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340 MHz Dipole - Calibration at Transmitter and Antenna Ends of Transmission Line

 

I recently built a 340 MHz dipole for test purposes. My NanoVNA-H4 was calibrated initially at the transmitter end of the coax cable. The first attachment shows the response of the antenna with transmission line from 200 MHz through 500 MHz. It was quite surprising to see the result. The transmission line is 15 feet of RG-58A/U coax.

The next step was to calibrate the NanoVNA-H4 at the antenna end of the transmission line. As you can see in the second attachment, the difference is quite dramatic.

I'd be interested in any comments. There is a 24 MHz difference between the various peaks and valleys in the first chart. It turns out that the transmission line is a half wavelength at 24 MHz after accounting for the velocity factor. It appears that frequencies that are multiples of 24 MHz come into play. I wonder if there is also an effect from frequencies that are odd multiples of a quarter wavelength.

73, Kent
AA6P

340 MHz Dipole 1.png
340 MHz Dipole 2.png

nanovna-H win7 windows does not seem to allow install of ST v1.5.0 driver

 

Hello,

I have searched the site and did not find a relevant message for my question.

I did connect the nanovna usb cable to the Win7 laptop before installing the new driver - which may have been a mistake. Windows did install a driver. Device Manager identified the driver as STMicroelectronics, 24/04/2010, driver version 1.3.1.0.

I downloaded and installed the STM version 1.5.0 driver installation software. Windows said the installation was successful. Device manager still showed driver as the 1.3.1.0 2010 version. Restart had no effect.

Nanovna-saver installed and works fine.
DeFuseDemo installed, recognized the Nanovna in DFU mode (even though it does not show up in Device Manager when in DFU mode), and upgraded firmware to 1.0.64.
So, as far as I can tell from the above, the device is connecting to the Win7 laptop well.

Nevertheless, when I followed all of the various driver upgrade methods shown in the Absolute Beginner Guide, plus uninstalling the driver for the device in Device Manager, re-running the STM driver installation program, directing Windows to the new DeFuseDemo driver files, nothing worked. In every case Windows said that the driver was "up to date".

So, finally, my question: is there any reason to persist with trying to get a newer version of the driver to be associated with the nanovna given that the Windows software seems to work OK with the old version? If so, how to do it?

Thank you.

Roger
Re: Call for discussion on Bluetooth HC-05 module #bluetooth

William Smith
 

Anne,

You sent us a pointer to the local copy of your manual for some device, can you either send a pointer to where you got it online, or send the actual PDF file, assuming it's not too big?

73, Willie N1JBJ

On Jul 20, 2021, at 4:19 PM, Anne Ranch <anneranch2442@...> wrote:

"interesting " tidbit -for more technically oriented NITPICKERS. .
HC_05 / 06 is JUST the module name - the ACTUAL hardware is something else.

file:///tmp/mozilla_qe0/EGBT-045MS%20&%20EGBT-046S%20Hardware%20Manual%20&%20AT%20Commands%20Reference%20Manual%20Rev.%201r0.pdf
Re: Negative Antenna Gain

 

I HIGHLY recommend that you do NOT put the amp at the rec port!
All the ambient noise will be amplified as well.? ?Dynamic range severely limited!
Any strong signals can now have enough power to damage the Nano input port.Most amps have more than enough IP3 level to take out the Nano.We are now depending on that 10-20 dB of coax loss to protect the Nano..
The best place to have the amp would be at the source antenna, but you don't lose?much if it is closer to the Nano.? ? ? ?Kent WA5VJB
PS? It is nice to see a discussion on the use of that little VNA.??? ? ? ?Seems most of the traffic is about changing the operating system.? i.e. software

On Tuesday, July 20, 2021, 12:15:17 PM CDT, Donald S Brant Jr <dsbrantjr@...> wrote:

Kent:? Since you are making up for system losses, you could place the amplifier at the receive port as well, or anywhere in the system that it is convenient.? As long as you calibrate with the reference antennas (and the amplifier or receiver is not being saturated) the results will be the same.? It would increase the susceptibility to interference, though; bandpass filtering would be helpful in this case.
Re: Issue with FW NanoVNA-H.v1.0.64

 

It still froze with the bezel removed. I will try some older firmware.
Re: Issue with FW NanoVNA-H.v1.0.64

 

DiSlord,

I'll check that. Good opportunity to remove the protective film from the display.
Re: Issue with FW NanoVNA-H.v1.0.64

 

Larry, Yes I did have verify checked.
Re: Issue with FW NanoVNA-H.v1.0.64

 

Jack, when you flashed the unit, did you select the verify option? If not, try reflashing again with verify checked.

On Tuesday, July 20, 2021, 3:53:47 p.m. EDT, Jack Mandelman <k1vt@...> wrote:

Yes, pressing the center of the lever causes it to freeze.? Moving the lever from side to side also causes a freeze.? The original FW (ver 0.2.3-2-g8ac9166 18 Oct 2019) didn't have this problem.? Could it be that the hardware of my vna is incompatible with the firmware?? Maybe I should install earlier versions.

