开云体育

That being said, the aim of a radio amateur is to have a QSO, without
damaging equipment and causing interference (RFI)!
All these - balun, common mode choke, SWR meter and NanoVNA, are aids to
achieve that end result.

73
Jon, VU2JO

On Tue, Apr 1, 2025 at 9:04?PM W0LEV via groups.io <davearea51a=
[email protected]> wrote:

QUOTE: However a successful QSO is not scientific evidence of a "good" or
"bad" antenna.
If it works, great. But do not use this as evidence of optimum antenna
performance:-)


**

I'd also add that a low SWR is also not an appropriate means of declaring
an antenna good.

Dave - W?LEV

On Tue, Apr 1, 2025 at 6:59?AM Bob Ecclestone VK2ZRE via groups.io
<becclest@...> wrote:

Hello Jon,

As you wish to use the antenna on the higher harmonics as well as 2M, I
would suggest you use ferrites to create a Common Mode Choke (CMC) as
noted by Roger.
I suspect (but do not know, I am no expert here) that it would be
difficult to build a broadband balun to cover your frequency range (x5,
x7) at TX power levels.

As for some of the other comments to this thread, I did not say that
your antenna would not work without a balun or CMC.
What I said was that without a balun or CMC, the connection of an
unbalanced VNA to a balanced dipole would not give correct measurement
results of the antenna because the feedline would become part of the
antenna measurement as also noted in other responses in this thread.

Your experience when you used a replacement "load" to do your
calibration just emphasises how critical it is to do calibrations
correctly and to treat your calibration SOLT "standards" with care and
respect.

We can measure antennas till the cows come home and hypothesize on the
results for twice as long, but we all know that the most unlikely
collection of bits and bobs will form some sort of antenna that may, or
may not, enable QSOs one way or the other. However a successful QSO is
not scientific evidence of a "good" or "bad" antenna.
If it works, great. But do not use this as evidence of optimum antenna
performance:-)

The "suck it and see" approach may not quite equate to measured
results:-) Just my 2 cents worth.

Cheers...Bob VK2ZRE


On 1/04/2025 12:25 am, Jon via groups.io wrote:

Bob,

Would you suggest a voltage balun or current balun at antenna

feedpoint?

One ham told me that if you use a voltage balun, it can bring down the

high

noise I have on 80m.

Regarding the original question, I am tempted to think like Milt. I

see a

lot of harmonic resonance in NanoVNA tracings when I set the range high

on

purpose. In fact I use them to work higher bands. I am able to work

North

America from VU on 12m, using my 80m center-fed dipole mounted at just

5m

height and 100W, with a little bit of touching up with the N7DDC tuner.
That would be the seventh harmonic resonance!

73
Jon, VU2JO

On Mon, Mar 31, 2025 at 6:29?PM Bob Ecclestone VK2ZRE via groups.io
<becclest@...> wrote:

Hello Hobride,

Unfortunately you have not supplied a photo of your test setup.
A dipole is balanced at the feedpoint, your VNA is unbalanced.
I suspect your problem is that you do not have a balun or choke at the
antenna feedpoint to prevent the feeder from affecting the

measurement.

I won't make any guess as to why the VSWR appears lowest at 513MHz,

but

I do suggest you use a balun or choke at the antenna.

HTH...Bob VK2ZRE


On 31/03/2025 11:25 pm, Milton Engle via groups.io wrote:

You did not indicate the range of your sweep.
Try setting the sweep range to 150MHz to 190MHz, recalibrate

open/short/load, then measure.

I suspect that you will find the lowest VSWR near 171MHz, indicating

that the element lengths are a bit long.

The third harmonic of 171 is 513

Milt
N3LTQ

On Mar 31, 2025, at 03:51, hobride via groups.io <hobride=

[email protected]> wrote:

?Hello everyone,

I have bought a NANO VNA H4 to build simple dipole antennas.

Now I have made a simple dipole antenna for testing. This should be

tuned for 172 MHz. The total length is ~83 cm (2,72 feet), one leg is

~41.5

cm (1,36 feet).

When I now connect this antenna and try to measure it, the result

is a

lowest SWR (1.15) at 513 MHz.

Can this be possible? I am not a radio specialist. I am an IT guy.

I have flashed the NANO VNA H4 to the latest firmware (tried DiSlord

and Hugen) and also calibrated it.

Perhaps I need to make further settings after flashing?

--

*Dave - W?LEV*


--
Dave - W?LEV

Possibly the attachment will help.

Dave - W?LEV

On Tue, Apr 1, 2025 at 3:36?PM W0LEV via groups.io <davearea51a=
[email protected]> wrote:

Beware of most YouToob presentations. Those by the "big boys" which offer
their instruments for lots of $$$$ are good and solid. Many of those by
amateurs or "self proclaimed experts" are flawed. Take anything on YouToob
with a huge grain of salt!!

