Re: Antenna VNA comparison with manufacturer
The worst were car stereo amplifier output Watts. Still trying to figure out how they got 300W out of a 12W chip.... 73 -Jim NU0C On Sat, 16 Jul 2022 16:56:28 -0400 "Doug" <jdkearney@...> wrote: Or GMRS radio range!
Doug? -? VA3DKA
On 16/07/2022 16:20, W0LEV wrote:
Remember, marketing has the last word when a product is finally released
for sale. Also, manufacturing variations also play into the whole
picture. I wouldn't be too concerned with anything less than 2:1.
Suppliers can claim anything. Take a look at the gain figures quoted by
the many suppliers of CB antennas. They are outrageous and have no
connection to reality!!!
Dave - W?LEV
On Sat, Jul 16, 2022 at 8:06 PM Siegfried Jackstien <
siegfried.jackstien@...> wrote:
if in manufacturers smith is shifted in the inductive area ... how can
he claim an swr 1:1 and 50 ohms??
just thinking? (i have not seen the plots)
dg9bfc sigi
Am 16.07.2022 um 18:20 schrieb KENT BRITAIN:
Hi Doug, having done quite a few RFID antennas, that 1 to 1 is rather optimistic.
One thing to consider, do you have any other metal within a foot or so of the antenna? You can easily see a pair of pliers passing a foot or so
from the loop.
Good luck with your project, Kent WA5VJB
On Saturday, July 16, 2022, 11:00:36 AM CDT, Douglas Butler < sherpadoug@...> wrote:
I have a 125 kHz RFID antenna consisting of a coil and series tuning capacitor. The manufacturer supplied plots of the SWR and Z of the antenna
showing a nice 50 Ohm 1:1 SWR at resonance. I have tried to replicate
these plots using my newly purchased NanoVNA and I get radically different
plots showing a load closer to 25 Ohms and a 2:1 SWR. Measuring the L and
C separately gives about the same readings I get with my HP4801 vector
impedance meter at 125kHz, but it is near the upper frequency limit of the
HP4801 so results are shaky. I calibrated the NanoVNA over the same range
as shown in the manufacturer's plots. My Smith plots are centered on the
horizontal axis like I would expect them to be. The manufacturer's plots
are shifted up to the inductive half of the Smith chart. Both show a nice
resonant dip at 125 kHz.
Am I doing something wrong? Is the antenna manufacturer lying?
SherpaDoug WA1UWP
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Re: Antenna VNA comparison with manufacturer
Yes, the VNA is calibrated with short, open, and a 50 Ohm load through the cable. Though at 125kHz a 6" cable should not make much difference.
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Re: Antenna VNA comparison with manufacturer
Is the NanoVNA calibrated to the end of the coax at the antenna with an open, short, and load?
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Re: Antenna VNA comparison with manufacturer
Or GMRS radio range!
Doug? -? VA3DKA
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Show quoted text
On 16/07/2022 16:20, W0LEV wrote: Remember, marketing has the last word when a product is finally released
for sale. Also, manufacturing variations also play into the whole
picture. I wouldn't be too concerned with anything less than 2:1.
Suppliers can claim anything. Take a look at the gain figures quoted by
the many suppliers of CB antennas. They are outrageous and have no
connection to reality!!!
Dave - W?LEV
On Sat, Jul 16, 2022 at 8:06 PM Siegfried Jackstien <
siegfried.jackstien@...> wrote:
if in manufacturers smith is shifted in the inductive area ... how can
he claim an swr 1:1 and 50 ohms??
just thinking? (i have not seen the plots)
dg9bfc sigi
Am 16.07.2022 um 18:20 schrieb KENT BRITAIN:
Hi Doug, having done quite a few RFID antennas, that 1 to 1 is rather optimistic.
One thing to consider, do you have any other metal within a foot or so of the antenna? You can easily see a pair of pliers passing a foot or so
from the loop.