But, the vna is still usable with a stylus or via nanovna saver.? Any additional ideas?

Thanks.

Jack K1VT
Re: Call for discussion on Bluetooth HC-05 module #bluetooth

Anne Ranch
 

"interesting " tidbit -for more technically oriented NITPICKERS. .
HC_05 / 06 is JUST the module name - the ACTUAL hardware is something else.

file:///tmp/mozilla_qe0/EGBT-045MS%20&%20EGBT-046S%20Hardware%20Manual%20&%20AT%20Commands%20Reference%20Manual%20Rev.%201r0.pdf
Re: Negative Antenna Gain

 

Yet another nitpick: Gain includes losses in the AUT. Directivity does
not include losses. Of course, the methods described here include the
losses, so the term "gain" is properly applied.

Dave - W?LEV

On Tue, Jul 20, 2021 at 11:04 AM <roncraig1@...> wrote:

Passive antennas have directivity not really gain but the term 'gain' is
often used to express the amount of energy directed in a given direction
compared to some reference antenna like a dipole.. An antenna is an energy
directing impedance transformer from transmission line to free space.

The primary issue with direct antenna measurements is environmental
effects, most significantly the effects of being close to a ground. The
environment can reflect and/or dissiplate radiated energy. The
conductivity of ground determines this.

If you are trying to measure a 40 meter antenna close to ground the
proximity of ground has a significant effect on antenna pattern and antenna
terminal impedance.
At 21-10 meter beam on a tall tower, there are less ground effects,
although there is some effect due to close proximity of metal support tower.

Ground proximity usually effects the upward warping of the antenna's main
radiating lobe. It can even cause pattern to break into multiple elevation
angle lobes at different angles of peak radiation. If you know or can
accurately predict this you can use it to optimize radiation for a given
freq/altitide ionospheric bound by adjusting height above ground of antenna.

Even with small VHF and UHF antenna you have to worry about reflections
off of ground, typically reflections from half the distance between equal
height mounted Tx and Rx points antennas. It is very easy to fabricate a
reference dipole for these frequencies and achieve a reference dipole
within a couple tenth's of dB from theoretical.

So for HF measurements, the biggest challenge is the upward pattern tilt
and possible multiple elevation lobes. You need to understand all the
peripheral environmental factors and check/eliminate their influence.
Running a long coax from Tx to Rx antenna to a nano becomes part of the
environmental impact.





--
*Dave - W?LEV*
*Just Let Darwin Work*
Re: Issue with FW NanoVNA-H.v1.0.64

 

The only way to hang the device is to press the screen with the body. Try removing the front cover.
Re: Issue with FW NanoVNA-H.v1.0.64

 

Yes, pressing the center of the lever causes it to freeze. Moving the lever from side to side also causes a freeze. The original FW (ver 0.2.3-2-g8ac9166 18 Oct 2019) didn't have this problem. Could it be that the hardware of my vna is incompatible with the firmware? Maybe I should install earlier versions.

But, the vna is still usable with a stylus or via nanovna saver. Any additional ideas?

Thanks.

Jack K1VT
Re: Issue with FW NanoVNA-H.v1.0.64

 

I didn't quite understand the essence of the problem.

If you press the center of the lever, does the device freeze?
I am unable to reproduce this problem, both of my devices are working fine.

Perhaps the contact is sticking?
Issue with FW NanoVNA-H.v1.0.64

 

I decided to do a long overdue FW update of my NanoVNA-H to the latest version 64 (previous version was 0.2.3-2-g8ac9166 (18 Oct 2019)).

After clearing config, the update went smoothly without incident. However, there is one issue that I am experiencing. The nanovna freezes anytime I press or jog the multi-function control, and requires a restart. Despite not being able to use the multi-function control, I can easily navigate the menus without incident. Also NanoVNASaver works as it should with the 64 FW.

I have read that the 53 FW version had a similar issue, but haven't noticed any discussion about this occurring with 64.

Any comments are appreciated.

Jack K1VT
Re: touch screen question - new nanovna H

 

Thank you Willie.
I followed your suggestion, removed the front cover and then the film peeled off easily using the little tab. This provided a good opportunity to tighten all the brass spacer nuts as well.
73, Roger
Re: Help with bluetooth HC-05 module #bluetooth

 

Hi Max,

That I could use the serial connection to config the usart escaped my mind indeed.

That the HC05 possibly fails is an other option.

Greetz

Jos

Op 20-7-2021 om 15:22 schreef Max via groups.io:

You do know that you issue the AT commands from the serial port, not through the Bluetooth connection. Just making sure.
Once when I had ordered 5 of these, one wouldn't work while the others had no problem. So never discount that you possibly have a bad one if you have tried everything and still can't get it to respond.
Max
On Tuesday, July 20, 2021, 07:29:13 AM CDT, Jos Stevens <jrs@...> wrote:
Since I cannot get? connect to the device I could not issue AT commands.

