Coil losses - range of loss in dB to be expected between good and bad matches

[TheBlaster]

In an ATU (AMU) we have caps and coils, same with many antennas that need a coil or an L match.

In some of the worst matches that people use an ATU for what can be the ranges of internal coil losses in dB ?

As an example of a very inefficient match I have a 160m band antenna 11m of vertical wire, it is a coil of a bout 38 turns on a 6 inch pipe. I am going to guess that the coil losses might be 12-15dB loss or possibly more. I estimate 100W in will probably produce about 5W radiated. A good coil match example can be that of a 5/8 wave or a 1/2 wave CB vertical antenna.

Does anyone have some ranges of potential coil losses in dB that could be expected matching difficult loads.

 

[TheBlaster]

I will add this as it seems potentially relevant though the " 3dB - 8dB" coil losses mentioned do not seem to have much surrounding data. (probably due to complex maths)

https://www.iw5edi.com/ham-radio/4151/calculate-your-antenna-gain

Here the suggestion is that 1Watt of 100watts will be radiated from a base loaded 160m band 10m long vertical.

I have always felt that ATU coil loss need to be deducted from any "pattern gain" to make any comparative performance sense.

 

[TheBlaster]

ATU's - often coveted, you would be forgiven for thinking they are perfect and even desirable devices given statements such as : "It'll match a bit of wet string" Losses ? Rarely ever spoken of. From what I can gleen it seems you lose around 1dB on an average expected match. Of course this is a gross over simplification which suits me, and seemingly everyone on here it seems given the lack of answers.

1dB is hard to find when it comes to single wire antenna design especially for much of HF given the sizes of an efficient antenna.

https://owenduffy.net/blog/?p=7035

https://www.ab4oj.com/atu/main.html

For multi band use of a wire I suppose it is a reasonable necessary loss. I would prefer to have 1dB gain myself. As that is a gain of 2dB over use of an ATU.

2dB is really hard to find in single bits of wire.

 

[Handy Andy]

Be sure to distinguish the differences between Effective Radiated Power versus the Loss - for in some instances (as a general guide not meant to insult anyone) a dummy load can be considered 100% Efficient - but as only SWR is to losses as Resonance is to Length.

You can't use a dummy load as efficiently as an antenna (e.g. - ERP) - as also (compared to) the analogy of the Resonant Length - when you increase the frequency used on the Resonant Length, as you get closer to multiple fractions of wavelength. The appearance of the antenna changes from one set of values - to another - which increases GAIN as a factor of dB - but not in the sense of power - but as power DIRECTED into a pattern increasing the Effective Radiate Power.

You can also increase the Resonate Length of antenna - make it LONGER into those fractional wavelengths - and obtain those same lobed patterns which help provide a form of gain, not as a power - but as a radiative pattern of change.

So, to claim matching as a loss, I don't see it that way, it only becomes a loss if the Gain in pattern (or capture if that would be the word) can't offset the coupling losses the antenna has as an impact to the system - the system being the whole mess strung up and connected to the transmitter.

You mentioned the 6-in coil pipe antenna - knowing someone who has used one - I did find it rather hilarious to use such an antenna - but in its ability to be turned and aimed - makes such a device rather useful to "cut the mustard" when it came to having local QSO's

 

[TheBlaster]

Matching is unquestionably in the category of loss, unless it is a 1/4 wave without need of a coil or an LC match. I do understand everything you have said and do not directly see pattern gain as the direct opposite of a coil or LC loss. However if you can get pattern gain, it is worth taking as gain is gain when it comes to effective DX antennas. Give me the lower angle peak gain each and every time, assuming there are no nulls above said angle.

It needs looking at holistically as a complete system. Wire length and matching devices are part of that system. They all relate to performance result. You can lose some energy as heat along the way, the less you lose the better. Using an ATU is an end user choice, as is a choice of antenna. Along with the losses an ATU causes.

It all adds up or subtracts from the overall antenna system performance.

I understand an ATU may provide great convenience, a small compromise for a lot of flexibility but they are still a lossy device in your antenna system. Each to their own choices.

 

[Handy Andy]

I wish you well in your efforts, I was just stopping in to admire your own research.

Wishing you the best!

 

[TheBlaster]

I wish you all the best too.I probably have a lot of CBer left in me. I like a basic yet thorough approach. 9 times out of 10 that works just as well as a more complicated and expensive way.

In fairness we need to deduct coil/balun winding/core losses from any other non resonant / non close to 50 Ohms match antenna. The difference is home brew can control that a by using nice thick wire.

The most important is that all of these losses are understood to be present as a system and can be deducted from your gain/loss and overall system performance. No free lunches.

You know by yourself if your system works really well or otherwise. And as a consequence where you can make improvements and that we almost all want.

 

[jacquelyn S cortes]

And the

Be sure to distinguish the differences between Effective Radiated Power versus the Loss - for in some instances (as a general guide not meant to insult anyone) a dummy load can be considered 100% Efficient - but as only SWR is to losses as Resonance is to Length.

You can't use a dummy load as efficiently as an antenna (e.g. - ERP) - as also (compared to) the analogy of the Resonant Length - when you increase the frequency used on the Resonant Length, as you get closer to multiple fractions of wavelength. The appearance of the antenna changes from one set of values - to another - which increases GAIN as a factor of dB - but not in the sense of power - but as power DIRECTED into a pattern increasing the Effective Radiate Power.

You can also increase the Resonate Length of antenna - make it LONGER into those fractional wavelengths - and obtain those same lobed patterns which help provide a form of gain, not as a power - but as a radiative pattern of change.

So, to claim matching as a loss, I don't see it that way, it only becomes a loss if the Gain in pattern (or capture if that would be the word) can't offset the coupling losses the antenna has as an impact to the system - the system being the whole mess strung up and connected to the transmitter.

You mentioned the 6-in coil pipe antenna - knowing someone who has used one - I did find it rather hilarious to use such an antenna - but in its ability to be turned and aimed - makes such a device rather useful to "cut the mustard" when it came to having local QSO's

And the link of your feed line to the antenna should be at least 100ft long 50,OMS Like Rg8u,for that low SWR,73

 

[AudioShockwav]

And the

And the link of your feed line to the antenna should be at least 100ft long 50,OMS Like Rg8u,for that low SWR,73

At least 100 feet?

The correct feedline length is what it takes to get from the station to the antenna.
If it's only 63.5 feet to the antenna, that's what you need.

73
Jeff

 

[Moleculo]

Are there losses as a result of using a tuner? Yes, but not as much inherently in the tuner as you might think. Most of the loss occur in the feedline between the tuner and the feed point of the antenna; Maxwell's Reflections discusses this in length.

If you require a tuner, which is usually the case as you move down lower in the bands, you can minimize the losses significantly if you are able to move the tuner right adjacent to the feed point of the antenna. For example, a remote ATU used in conjunction with a 160m vertical can be a quite effective arrangement. Another example is when using highly portable radios like the Elecraft KX3 or KX2: attaching a BNC pos/neg binding post adapter directly to the radio with a random length radiating wire and a ground radial with the built in ATU will perform better than a length of coax ran to some type of Unun and wire. Of course, other considerations such as mechanical connections may out weight the best antenna configuration for performance.

Another option for minimizing losses when using a tuner is to change the feedline to balanced ladder line (or similar).