Dave - W?LEV

On Tue, Apr 1, 2025 at 1:59?PM Zack Widup via groups.io <w9sz.zack=
[email protected]> wrote:

If the video on Youtube notes that the impedance should be zero, it is
incorrect. The THRU impedance should be 50 ohms. I just checked on three
NanoVNA's, and they all measure 50 ohms.

Zack W9SZ

On Tue, Apr 1, 2025 at 8:48?AM Paolo via groups.io <paolo.vecchi=
[email protected]> wrote:

Hi, I have seen a video on Youtube…

NANOVNA analizzatore di antenne: come usarlo (
)
youtu.be ( )

( )
Inviato da iPhone

Il giorno 1 apr 2025, alle ore 15:39, Dragan Milivojevic via

groups.io

<d.milivojevic@...> ha scritto:

? Port 2 is 50Ω as it should be, why do you imagine that it would be

0?

On Tue, 1 Apr 2025 at 14:14, paolo.vecchi via groups.io

<paolo.vecchi=

[email protected]> wrote:

I buyed a nanovna H 3.6. When I try to calibrate it, after the full

procedure, if I set a Smith diagram and I connect THRU the two ports

using

the supplied cable the value is 50 ohm instead of 0. I resetted and

repeated the calibration a lot of time but with the same result. Can

you

help me? Thanks

<

Virus-free.www.avg.com
<

<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

--

*Dave - W?LEV*


--
Dave - W?LEV

--

*Dave - W?LEV*


--
Dave - W?LEV

Beware of most YouToob presentations. Those by the "big boys" which offer
their instruments for lots of $$$$ are good and solid. Many of those by
amateurs or "self proclaimed experts" are flawed. Take anything on YouToob
with a huge grain of salt!!

Dave - W?LEV

On Tue, Apr 1, 2025 at 1:59?PM Zack Widup via groups.io <w9sz.zack=
[email protected]> wrote:

If the video on Youtube notes that the impedance should be zero, it is
incorrect. The THRU impedance should be 50 ohms. I just checked on three
NanoVNA's, and they all measure 50 ohms.

Zack W9SZ

On Tue, Apr 1, 2025 at 8:48?AM Paolo via groups.io <paolo.vecchi=
[email protected]> wrote:

Hi, I have seen a video on Youtube…

NANOVNA analizzatore di antenne: come usarlo (
)
youtu.be ( )

( )
Inviato da iPhone

Il giorno 1 apr 2025, alle ore 15:39, Dragan Milivojevic via groups.io
<d.milivojevic@...> ha scritto:

? Port 2 is 50Ω as it should be, why do you imagine that it would be 0?

On Tue, 1 Apr 2025 at 14:14, paolo.vecchi via groups.io <paolo.vecchi=
[email protected]> wrote:

I buyed a nanovna H 3.6. When I try to calibrate it, after the full

procedure, if I set a Smith diagram and I connect THRU the two ports

using

the supplied cable the value is 50 ohm instead of 0. I resetted and

repeated the calibration a lot of time but with the same result. Can

you

help me? Thanks

<

Virus-free.www.avg.com
<

<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

--

*Dave - W?LEV*


--
Dave - W?LEV

QUOTE: However a successful QSO is not scientific evidence of a "good" or
"bad" antenna.
If it works, great. But do not use this as evidence of optimum antenna
performance:-)

**

I'd also add that a low SWR is also not an appropriate means of declaring
an antenna good.

Dave - W?LEV

On Tue, Apr 1, 2025 at 6:59?AM Bob Ecclestone VK2ZRE via groups.io
<becclest@...> wrote:

Hello Jon,

As you wish to use the antenna on the higher harmonics as well as 2M, I
would suggest you use ferrites to create a Common Mode Choke (CMC) as
noted by Roger.
I suspect (but do not know, I am no expert here) that it would be
difficult to build a broadband balun to cover your frequency range (x5,
x7) at TX power levels.

As for some of the other comments to this thread, I did not say that
your antenna would not work without a balun or CMC.
What I said was that without a balun or CMC, the connection of an
unbalanced VNA to a balanced dipole would not give correct measurement
results of the antenna because the feedline would become part of the
antenna measurement as also noted in other responses in this thread.

Your experience when you used a replacement "load" to do your
calibration just emphasises how critical it is to do calibrations
correctly and to treat your calibration SOLT "standards" with care and
respect.

