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Tim,
If you haven't used it in a while, you might want to bring it up to the latest version of firmware - use DiSlord's releases as he has made improvements and bug fixes.
You can find new firmware in the Nanovna-beta group: /g/nanovna-beta-test/message/4024

Also, did you remember to perform a calibration reset immediately prior to performing the cal so the existing cal memory is wiped?

I don't own a V2, so that's all I can help you with at this point.

Good luck.

...Larry VE3LRI

Hello Bill,

Great to see you are having fun with this. The NanoVNA is such a wonderful piece of kit.
As others have said here, you may not have to sweat this too much.
The 1/4 wave whip on most aircraft is usually 1/8" stainless steel rod and will not be as broadband as yours is now. As someone else noted, the radios are probably pretty tolerant anyway.
If you minimise the VSWR around the ATC and VFR frequencies you will actually transmit on, that will suffice. You will still receive stuff (like ATIS) at the extremities of the band OK.
Whilst the fan and bowtie suggestions for broadbanding the antenna are very valid, they do not seem to be a practical option for your vertical stabiliser looking at your photos.
As for the different lengths, that is quite feasible as other components in the aircraft, including the ply skin and the coax cable itself will affect the tuning.
You have the best tool available in the NanoVNA to do this tuning. Trust your VNA.
Most LAME electricians who install radios in aircraft would not know what a VNA was, let alone how to use it.

Just a word of warning, don't be tempted to connect the NanoVNA to the antenna cable at the airport or around other aircraft who might transmit near you.
Also, don't be tempted to use a hand held radio at home with the VNA connected.
You run the very real risk of frying the NanoVNA CH0 input if you do.

Good luck with your project. Hope you get many hours of enjoyment flying it. And many more hours of fun playing with the NanoVNA.

Cheers...Bob VK2ZRE

You can also look at ZPlots, by Dan Maguire, AC6LA, which I personally find more user-friendly, and perform the same analysis.

RigExpert’s AntScope 1, when used in consistent fashion, will provide support fir the earlier RigExpert units.

Hard to believe, but there are still a bunch of internet self-appointed experts who would rather try to cut a half-wave of coax to bring the feedpoint impedance to the shack (or the analyzer) than believe the physics. I have seen their efforts to sadly include bogus Vf use, using coax specs, rather than testing it.

Oh well.

Ed McCann
AG6CX

"Standards are /good things/...that's why there are so /many/ of them!"

John

at radio station VE7AOV

+++++

On 2022-12-07 07:52, Jim Lux wrote:

On 12/7/22 7:31 AM, Donald S Brant Jr wrote:

On Wed, Dec? 7, 2022 at 02:03 AM, Luc ON7DQ wrote:

that should of course be "at the Reflection socket" (or CH0)

I fail to understand why the designers of all of these VNAs labeled the ports CH0 and CH1, when every other VNA I have used over the past 45+ years has had Port 1 and Port 2.
This just adds to the confusion, especially when trying to explain S-parameters.? S21/S12 makes more sense when the ports are 1 and 2, much less so with 0 and 1.
73, Don N2VGU

zero based indexing.? The first person to build one happened to choose CH0 and CH1, and then it stuck.

Matlab and Fortran (and BASIC) follow the mathematician convention of 1 based.
C started zero based because of the array/pointer duality and the desire to keep the compiler simple.

Component numbering usually starts at 1, but often has a hundreds or thousands to indicate which board or assembly (that is, C302 is the second capacitor labeled on board #3)

Yeah - it's kind of like emacs vs vi; or case sensitive file and directory names.? Someone picks something, and the rest follow, or not.

--

Hey Roger, Thank-you for your reply and the transformer info. I was aiming at what I can do with AntScope using the vna, either with nano-saver or on the device itself. 73Phil, WF3W

On 12/8/22 2:16 PM, Roger Need via groups.io wrote:

On Thu, Dec 8, 2022 at 12:52 PM, Stan Dye wrote:

The normal way to do it on the nanovna is a bit different. You attach the
near end of the coax to the nanovna, then calibrate (using the
open/short/load calibration loads) at the far end of the cable. Then you
attach the antenna at the far end - all measurements then show the
performance of the antenna itself, having compensated for the coax
properties (primarily length and attenuation).

I agree with you that this "de-embedding" the cable method is the most accurate and only needs to be done once for the cable being used. Then the cal file can be saved for later recall.