Good luck with your project, Kent WA5VJB
On Saturday, July 16, 2022, 11:00:36 AM CDT, Douglas Butler < sherpadoug@...> wrote:
I have a 125 kHz RFID antenna consisting of a coil and series tuning capacitor. The manufacturer supplied plots of the SWR and Z of the antenna
showing a nice 50 Ohm 1:1 SWR at resonance. I have tried to replicate
these plots using my newly purchased NanoVNA and I get radically different
plots showing a load closer to 25 Ohms and a 2:1 SWR. Measuring the L and
C separately gives about the same readings I get with my HP4801 vector
impedance meter at 125kHz, but it is near the upper frequency limit of the
HP4801 so results are shaky. I calibrated the NanoVNA over the same range
as shown in the manufacturer's plots. My Smith plots are centered on the
horizontal axis like I would expect them to be. The manufacturer's plots
are shifted up to the inductive half of the Smith chart. Both show a nice
resonant dip at 125 kHz.
Am I doing something wrong? Is the antenna manufacturer lying?
SherpaDoug WA1UWP
-- */If you forward this email, please delete the forwarding history which also includes my email address. When sending emails, please BCC so as to hide all addresses. Thanks for helping to prevent Scammers and Spammers from mining addresses and spreading viruses./ Doug Kearney * *Ottawa, ON *
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This email has been checked for viruses by Avast antivirus software.
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Re: Antenna VNA comparison with manufacturer
Remember, marketing has the last word when a product is finally released for sale. Also, manufacturing variations also play into the whole picture. I wouldn't be too concerned with anything less than 2:1. Suppliers can claim anything. Take a look at the gain figures quoted by the many suppliers of CB antennas. They are outrageous and have no connection to reality!!! Dave - W?LEV On Sat, Jul 16, 2022 at 8:06 PM Siegfried Jackstien < siegfried.jackstien@...> wrote: if in manufacturers smith is shifted in the inductive area ... how can
he claim an swr 1:1 and 50 ohms??
just thinking? (i have not seen the plots)
dg9bfc sigi
Am 16.07.2022 um 18:20 schrieb KENT BRITAIN:
Hi Doug, having done quite a few RFID antennas, that 1 to 1 is rather optimistic.
One thing to consider, do you have any other metal within a foot or so of the antenna? You can easily see a pair of pliers passing a foot or so
from the loop.
Good luck with your project, Kent WA5VJB
On Saturday, July 16, 2022, 11:00:36 AM CDT, Douglas Butler < sherpadoug@...> wrote:
I have a 125 kHz RFID antenna consisting of a coil and series tuning
capacitor. The manufacturer supplied plots of the SWR and Z of the antenna
showing a nice 50 Ohm 1:1 SWR at resonance. I have tried to replicate
these plots using my newly purchased NanoVNA and I get radically different
plots showing a load closer to 25 Ohms and a 2:1 SWR. Measuring the L and
C separately gives about the same readings I get with my HP4801 vector
impedance meter at 125kHz, but it is near the upper frequency limit of the
HP4801 so results are shaky. I calibrated the NanoVNA over the same range
as shown in the manufacturer's plots. My Smith plots are centered on the
horizontal axis like I would expect them to be. The manufacturer's plots
are shifted up to the inductive half of the Smith chart. Both show a nice
resonant dip at 125 kHz.
Am I doing something wrong? Is the antenna manufacturer lying?
SherpaDoug WA1UWP
-- *Dave - W?LEV* *Just Let Darwin Work* -- Dave - W?LEV
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Re: Antenna VNA comparison with manufacturer
if in manufacturers smith is shifted in the inductive area ... how can he claim an swr 1:1 and 50 ohms??
just thinking? (i have not seen the plots)
dg9bfc sigi
Am 16.07.2022 um 18:20 schrieb KENT BRITAIN:
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Show quoted text
Hi Doug, having done quite a few RFID antennas, that 1 to 1 is rather optimistic.
One thing to consider, do you have any other metal within a foot or so of the antenna?? ?You can easily see a pair of pliers passing a foot or so from the loop.
Good luck with your project, Kent WA5VJB
On Saturday, July 16, 2022, 11:00:36 AM CDT, Douglas Butler <sherpadoug@...> wrote:
I have a 125 kHz RFID antenna consisting of a coil and series tuning capacitor.? The manufacturer supplied plots of the SWR and Z of the antenna showing a nice 50 Ohm 1:1 SWR at resonance.? I have tried to replicate these plots using my newly purchased NanoVNA and I get radically different plots showing a load closer to 25 Ohms and a 2:1 SWR.? Measuring the L and C separately gives about the same readings I get with my HP4801 vector impedance meter at 125kHz, but it is near the upper frequency limit of the HP4801 so results are shaky.? I calibrated the NanoVNA over the same range as shown in the manufacturer's plots.? My Smith plots are centered on the horizontal axis like I would expect them to be.? The manufacturer's plots are shifted up to the inductive half of the Smith chart.? Both show a nice resonant dip at 125 kHz.
