Antenna analyzers, where and why?

[Tokin]

So i bought an analyzer and im wondering where i should be taking my readings from. Do i check at the radio or at the antenna or both ? Does a jumper or barrel connector have an effect i need to account for if im reading directly from the antenna?
Its real easy for me to put my antenna on a 6' pipe to tune it which is what i was planing to do tomorrow.
This is what i got at the radio.

 

[Tallman]

The first connector from antenna. You can learn much from the analyzers.

 

[Tokin]

The first connector from antenna. You can learn much from the analyzers.

Thank you. Yes thats my plan lol.

 

[Tallman]

Don't get me wrong, SWR meters are valuable. But for tuning the antenna the first connector from the antenna. Read your manuals thoroughly and learn all of the jargon.
Also, low swr does not mean resonance of the antenna.

 

[Marconi]

So i bought an analyzer and im wondering where i should be taking my readings from. Do i check at the radio or at the antenna or both ? Does a jumper or barrel connector have an effect i need to account for if im reading directly from the antenna?

Tokin, get yourself a decent 50 ohm dummy load (DL) that hopefully shows you near perfect matching values for R, X, SWR...with your DL connected directly to the analyzer, using a good barrel connector.

Also try doing the same exercises using some short coax jumpers with barrel connectors and/or male connectors as necessary.

You will find that the closer you are to the antenna feed point connection the better in real practice, but that is seldom possible.

It just takes practice. There may be some exercises in the back of your analyzer manual that will help one get more familiar with the analyzer features.

 

[Tokin]

I'm working on the jargon now lol. Running what am atm, the antenna set up is acceptable but needs to be much better before i upgrade so i splurged on a rig expert 35 zoom so i can get everything right the first time

 

[Tokin]

Tokin, get yourself a decent 50 ohm dummy load (DL) that hopefully shows you near perfect matching values for R, X, SWR...with your DL connected directly to the analyzer, using a good barrel connector.

Also try doing the some exercises using some short coax jumpers with barrel connectors and/or male connectors as necessary.

You will find that the closer you are to the antenna feed point connection the better in real practice, but that is seldom possible.

It just takes practice. There may be some exercises in the back of your analyzer manual that will help get familiar with the features.

I do have a decent dummy load or two and some 3" jumpers i made last week along with a good barrel connector.

 

[Tokin]

This is the dummy load. Not bad.

 

[binrat]

Great analyzer. Very useful for many things once you master it.

 

[Marconi]

Try adding a jumper.

 

[kopcicle]

So, analyzer for dummies (me) 101, the readers digest short version.

I have a nano vna. when I calibrate it asks for an open , a short, and a 50 ohm load. Done.
So to make this easy I attached the open, short, and dummy load to the end of the antenna that would normally attach to the antenna feed point.
In my case that is 150' away from the coax input.
Then I connect the coax to the antenna and take my readings. This virtually eliminates the coax from the equation.
Then later I look at it as a system after calibrating the vna locally and the the only thing that seems to change is the return loss. Well duh ...

Yes I do know it's other uses and could go on for several paragraphs but it's beer thirty out here on the west coast.

 

[Tokin]

With 3' jumper

 

[Jay Mojave]

Hello All: One of the neat O keen O things if the analyzer sweeps a frequency band it will show the lowest VSWR frequency allowing one to adjust O matic to were you want it. Really neat for first time designed now up in the air antennas.

Measuring the VSWR at the Antenna and then comparing it to the end of the coax will show a lower VSWR at the coax end, and a broader Bandwidth. This is because the coax has some loss and this is how it is on all antennas and coaxes.

Measuring the VSWR at the end of the coax is a valid measurement as this is what the transmitter see's.

Jay in the Great Mojave Desert.... "Next Gas 150 Miles"

 

[groundwire]

If you want a true representation of what the antenna is doing, you need to take your readings at the antenna feedpoint without any transmission line. Coax and its length does matter and will change the results. Or you can adjust the antenna with the transmission line connected and take the readings that include the influence of the coax, Its up to you. Im pretty sure the aa35 model has a setting that will eliminate the transmission line out of the equation when you take your readings. Check the manual and online. Bottom line is the true and correct way to tune an antenna is to adjust it to resonance at the operating frequency, note the resistance, connect your transmission line and compensate for any impedance mismatch between the antenna and coax with an impedance matching network.

 

[groundwire]

Measuring the VSWR at the Antenna and then comparing it to the end of the coax will show a lower VSWR at the coax end, and a broader Bandwidth. This is because the coax has some loss and this is how it is on all antennas"

Not always the case. An electrical 1/4 wavelength of coax acts as an impedance transformer. Connect a 1/4 wave stub to your perfect 50 ohm antenna and take a reading. Now you have a 2:1 swr. Huh? Impedance transformer, it can be used to your advantage if need be. Coax length DOES matter