?
In my opinion a MATCHBOX is an independent device on its own, whose purpose is to be inserted between two devices (the transmitter and the antenna system) and match them together, with the intent of increasing the amount of power that is transferred to the antenna. Unfortunately it doesn't always increase the power transferred to the antenna. Quite often it decreases the power transferred!
THE MATCHBOX IS AN ENABLER
In the presence of a mismatch, it enables the transmitter to deliver more power to the antenna system than it would without a matchbox. On the other hand, if the antenna is already well matched to the transmitter, the internal loss (in every matchbox) actually reduces the power transferred to the antenna.
WHAT DOES "ATU" MEAN?
Some people use this acronym for "Automatic Tuning Unit", meaning an automated device for matching the antenna. Others use the term simply to mean "Antenna Tuning Unit". No sense in taking sides in that arguement. I just accept both as being correct. AND I CALL BOTH "MATCHBOXES."
Same, same. Just another name for the same thing.
REMOTE MATCHBOX / REMOTE ANTENNA TUNER ?
A Remote Matchbox is a matchbox which is located outside in the open, and it either tunes automatically, or is tuned manually by a remote control head, located in the shack. Functionally, it is exactly the same thing as any other matchbox.
SO WHAT DO ALL OF THESE REALLY DO ?
- Simple Answer: They match two devices with different impedances to each other.
- More Technical Answer: What tuners do by Steve Hunt, G3TXQ.
REASON "NOT" TO CALL IT A MATCHBOX:
Some people believe that the word "matchbox" is proprietary and belongs to E.F. Johnson. This goes back to the 1950's to the days of the Johnson Viking Matchbox and Johnson Viking Kilowatt Matchbox.
I give credence to this arguement. Other similar devices at the time were referred to as "Matching Network" or "Z-Match" (a specific type). However I was unable to find any proof that E.F. Johnson ever actually trademarked the word "Matchbox".
I PERSONALLY REFER TO THEM AS A "MATCHBOX".
IMO, NO OTHER NAME DESCRIBES THEM BETTER.
YOU CAN CALL THEM WHATEVER YOU LIKE!