¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. Nanovna-Users
  2. Topics

High impedance antenna measurments #applications

 

Anyone has used the nano with an antenna bridge ( or noise bridge ?) to measure antenna impedances other than 50 ohms, like 300 ohms and up ?
 

Are you going to use one?

Op 20-7-2022 om 06:00 schreef Observer:

Anyone has used the nano with an antenna bridge ( or noise bridge ?) to measure antenna impedances other than 50 ohms, like 300 ohms and up ?
 

yep, I am experimenting with hf antennas, with unknown, or predicted high z or very low z
 

You won't need it. The nano measures it all.

What's your name?

Op 20-7-2022 om 10:34 schreef Observer:

yep, I am experimenting with hf antennas, with unknown, or predicted high z or very low z
 

Is there a performance specification for the nanoVNA?

Particularly interested in V4.2 HW version as I have one

Kind regards

Ed G8FAX
 

In my possible dumb imagination I would use a 10 or 20 dB attenuator to avoid mismatch on the NanoVNA side. Then measure the impedance. Then I would make an a-symmetrical attenuator from 50 to that first guess en measure again. This would only require some resistors. Or am I wrong?

73 Alex. PE1EVX
 

Or less like 3 or 6 dB
 

On 20/07/2022 10:19, alex wrote:
In my possible dumb imagination I would use a 10 or 20 dB attenuator to avoid mismatch on the NanoVNA side. Then measure the impedance. Then I would make an a-symmetrical attenuator from 50 to that first guess en measure again. This would only require some resistors. Or am I wrong?

73 Alex. PE1EVX
I think that would make high/low measurements much less accurate!

To the OP: As a suggestion, anything more than, say, 5 times from the nominal
50 ohms will be subject to increasing inaccuracy. Say 10 - 250 ohms you might
be OK? Perhaps someone might like to confirm this? Perhaps better if you use
a 4:1 transformer - the appropriate way round?

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv
 

I've measured in the HF range only.

Low and high impedances, testing with resistors.

The results are in the following documents:






73,

Arie

Op 20-7-2022 om 11:24 schreef David J Taylor via groups.io:

On 20/07/2022 10:19, alex wrote:
In my possible dumb imagination I would use a 10 or 20 dB attenuator to avoid mismatch on the NanoVNA side. Then measure the impedance. Then I would make an a-symmetrical attenuator from 50 to that first guess en measure again. This would only require some resistors. Or am I wrong?

73 Alex. PE1EVX
I think that would make high/low measurements much less accurate!

To the OP: As a suggestion, anything more than, say, 5 times from the nominal
50 ohms will be subject to increasing inaccuracy.? Say 10 - 250 ohms you might
be OK?? Perhaps someone might like to confirm this?? Perhaps better if you use
a 4:1 transformer - the appropriate way round?

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv
 

On 20/07/2022 11:14, Arie Kleingeld PA3A wrote:
I've measured in the HF range only.

Low and high impedances, testing with resistors.

The results are in the following documents:






73,

Arie
Most interesting, Arie, thanks for posting.

Judging by your plots, I'd say the 1-ohm to 470-ohms range is quite acceptable.
More complex, though for someone wanting to measure antennas!

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv
 

On 7/20/22 2:13 AM, Ed G8FAX wrote:
Is there a performance specification for the nanoVNA?
Particularly interested in V4.2 HW version as I have one
Kind regards
I don't know that there's published specifications - it's more "we built it, you use it, as found" There's a fair amount of lore - measurements people have made, etc.

It's kind of different from buying a VNA from, say, Keysight where they have a published spec sheet, acceptance tests, etc. That is part of what makes the FieldFox cost 100x what the NanoVNA costs.

Practically speaking, it puts out about 0 dBm, has about 60 dB dynamic range (sometimes as much as 80 dB), covers 50 kHz up to at least 900 MHz (some versions cover more), has 101,201, or 401 points in a sweep (depend on software version).
 

On 7/19/22 9:00 PM, Observer wrote:
Anyone has used the nano with an antenna bridge ( or noise bridge ?) to measure antenna impedances other than 50 ohms, like 300 ohms and up ?
I don't think you want to use them together. The NanoVNA directly measures impedance vs frequency. Yes, the usual display is S11 referred to 50 ohms, but you can convert that to R and X (and, in fact, it will do that for you)

No reason why it won't measure 300 ohms.
 

You can easily measure impedances up to several thousand ohms using the S11 (CH0 or Port1) shunt method if you have a decent test jig (see group wiki for details). The higher you go the worse the accuracy. Here is a previous post on the sibject.
Tests of 1K and 3K resistors attached.

/g/nanovna-users/message/20941

This topic of measuring components and what test jig to use has been discussed many times in this group. This post should answer many of Observer's questions...

/g/nanovna-users/topic/pitfalls_of_measuring/80744049?p=Created%2C%2C%2C20%2C1%2C0%2C0&jump=1


Roger

Parallel Impedance - R3k.png
Parallel Impedance - R1k.png

 

The NANOVNA can be used directly at 300-ohm resistance. Careful
calibrationn and placement of the cursor is required to ultimately read
values is required, but can be accomplished without introducing another
piece of uncertainty.

Dave - W?LEV

On Wed, Jul 20, 2022 at 4:01 AM Observer <tvstreamdevice@...> wrote:

Anyone has used the nano with an antenna bridge ( or noise bridge ?) to
measure antenna impedances other than 50 ohms, like 300 ohms and up ?





--
*Dave - W?LEV*
*Just Let Darwin Work*
--
Dave - W?LEV

1 - 14 of 14