I did use this time to 57600 Baud to try if it worked with an other
(lower) speedrate then I used before.

When I keep a record of all things I have done, I will get out of memory ?

West6her too nice today to stay insi

Op 19-7-2021 om 22:44 schreef Gyula Molnar:
On Mon, Jul 19, 2021 at 09:38 PM, Jos Stevens wrote:

7) I did set NanoVNA-H4 to Serial speed 57600, NanoVNA-App to 57600 TeraTerm
to 57600 and COM4 and COM5 in devicemanager to 57600 Baudrate.
Why did you set it to 57600 Bd when you had to set it to 115200 in previous descriptions?
When you set BT with the AT commands, it was still 115200 Bd. This allows BT to communicate at this speed.
Make sure it's in both PC Device Manager and NanoVNA-App.
I remember you worked for it before, write it down for yourself, what do you set when it works.
--
Dit e-mailbericht is gecontroleerd op virussen met Avast antivirussoftware.
Re: Negative Antenna Gain

 

Kent: Since you are making up for system losses, you could place the amplifier at the receive port as well, or anywhere in the system that it is convenient. As long as you calibrate with the reference antennas (and the amplifier or receiver is not being saturated) the results will be the same. It would increase the susceptibility to interference, though; bandpass filtering would be helpful in this case.
Re: Negative Antenna Gain

 

Passive antennas have directivity not really gain but the term 'gain' is often used to express the amount of energy directed in a given direction compared to some reference antenna like a dipole.. An antenna is an energy directing impedance transformer from transmission line to free space.

The primary issue with direct antenna measurements is environmental effects, most significantly the effects of being close to a ground. The environment can reflect and/or dissiplate radiated energy. The conductivity of ground determines this.

If you are trying to measure a 40 meter antenna close to ground the proximity of ground has a significant effect on antenna pattern and antenna terminal impedance.
At 21-10 meter beam on a tall tower, there are less ground effects, although there is some effect due to close proximity of metal support tower.

Ground proximity usually effects the upward warping of the antenna's main radiating lobe. It can even cause pattern to break into multiple elevation angle lobes at different angles of peak radiation. If you know or can accurately predict this you can use it to optimize radiation for a given freq/altitide ionospheric bound by adjusting height above ground of antenna.

Even with small VHF and UHF antenna you have to worry about reflections off of ground, typically reflections from half the distance between equal height mounted Tx and Rx points antennas. It is very easy to fabricate a reference dipole for these frequencies and achieve a reference dipole within a couple tenth's of dB from theoretical.

So for HF measurements, the biggest challenge is the upward pattern tilt and possible multiple elevation lobes. You need to understand all the peripheral environmental factors and check/eliminate their influence. Running a long coax from Tx to Rx antenna to a nano becomes part of the environmental impact.
Re: Call for discussion on Bluetooth HC-05 module #bluetooth

William Smith
 

Now I'm confused, earier in the thread you said:

/*
My OS shows HC_05 as "paired ".
*/

Now you are saying:

/*
State "Disconnected "
*/

That one over there, the one I'm pointing at, that one should work just fine.

73, Willie N1JBJ




On Jul 20, 2021, at 12:43 PM, Anne Ranch <anneranch2442@...> wrote:

Thanks for replies, even the "funny one".
Usual response - don't quit you day job....

Now for real...

Murphy said "it works better when you plug it in " and that is MY starting point.
I usually troubleshot from START to KNOWN result and if I get no KNOWN result I just back down.
I also start with an assumption that the device will respond to START condition.
The assumption here - from other similar devices experience - the LED is an indicator , the question posted was
- what kind of indicator.

START - plug if in - power ONLY
RESULT - LED lights up
SUCCESS

Now - the above SUCCESS needs to be further analyzed .
1. Is in ONLY reacting to power ?
2. Will it supply actual state when probed by software ?

Still - no need to have anything wired BUT the power, hence NOT physically connected to other devices.

Now lets do this
Use OS to see what Bluetooth status is as far as OS goes

1. Device is identified as "HC-05" and state is "Not setup"
2. Clicking on "not set up"
Request for ID is made
3. Standard , default, HC_05 , even Chinese ID is "1234"
4. After "Confirm"
LED off for few seconds
State "Connected"
State "Disconnected "
LED flashes in about 2 seconds intervals

Any comments on that sequence?

The fast flashing has not be been reliably duplicated.



PS
Off topic
Chinese may not play fair, however, if they deliberately make junk,
as implied by comments, what makes anybody think they are that stupid and
will be able to stay in business ?
I distinctly recall drill bits , made in another county ,
which you could not drill holes in cottage cheese with ...
That country no longer makes them...
Re: Call for discussion on Bluetooth HC-05 module #bluetooth

 

Did they run out of cottage cheese?

On Tuesday, July 20, 2021, 12:43:34 p.m. EDT, Anne Ranch <anneranch2442@...> wrote:

I distinctly recall drill bits , made in another county ,
which you? could not drill holes in cottage cheese with ...
That country no longer makes them...
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