开云体育

Peter:

It really, really is a fantastic book--- The KINDLE digital download
version has links, diagrams and explanatory text---
DO THIS:
1. Estimate the price of your ham shack's current equipment. ENTER THE
NUMBER HERE
2. Estimate the price of the last restaurant meal you ate. ENTER THE NUMBER
HERE

3. Divide cost #2 by cost #1 and express as a percentage. ENTER THE
PERCENTAGE HERE

4. The Kindle cost of the NanoVNA Explained downloadable digital version is
$18.99 USD as of now
5. Compare Cost #2 with Cost #4. IF #2>>#4, then getting that book is
cheaper than your last restaurant

6. Last step: Buy the book; it is "budget dust" compared to the price of
your ham gear.

On Sun, Jan 19, 2025 at 7:57?PM Peter Jones via groups.io <jonesypeter=
[email protected]> wrote:

Thanks Bill,

Maybe someone can explain it in a message?

I think our radio club may have a copy, but I'm not visiting for a few
weeks.

Thanks

Just remember that if you want to know where the antenna is resonant (reactance = 0) you have to measure at the feedpoint of the antenna NOT at the end of the transmission line in your hamshack.

It is usually not convenient to place the NanoVNA at the antenna feedpoint but you can get the same result by "de-embedding" the transmission line. This requires that you calibrate at the end of the transmission line using your SOL cal loads. If you save the results you only have to do this once.

Warning - If your coaxial cable has common mode current on the outer surface of the coax shield then this "third wire" is forming part of the antenna system and you results will not be the same as if the NanoVNA was directly connected at the antenna feedpoint. You often see common mode current when you connect an unbalanced transmission line to a dipole. This can be reduced considerably by using a current balun at the feedpoint which helps to choke the RF current.

Thanks Steve!

Thanks Bill,

Maybe someone can explain it in a message?

I think our radio club may have a copy, but I'm not visiting for a few weeks.

Thanks

Look at the display options to show R and X traces. But the easiest way to see resonance is on the default smith chart- wherever the trace crosses the horizontal axis is a resonance point. You can move your cursor there, and read the frequency and the corresponding R (X is 0). The closer R is to 50 ohms, the closer your resonance is to the minimum SWR.

Peter:

Yes. Buy a copy of "NanoVNA EXPLAINED" by Mike Richards, G4WNC. It's a
RSGB book.
Get it on Amazon. I have the Kindle version downloaded immediately after
buying it.

Very thorough and easy to follow.

And yes, you can use the various tracks to display info.

73
Bill K2TNO

On Sun, Jan 19, 2025, 2:38?PM Peter Jones via groups.io <jonesypeter=
[email protected]> wrote:

Thanks Bill,

Sorry, my image didn't appear as I had planned.

So can resistance and reactance be displayed at the same time (I assume
multiple traces?).

Can anyone direct to a tutorial?

Thanks
Peter

Thanks Bill,

Sorry, my image didn't appear as I had planned.

So can resistance and reactance be displayed at the same time (I assume multiple traces?).

Can anyone direct to a tutorial?

Thanks
Peter

Yes NanoVNA can measure resistance and reactance as well as a Smith chart.
Resonance is the frequency at which the antenna is purely resistive, and no
reactance.

You seem to be already aware that the "frequency of minimum swr" is not
necessarily the "resonant frequency." But, it can be. Read the ARRL
Handbook or ARRL Antenna Book for clarification.

Bill K2TNO

On Sun, Jan 19, 2025, 2:14?PM Peter Jones via groups.io <jonesypeter=
[email protected]> wrote:

Greetings,

I've recently completed the construction of my first 'home brew' antenna
(1/4 wave vertical). A radio friend of mine suggests I should look at
resonance as well as SWR.

SWR is fine, but I can't see anything online about an R/X chart (similar
to that available on the RigExpert).

Can I do this on the NanoVNA V4?

Thanks

Peter M0LMG

[img][/img]

Greetings,

I've recently completed the construction of my first 'home brew' antenna (1/4 wave vertical). A radio friend of mine suggests I should look at resonance as well as SWR.

SWR is fine, but I can't see anything online about an R/X chart (similar to that available on the RigExpert).

Can I do this on the NanoVNA V4?

Thanks

Peter M0LMG

[img][/img]

try cw mode

All,

The groups.io fee for maintaining this group has been paid. I received several donations after I sent the notice that the amount required had been reached and have refunded those donations. For those of you who donated after the required amount had been gathered, thank you for your donation and please feel free to donate next year. For those of you who donated and whose donations are went to the subscription fee, thank you as well.

I will be transferring the donations to my account from which the fee was debited later today.

