开云体育

In this kind of open hardware environment it seems like it falls to the customer to do the quality control. So what should a novice VNA user like myself look at in my new nanoVNA? I don't have access to a professional VNA to compare measurements. It sounds like just checking for a RF shield may not be the key. Is there a recommendation for an acceptance test?
Joe - AF5MH

I bought these boxes to put my EasyDigi boards in. My NanoVNA came in today and fits perfectly in one of those boxes.

Please, tis is handled earlier in:
NanoVNA does not want to start -solved
You are right, the PDF is from the IP5306, but the pin 5 commands work the same. I post it anyway. It is a good alternative. I no longer need the on/off switch.
cheers, Herman ON1BES
By Herman De Dauw · #977 · Aug 13

Just to confuse matters, I decided to take that same Kenwood antenna and using some metal clamp on a large, random ground plane, I got very different results, where the return loss was larger (-23.734 dB) at a higher frequency (171.704 Mhz) and reached a lower SWR (1.139).

On Wed, Sep 11, 2019 at 11:10 AM, <erik@...> wrote:

Did you install the modified firmware?

Erik,

Are you implying that a regular NanoVNA with latest Hugen firmware will not work with this TAPR software?

if so, I'm sorry to hear it. If it would work with Hugen's firmware, even using 101 points, it could still be useful.

Also would be nice to allow using the NanoVNA's internal calibrations, CAL0 ... Cal4. That way, calibrations you made in the field (without PC) could be saved and used on the bench-top.

I understand that this software has many features that depend on the new "scan" command in your firmware, but I mistakenly thought it would be compatible with the Hugens firmware. I guess its back to NanoSharp.

Life with these nanoVNAs is getting complicated. Just saw over on eeVblog that a new NanoVNA V2 is going to be introduced that will go to 2.5 GHz without using harmonics and also use higher frequency mixers. At least it makes life interesting!

Oeps, stupid me.
Something to do...
Greetz
Ton - PA0ARR

Calibrate, calibrate, do it to the music...

We used to sing that song all day in the lab!

Ok, so will the real good cal standards please stand up!

Sounds like you found an (or) THE issue.

Alan

Just for additional information, I was doing the testing in a large conference room with very little in the room other than a table with chairs and a video projector pointing at a whiteboard. It isn't quite as acurate as a laboratory that tries to eliminate all RF radiation. On one end of the table was my laptop (nearest the door). I then placed the NanoVNA the distance of the USB cable that came with it away from the laptop. The little SMA cable is only about 6-8 inches long but I took a paper cup and made a small hole, just big enough for the SMA connector to pass through. I connected one connector to S11 and the other to the antenna. By setting the cup lid down, it made the antenna stay vertical with no real ground plane, as on a handheld radio, there really isn't a ground plane. I'm not really looking for absolute perfection, but at least something where I can compare one antenna to another.

Hi Ron,

Nice results and they look reasonable.

The handheld radio with the unit near or on the body or simply placed on a isolated table would IDEALLY show no difference! Alas, that is NOT the case and handheld (whips or helical) are influenced by the human body. We, the human body are essentially a dielectric slab, somewhat lossy, we are mostly water!

You might run some cases as you bring your hand near the antenna or bend it etc... and note the significant change in SWR. Yes, at 20 dB or better your units were well designed. Yes, they tend to be narrow band. Back in a prior era, we looked at what it would take to broadband these type antenna over a 30% or larger bandwidth. Small auto tune matching networks wer invented and helped quite well.

Alan

The "rubber duckie" sort of antennas as well as other shortened antennas for hand-held radios are always difficult to measure because they are sensitive to their surroundings as well as the size of the radio that they are mounted on. The radio case and your hand serves as part of the ground plane for the antenna.
You could take the antenna apart and remove windings (one at a time) to resonate it to the frequency of your choice. Another way is to use a telescopic antenna and mark it at the frequency that you want to use.?
It's my understanding that some very broad-band antennas use a resistor to broaden the response, but at the expense of resonate SWR.

Having an antenna on your hip or near your body, and may really throw off the resonant frequency. A metal hat with an antenna on top, looks ridiculous, but works quite well.
Stuart K6YAZLos Angeles USA

Sorry guys (and any gals). I re-calibrated the NanoVNA with the calibration devices I got with my AIM 4170D and now the SWR trace looks fine. I'll have to use the 4170 on the devices that came with the NanoVNA to see what was wrong. Sorry I was so quick on the trigger to post what looked like a problem with the NanoVNA.