This is what I do, but I don't store it in the NanoVNA. I store it in a PC program (NanoVNA-Saver) as well as a .s2p file and then use scikit-rf to do the processing.

On Thu, Dec 8, 2022 at 12:52 PM, Stan Dye wrote:

The normal way to do it on the nanovna is a bit different. You attach the
near end of the coax to the nanovna, then calibrate (using the
open/short/load calibration loads) at the far end of the cable. Then you
attach the antenna at the far end - all measurements then show the
performance of the antenna itself, having compensated for the coax
properties (primarily length and attenuation).

I agree with you that this "de-embedding" the cable method is the most accurate and only needs to be done once for the cable being used. Then the cal file can be saved for later recall.

You can alternately use the "edelay" setting on the nanovna to subtract the
length of the cable, if you look up its properties and enter the correct
value for your length of coax. This also is only approximate, and is
similar to what the RigExpert is doing.

The "edelay" method is the least accurate of all the methods because it only compensates for the propagation delay and not the attenuation. It just adjusts the angle of the "reflection coefficient" and not the magnitude which also needs adjustment.

Roger

On Thu, Dec 8, 2022 at 06:49 AM, Phil, WF3W wrote:

Hello all XMAS-gift hopefuls,

Is there a way/method/technique for subtracting coax length from readings, as
can be done in Rig-Expert's ANTScope, sftwr?

Phil,

If you like AntScope2 you can use it with your NanoVNA-H4. RigExpert added support for the -H and -H4 some time ago. Go to Settings and manually connect to the NanoVNA Com port. Some features like TDR and Calibrate are not available. You have to calibrate on the NanoVNA for the range of interest and then input the start/stop frequencies. The Cable Subtract/Add feature does work but I am not a fan of it for the reasons I posted earlier. Make sure you use metric settings as that is what is used cable length entry. Screenshot attached.

Roger

Yet another method is to measure at the shack end of the feedline. Then,
using SimSmith on your PC, propagate what you measure back to the
feedpoint. You must know the parameters of your feedline: length, Vp, and
type. For HF using anything but RG-174, the loss is pretty
insignificant.

Dave - W?LEV

On Thu, Dec 8, 2022 at 8:02 PM Roger Need via groups.io <sailtamarack=
[email protected]> wrote:

On Thu, Dec 8, 2022 at 06:49 AM, Phil, WF3W wrote:

Is there a way/method/technique for subtracting coax length from

readings, as

can be done in Rig-Expert's ANTScope, sftwr?

The AntScope2 software by RigExpert allows the user to add or subtract
cable and then make a series of measurements. There is a database of cable
types (RG-58, LMRxxx etc.) to choose from. You select the cable type and
length and it calculates the approximate impedance at the antenna when
measuring at the far cable end (subtraction method). If the measurements
were made at the antenna and you want to know what happens if you add cable
(addition method) it will calculate the approximate impedance at the cable
end. The reason I say approximate is the attenuation and velocity of
propagation are not exactly known due to manufacturing tolerances and vary
with frequency.

The equations to do the impedance transformation are well known. Attached
is an excerpt from the ARRL Radio Amateur's Handbook describing how to do
it. The equation shown will work for the "addition method". To do the
"subtraction method" you need to rearrange the terms so that ZLoad is the
desired calculation. The length of the cable, velocity of propagation,
and attenuation for the frequency being used are inputs (some unit
conversion required).

Roger

--
*Dave - W?LEV*


--
Dave - W?LEV

The normal way to do it on the nanovna is a bit different. You attach the
near end of the coax to the nanovna, then calibrate (using the
open/short/load calibration loads) at the far end of the cable. Then you
attach the antenna at the far end - all measurements then show the
performance of the antenna itself, having compensated for the coax
properties (primarily length and attenuation). This is more accurate than
the RigExpert's calculation, since as Roger noted, RigExpert uses a data
base of cable types - but any given actual cable will only be 'close' to
the data base values, whereas using the nanovna calibration measures the
actual values.

You can alternately use the "edelay" setting on the nanovna to subtract the
length of the cable, if you look up its properties and enter the correct
value for your length of coax. This also is only approximate, and is
similar to what the RigExpert is doing. You can also use the nanovna to
measure the cable's electrical length, and use that value to set the
edelay, but those are all manual steps, so calibration at the end of the
cable is usually just as easy.