DaveD

--
This email has been checked for viruses by Avast antivirus software.
www.avast.com

The screenshot function was finally solved, the reason was that there was a problem with my chip, I didn't find that the SD_CS pins were pulled low when I probed the waveform, which was very strange, and finally I used the diode function of the multimeter to measure the voltage drop between the SD_CS pins and GND, and confirmed that the SD_CS pins were damaged, because the normal IO and GND have a voltage drop of about 0.6V, and finally I replaced an IO, and the screenshot function was used normally

On Fri, Jan 17, 2025 at 06:40 AM, ?lvaro Felipe Hernández wrote:

Whenever I have made measurements to antennas I have had very different
results -even calibrating the antenna feed coaxial cable- than placing my
VNA-F with a 10 cm. patch cord directly to the antenna feed.

This happens when you have common mode issues and the outer surface of the coax shield has become part of the antenna. For example - A dipole connect to coax with out a balun will have this issue.

Roger

If you want a precise and real
measurement you should connect the NANO-VNA as close as possible to the antenna feed
point.

I have a -F and I have never encountered this problem with either a 10 m coaxial or a 40 m coaxial (3-30 MHz). I make my measurements from the station, the NanoVNA being connected to my PC.

The measurements I make, by calibrating at the connection to the antenna are a priori good since this is where I insert my LC adapters. These adapters are calculated on the basis of the s1P files; I measure the components. Then I refine the settings by mounting the adapter upside down in order to find the impedance measured in the s1p. And it works.

This is also the only way to integrate the coaxial sheath into the measuring device.
--
F1AMM
Fran?ois

-----Message d'origine-----

De la part de ?lvaro Felipe Hernández
Envoyé : vendredi 17 janvier 2025 15:40

Whenever I have made measurements to antennas I have had very different results -even calibrating the antenna feed coaxial cable- than placing my VNA-F with a 10 cm. patch cord directly to the antenna feed. Obviously I have had to remove the antenna feed cable and calibrate the VNA with the cable stretched on the ground. If you want a precise and real measurement you should connect the NANO-VNA as close as possible to the antenna feed point.
--
ALVARO, EA8ARX

RE: "digging in"
Old proverb:

"When you're up to your ass in alligators it's hard to remember that your
job was to drain the swamp!"


Bill K2TNO

On Thu, Jan 16, 2025 at 6:19?PM W0LEV via groups.io <davearea51a=
[email protected]> wrote:

The best way to conquer the "steep learning curve" is to just dig in.....

Dave - W?LEV

On Thu, Jan 16, 2025 at 6:17?PM Roger Need via groups.io <sailtamarack=
[email protected]> wrote:

On Thu, Jan 16, 2025 at 10:09 AM, W0LEV wrote:

SimSmith can do all this and far more..... And.....its freeware:

Yes it can do much more and it has a steep learning curve...

Roger

--

*Dave - W?LEV*


--
Dave - W?LEV

The best way to conquer the "steep learning curve" is to just dig in.....

Dave - W?LEV

On Thu, Jan 16, 2025 at 6:17?PM Roger Need via groups.io <sailtamarack=
[email protected]> wrote:

On Thu, Jan 16, 2025 at 10:09 AM, W0LEV wrote:

SimSmith can do all this and far more..... And.....its freeware:

Yes it can do much more and it has a steep learning curve...

Roger

--

*Dave - W?LEV*


--
Dave - W?LEV

On Thu, Jan 16, 2025 at 10:09 AM, W0LEV wrote:

SimSmith can do all this and far more..... And.....its freeware:

Yes it can do much more and it has a steep learning curve...

Roger

SimSmith can do all this and far more..... And.....its freeware:



And an excellent tutorial:



Dave - W?LEV


On Thu, Jan 16, 2025 at 5:32?PM Roger Need via groups.io <sailtamarack=
[email protected]> wrote:

There is an excellent free program for Windows that really helps to
understand how transmission lines work. It is called TLDetails >>


Using this program you can select from commonly available transmission
lines (RG8, RG58, twinlead etc.), set a load impedance, cable length and
frequency and then it calculates the SWR, Return Loss, impedance and plots
on a Smith Chart. Many other useful features as well. Here is an example.

--

*Dave - W?LEV*


--
Dave - W?LEV

There is an excellent free program for Windows that really helps to understand how transmission lines work. It is called TLDetails >>

Using this program you can select from commonly available transmission lines (RG8, RG58, twinlead etc.), set a load impedance, cable length and frequency and then it calculates the SWR, Return Loss, impedance and plots on a Smith Chart. Many other useful features as well. Here is an example.