Am I doing something wrong?? Is the antenna manufacturer lying?
SherpaDoug WA1UWP
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There aren't many ships (real ships that don't run on underwater wings like the new Independence) that can outrun a torpedo. Even an aircraft-carrier running at 46 knots is NO match for our modern torpedo's.
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On 7/16/2022 3:04 PM, Douglas Butler wrote: 12 pound per square foot plate is thicker than 10 pound per square foot. They always go thicker, but the point is they often go different than the designer's plan. If you design a ship to go 24 knots at a certain power level and they build it with thicker plate, it won't make 24 knots. If that means it can't outrun a torpedo then thicker is not always safer.
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12 pound per square foot plate is thicker than 10 pound per square foot. They always go thicker, but the point is they often go different than the designer's plan. If you design a ship to go 24 knots at a certain power level and they build it with thicker plate, it won't make 24 knots. If that means it can't outrun a torpedo then thicker is not always safer.
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Oh, never compromise when safety is an issue or anything else for that matter. I'm assuming #12 plate was thinner, not a good choice. My 2 cents worth.
Mike C.
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On 7/15/2022 9:49 AM, Douglas Butler wrote: Theory is always incomplete. It is said that the field of thermodynamics learned much more from the operations of steam locomotives than steam locomotives learned from thermodynamics. Often electrical building codes lag advances in electrical technology by decades. In my specialty of ship hull inspection there are always the ship design drawings and the "As Built" drawings. "We ran out of 10# plate so we used 12# plate until we could get more from the foundry."
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Re: Antenna VNA comparison with manufacturer
On 7/16/22 10:32 AM, Douglas Butler wrote: I have 4" x 10" sheets of brass and aluminum I can hold up to the antenna and see the VNA plots move a bit, and steel moves them a bit more, but nothing on the scale of the difference between my plots and the manufacturer's plots.
Then I'd go for "what's the mfr's test fixture/reference design look like" (if there is one..)
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Re: Antenna VNA comparison with manufacturer
In my case, this will be a transmitter with the antenna driven by a MOSFET H-bridge with less than 1 Ohm source impedance and only a few inches of wire, so a low antenna impedance means more power can go into the antenna. But I am still getting used to using my NanoVNA and want to make sure I am not doing something stupid.
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Re: Antenna VNA comparison with manufacturer
I have 4" x 10" sheets of brass and aluminum I can hold up to the antenna and see the VNA plots move a bit, and steel moves them a bit more, but nothing on the scale of the difference between my plots and the manufacturer's plots.
Doug
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Re: Antenna VNA comparison with manufacturer
On 7/16/22 9:20 AM, KENT BRITAIN wrote: Hi Doug, having done quite a few RFID antennas, that 1 to 1 is rather optimistic.
One thing to consider, do you have any other metal within a foot or so of the antenna?? ?You can easily see a pair of pliers passing a foot or so from the loop.
Good luck with your project, Kent WA5VJB
Indeed.. at 125 kHz and low power for embedded systems, 50 ohms matched circuits would be pretty unusual. Consider the AM radio in a car - not 50 ohms. At low frequencies (consider 60 kHz WWVB receivers or 100kHz LORAN) receivers are usually just a high input Z, and the antenna resonance is used for front end selectivity. Environmental noise is huge, so it's not like you're trying to match for optimum NF. And for transmitting, unmatched systems are also common - It's not like you're running a feedline 100s of feet - a lot of transmitters in this band are basically a switch to the supply rail that turns on and off, so effectively a zero ohm source impedance. You don't care about the match - if the goal is to radiate a milliwatt or two, Thevenin maximum power transfer theorem isn't super important. "Badge reader" and RFID systems at low frequencies (and even the 13.56 MHz flavor) are interesting - the two antennas are within each other's (very) near field. It's often better to look at it as a poorly coupled transformer (since the magnetic field is often what's being used), if you want to try and model it.
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Re: Antenna VNA comparison with manufacturer
Does the mfr provide a "how we measure it" document?