Stan

Phil,
From what I've seen on the various write ups and Youtubes, you are able to determine the length, loss and any breaks in a coax by shorting the far end and using the 2nd VNA port to determine the coax properties....... from that you should be able to accomplish what you're after.
I've only had one for a few weeks and trying to get my head in gear !
JohnKK4ITX


Click Here for Zephyrhills Area Amateur Radio ClubMany of life's failures are people whodid not realize how close they were tosuccess when they gave up.?????? Thomas A. Edison

On Thu, Dec 8, 2022 at 06:49 AM, Phil, WF3W wrote:

Is there a way/method/technique for subtracting coax length from readings, as
can be done in Rig-Expert's ANTScope, sftwr?

The AntScope2 software by RigExpert allows the user to add or subtract cable and then make a series of measurements. There is a database of cable types (RG-58, LMRxxx etc.) to choose from. You select the cable type and length and it calculates the approximate impedance at the antenna when measuring at the far cable end (subtraction method). If the measurements were made at the antenna and you want to know what happens if you add cable (addition method) it will calculate the approximate impedance at the cable end. The reason I say approximate is the attenuation and velocity of propagation are not exactly known due to manufacturing tolerances and vary with frequency.

The equations to do the impedance transformation are well known. Attached is an excerpt from the ARRL Radio Amateur's Handbook describing how to do it. The equation shown will work for the "addition method". To do the "subtraction method" you need to rearrange the terms so that ZLoad is the desired calculation. The length of the cable, velocity of propagation, and attenuation for the frequency being used are inputs (some unit conversion required).

Roger

Roger,

Martin straightened me out, got it upgraded.

But, special thank for your document. Much needed.

73

Paul W1BIU

Matin,

Thank you, that's what I needed. Upgrade went like a Qiuck Brown Fox!

73

Paul W1BIU

On Wed, Dec 7, 2022 at 01:09 PM, Paul - W1BIU wrote:

What is the Latest Firmware for the NanaVNA-H4

I'm currently running:
based on DisLord @edy555 ... source
Version: 1.1.01
Build Time: Dec 30, 2021 - 00:16:53

Paul,

Hugen is the manufacturer of the NanaVNA-H4 and he tracks DiSlord's firmware release and periodically issues updates for your NanoVNA. You can get his recent update here >> . Version 1.2.14 is only slightly behind DiSlord's latest version which is currently in beta testing.

You want the -H4 SI version. The MS version is for recent hardware production where they switched to a Chinese version of the clock chip.

If you are not familiar with firmware updates you can read about it in depth in this NanoVNA User guide (pdf fromat).


Roger

On Thu, Dec 8, 2022 at 07:17 PM, Paul - W1BIU wrote:

I downloaded NanoVNA-H4.dfu ...

$ dfu-util -d 0483:df11 -a 0 -s 0x08000000:leave -D build/ch.bin

Just download the NanoVNA-H4.bin file and send it to the NanoVNA-H4 instead of the build/ch.bin file.
$ dfu-util -d 0483:df11 -a 0 -s 0x08000000:leave -D NanoVNA-H4.bin

I downloaded NanoVNA-H4.dfu to my Macbook, and have dfu-util installed and working from a Terminal screen, as I used it on my TinySA.

The only instructions I find for command line are:

$ dfu-util -d 0483:df11 -a 0 -s 0x08000000:leave -D build/ch.bin

This appears to require that I do a build first. Can I skip the build and just use the NanoVNA-H4.dfu download?

On 12/8/22 8:23 AM, William tunna wrote:

Thank you for the highly detailed response Bob, I have indeed got the shielding from the coaxial soldered to the strip on the top of the fuselage and the centre core soldered to the strip going up the fin of the aircraft. At the moment I have got 3 ferrite cylinders just off from where the coaxial connects to the antenna and I've run the whole coaxial to the cockpit the the final TNC connector, which is where I am measuring from.
Luckily my copper tape has conductive adhesive, so I reset my antenna by making both lengths the same. I have then taken 1cm off each end at a time and have found I had to take about 5cm off each end to get it within specs. I think the biggest problem with this antenna is the control rod for the tail runs all the way behind the fin. I have found though, that if the ground strip is 3cm longer than the other strip, it really improves the SWR in the lower ranges without affecting the higher frequencies. Not sure if this is a big deal or not, here is the improved SWR chart in the image
Tomorrow I'm going to try adding more copper tape either side of the existing tape to increase the width, see if this helps.
Thanks everyone else for the helpful responses

The fuselage itself (and everything else) will "load" the antenna (it's not operating in "free space" so the element will likely be shorter than the free space length.