Wim,
Some one previously pointed out that the deepspace demo kit is not the one shown in the nanoVNA-F photos. The nanoVNA-F demo board can be bought for around $25.00 on eBay:



Cost is more than reasonable.

I am new to playing with any type of antenna analyzer/vector network
analyzer device but decided to get started learning by purchasing the
NanoVNA, as it was relatively inexpensive. The display on the device was
extremely small and my eyes are getting old, so I first wanted to workout
software that allows me to just use my laptop. I started with NanoVNASharp
and then on to Rune’s NanoVNA-Saver. I have been playing with it a while
and I think I’m starting to get the hang of it. I’ve set the sweep count to
100, which I believe gives higher quality readings than a single sweep. I
calibrated using the short SMA cable that came with the device, along with
the double-female connector to calibrate out the short coax. Now, I wanted
to evaluate the antennas that came stock on some of my portable antennas. I
have a Kenwood TK-2180 VHF LMR portable, which I use primarily for the
Placer County Sheriff’s Search and Rescue. My other radio I bought because
it was cheap, a Baofeng UV-82C VHF/UHF dual-band portable.

For SAR, my primary use is on a repeater with an input frequency of 150.790
MHz and output of 155.160 MHz (the National Search and Rescue frequency). I
also work an event each summer doing armed security where we have an input
frequency of 159.885 MHz and output of 155.655 MHz. Basically, my needs
then are between 150-160 MHz. After calibrating my NanoVNA, I did my sweep
with the Kenwood antenna from 130-180 MHz. I exported the data as an S1P
file and then imported it into Zplot in Microsoft Excel. With this, I
created a graph showing SWR and Return Loss. To my understanding, the more
the return loss, the more resonant the antenna is to that frequency,
meaning that it is more efficient operating at that frequency, correct? I
also took notice of the Smith Chart. For the Kenwood antenna, it hits it’s
best at 152.022 MHz with a return loss of -10.682 dB and SWR of 1.826.


[image: KenwoodTK-2180StockAntenna.jpg]
[image: KenwoodTK-2180-Smith.jpg]

or the Baofeng, it appears that the dip is much narrower but has a much
“deeper” return loss at 148.558 MHz with -23.885 dB and SWR of 1.137.


[image: Baofeng VHF Antenna.jpg]
[image: Baofeng VHF-Smith.jpg]


I am trying to compare these antennas as best I can. It appears as if at
around 148 MHz, the Baofeng antenna is significantly better than the
Kenwood but fairly lousy at the frequencies I really need it. The Kenwood
appears to be a little wider bandwidth but not near as much return loss and
higher SWR. First off, are these findings typical and what does it say
about the antennas that came with each radio?

Sorry if you are receiving this as an email and getting multiple copies...
I tried sending it once before and tried to edit it, because it didn't
format correctly and deleted itself when attempting to edit.
_____________________________________
Ron Webb

I got my NanoVNA today, calibrated it, and displayed the SWR for my 40m half-square. Here's a comparison of the results with the known SWR using an AIM 4170D. Any ideas?

Hi Ron,
interesting data, and an interesting use case! My limited experience with
antennas for handheld radios indicate, that they do change their impedance
based on whether a person is holding the radio itself, and thus providing a
sort of counterpoise to the antenna. I don't know entirely how much, nor
how to simulate it reliably for measurements, but I look forward to
learning about it :-)

--
Rune / 5Q5R

The RF demo kit can also bought via Ali-express or Ebay:

,searchweb201602_10,searchweb201603_52



Still seems quite expensive for what it is, but for teaching it does seem ideal

qrp.ddc,
I ran Salil's latest script on the s1p file you attached and it runs O.K.

The only change I made to his script was substituting your filename as follows : cable = rf.Network('rg316-rg6u-rg58-50R.s1p').

The output of running the script is attached.

Did you install the modified firmware?

From: qrp.ddc@...

I also have similar bridge from aliexpress (blue board), it needs to install two jumpers near resistors in order to work. It has directivity about 40 dB at HF, about 35 dB at 100 MHz and about 25 dB at 900 MHz.
=======================

Do you have a pointer to that information, please? I have an "RF Bridge 1-3000 MHz" which seems to be very poor, and perhaps has the same issue?



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

Thank you. I have been having problems with my MW&RF account login (I'm waiting for a response from them) and have been unable to get a PDF until now.

DaveD