Test fixturing, sample circuits, etc. are important.
You'll see this kind of thing with devices designed for use in embedded systems - For instance, there are a lot of "monolithic WiFi" antennas, which are designed for 2.45 GHz, but only on a specific board layout in a specific environment. It's a tiny SMT "chip" with no connector, and if you put it into a SMT clip fixture, it probably doesn't read 50 ohm resonance.
If your measurements are showing more inductive, it might be that the mfr is assuming some capacitance to surroundings in the circuit. I notice in the picture that there's a bunch of capacitors and spots for capactiors. It might be that the mfr intends for you to add components for a specific application.
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Re: Antenna VNA comparison with manufacturer
Hi Doug, having done quite a few RFID antennas, that 1 to 1 is rather optimistic.
One thing to consider, do you have any other metal within a foot or so of the antenna?? ?You can easily see a pair of pliers passing a foot or so from the loop.
Good luck with your project, Kent WA5VJB
toggle quoted message
Show quoted text
On Saturday, July 16, 2022, 11:00:36 AM CDT, Douglas Butler <sherpadoug@...> wrote:
I have a 125 kHz RFID antenna consisting of a coil and series tuning capacitor.? The manufacturer supplied plots of the SWR and Z of the antenna showing a nice 50 Ohm 1:1 SWR at resonance.? I have tried to replicate these plots using my newly purchased NanoVNA and I get radically different plots showing a load closer to 25 Ohms and a 2:1 SWR.? Measuring the L and C separately gives about the same readings I get with my HP4801 vector impedance meter at 125kHz, but it is near the upper frequency limit of the HP4801 so results are shaky.? I calibrated the NanoVNA over the same range as shown in the manufacturer's plots.? My Smith plots are centered on the horizontal axis like I would expect them to be.? The manufacturer's plots are shifted up to the inductive half of the Smith chart.? Both show a nice resonant dip at 125 kHz.
Am I doing something wrong?? Is the antenna manufacturer lying?
SherpaDoug WA1UWP
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Antenna VNA comparison with manufacturer
I have a 125 kHz RFID antenna consisting of a coil and series tuning capacitor. The manufacturer supplied plots of the SWR and Z of the antenna showing a nice 50 Ohm 1:1 SWR at resonance. I have tried to replicate these plots using my newly purchased NanoVNA and I get radically different plots showing a load closer to 25 Ohms and a 2:1 SWR. Measuring the L and C separately gives about the same readings I get with my HP4801 vector impedance meter at 125kHz, but it is near the upper frequency limit of the HP4801 so results are shaky. I calibrated the NanoVNA over the same range as shown in the manufacturer's plots. My Smith plots are centered on the horizontal axis like I would expect them to be. The manufacturer's plots are shifted up to the inductive half of the Smith chart. Both show a nice resonant dip at 125 kHz.
Am I doing something wrong? Is the antenna manufacturer lying?
SherpaDoug WA1UWP
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Re: Should I upgrade firmware, and if so which version to use?
Hey Dave,
I agree with you, my TI99/4A is still my favorite. (just kidding but I did use it for years) I now use win 7 and buy malware to keep it clean.
Mike C.
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On 7/13/2022 5:20 AM, David Wilcox K8WPE via groups.io wrote: Somehow you all missed my point a few days ago¡.. much of the upgrades in firmware are beyond the pay grade of many of the initial users. Until one gets used to using the nano (or your handheld or any new radio tool you have) and performing the tasks it was originally designed for WHY have new features that one doesn¡¯t need <snip>
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Re: Correction of error introduce by a transmission line connect to the VNA port 1
On Fri, Jul 15, 2022 at 11:44 AM, Diane BONKOUNGOU wrote:
Hello,
Thanks for your response I've got -462ps for the delay correction is it
good?
Best regards.
Your display looks OK but 462 ps would be the value for a very short transmission line - about 4.5 cm long. What is the length of your transmission line and what kind of coax is it? Here is a video you might find interesting. It shows how to measure an antenna located inside a product... Roger
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Re: Correction of error introduce by a transmission line connect to the VNA port 1
I would solder the coax shield to the area labeled GND in the antenna design, not to the ground plane nearby.
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Jim Shorney
Douglas Butler
Mike C.
Roger Need