And cut and try is how you do it. A VNA and copper foil tape is an excellent approach. Just be aware that the feedline and VNA are part of the system as well.

When I was building an antenna for an ATV link on 70cm from a model sailplane, that's exactly what I did. The first try was foil on waxed paper (part on the fuselage, part on vertical tail) (I didn't want to tear the monokote). Got it close, then stuck the foil to the plane, and trimmed and snowflaked it.

As others have noted, if you want to cover the whole band (do you really need to?) then a fan, bowtie, or multi parallel dipole works nicely. Cut one strip for the high end, one for the low end, have them about 30 degrees apart (if it fits) and then cut and try.

Doing this with an old school SWR bridge would be impractical. But a VNA - you'll see it right away.

A typical dipole made with relatively thin conductor has a 2:1 bandwidth of
roughly 10% or ±5% of the center frequency. Your total bandwidth is 136 -
117 = 19 MHz Please note this is not mHz which would be millihertz!
10% of midband is 0.10 X 126.5 = 12.7 MHz.

Bottom Line: It is highly unlikely you will be able to cover the entire
117 to 138 MHz band with acceptable SWR.

Instead of the strictly linear arrangement, I'd suggest making a fan
dipole. This configuration employs triangular elements of the same length
as your linear dipole, but flares out as it reaches the ends away from the
coax connection point. Each element of the fan dipole will form a
"shallow" isosceles triangle. The ends or base of the triangle might be
3-inches long. Experiment with this.

Dave - W?LEV

On Thu, Dec 8, 2022 at 12:33 PM Ken Goodings VE3MVN, VE0SH <
kengoodings@...> wrote:

Each half of your dipole should be around 60 cm. They should be both equal
in length for your center frequency of 126 mhz
Trim each end by the same amount on each test.
Half wave dipole length calc in inches for vhf is 5905÷ f or 5905÷126=
48.86 inches
Each half is 23.4 inches or 59.5 cm

On Thu., Dec. 8, 2022, 6:51 a.m. William tunna, <willtunna@...>
wrote:

Hi all,

I hope this is okay to post in this group as I'm new here. I've built a
dipole antenna using copper tape and a RG58 coaxial for my kit aircraft

as

per some plans I have and I wanted to test it to see if it matched with

my

radio specifications of having a VSWR of under 2.5. The frequency range

for

the air band is 117MHz to 136MHz and I am wondering how I can flatten my
SWR curve I'm seeing on the NanoVNA. As you can see from the pictures,

I'm

achieving an SWR of 1.57 at the midway frequency around 127MHz but at the
lower frequencies it goes all the way up to 4.2 SWR.

Things that I have tried -

- I've added length to the ground strip, which makes the SWR closer to 1
in the lower frequencies but increases the SWR in the higher frequencies.
- I've taken away from the antenna strip and the SWR goes down in the
higher frequencies but makes it a lot worse in the lower frequencies.

I started with a ground strip of 540mm and an antenna strip of 545mm, and
now I'm at 560mm on the ground strip and 485mm on the antenna strip.

What's the best way to go about making this better? (Also, if I've made

no

sense, it's because I have no idea what I'm really doing...)

--
*Dave - W?LEV*


--
Dave - W?LEV

Thank you for the highly detailed response Bob, I have indeed got the shielding from the coaxial soldered to the strip on the top of the fuselage and the centre core soldered to the strip going up the fin of the aircraft. At the moment I have got 3 ferrite cylinders just off from where the coaxial connects to the antenna and I've run the whole coaxial to the cockpit the the final TNC connector, which is where I am measuring from.

Luckily my copper tape has conductive adhesive, so I reset my antenna by making both lengths the same. I have then taken 1cm off each end at a time and have found I had to take about 5cm off each end to get it within specs. I think the biggest problem with this antenna is the control rod for the tail runs all the way behind the fin. I have found though, that if the ground strip is 3cm longer than the other strip, it really improves the SWR in the lower ranges without affecting the higher frequencies. Not sure if this is a big deal or not, here is the improved SWR chart in the image


Tomorrow I'm going to try adding more copper tape either side of the existing tape to increase the width, see if this helps.

Thanks everyone else for the helpful responses