We can measure antennas till the cows come home and hypothesize on the
results for twice as long, but we all know that the most unlikely
collection of bits and bobs will form some sort of antenna that may, or
may not, enable QSOs one way or the other. However a successful QSO is
not scientific evidence of a "good" or "bad" antenna.
If it works, great. But do not use this as evidence of optimum antenna
performance:-)

The "suck it and see" approach may not quite equate to measured
results:-) Just my 2 cents worth.

Cheers...Bob VK2ZRE


On 1/04/2025 12:25 am, Jon via groups.io wrote:

Bob,

Would you suggest a voltage balun or current balun at antenna feedpoint?
One ham told me that if you use a voltage balun, it can bring down the

high

noise I have on 80m.

Regarding the original question, I am tempted to think like Milt. I see a
lot of harmonic resonance in NanoVNA tracings when I set the range high

on

purpose. In fact I use them to work higher bands. I am able to work North
America from VU on 12m, using my 80m center-fed dipole mounted at just 5m
height and 100W, with a little bit of touching up with the N7DDC tuner.
That would be the seventh harmonic resonance!

73
Jon, VU2JO

On Mon, Mar 31, 2025 at 6:29?PM Bob Ecclestone VK2ZRE via groups.io
<becclest@...> wrote:

Hello Hobride,

Unfortunately you have not supplied a photo of your test setup.
A dipole is balanced at the feedpoint, your VNA is unbalanced.
I suspect your problem is that you do not have a balun or choke at the
antenna feedpoint to prevent the feeder from affecting the measurement.

I won't make any guess as to why the VSWR appears lowest at 513MHz, but
I do suggest you use a balun or choke at the antenna.

HTH...Bob VK2ZRE


On 31/03/2025 11:25 pm, Milton Engle via groups.io wrote:

You did not indicate the range of your sweep.
Try setting the sweep range to 150MHz to 190MHz, recalibrate

open/short/load, then measure.

I suspect that you will find the lowest VSWR near 171MHz, indicating

that the element lengths are a bit long.

The third harmonic of 171 is 513

Milt
N3LTQ

On Mar 31, 2025, at 03:51, hobride via groups.io <hobride=

[email protected]> wrote:

?Hello everyone,

I have bought a NANO VNA H4 to build simple dipole antennas.

Now I have made a simple dipole antenna for testing. This should be

tuned for 172 MHz. The total length is ~83 cm (2,72 feet), one leg is

~41.5

cm (1,36 feet).

When I now connect this antenna and try to measure it, the result is a

lowest SWR (1.15) at 513 MHz.

Can this be possible? I am not a radio specialist. I am an IT guy.

I have flashed the NANO VNA H4 to the latest firmware (tried DiSlord

and Hugen) and also calibrated it.

Perhaps I need to make further settings after flashing?

--

*Dave - W?LEV*


--
Dave - W?LEV

All info here is accurate. BUT, to save time, calculate the "electrical"
wavelength needed mathematically for the "rough" estimate. Wavelength =
300/frequency (MHz) multiplied by the specified Velocity Factor from the
manufacturer. Then, add several inches for "tuning" via the VNA.

Michael L Robinson, KC0TA

“In the beginning of a change the Patriot is a scarce man, and brave, and
hated and scorned. When his cause succeeds, the timid join him, for then it
costs nothing to be a Patriot.” ― Mark Twain

When Tyranny becomes Law, Revolution becomes Duty!






On Sun, Mar 30, 2025 at 2:44?PM Team-SIM SIM-Mode via groups.io <sim31_team=
[email protected]> wrote:

Hi
a Calibrated smith diagram can show you easily the serial resonance
frequency and the parallele one ( Xr = 0 Omh ) ,
- use the 401 sweep points option to have maximum frequency accuracy .
- Stimulus band should be selected to be the minimum needed .
- Calibration and measurement prefered after at least 10 minutes for
thermal stability .

you can use open coax terminaison or short one , they should give
approximatly the same results .

73's Nizar.

On Mon, Mar 31, 2025 at 03:20 PM, Joe WB9SBD wrote:

The Balun Craze is a new Generation thing. Got licensed in 1975, Never
ever heard of a Balun.
All my dipoles were direct feed.
Only till recently has the myth of a dipole without a balun will not work.

When I started in ham radio, 46 years ago, indeed almost nobody used baluns with dipole antennas. Nowadays instead it's very common to use them, and there are at least two good reasons for this change!

One reason is interference between radio equipment and other stuff in the home. Computers, switching power supplies, TVs, even refrigerators and lamps. When no balun is used, the feedline is part of the antenna, so the antenna extends into the shack and the home's electrical wiring, severely worsening the interference situation. With a balun that's working ideally, the feedline does not radiate, and does not receive signals, so is not part of the antenna. That moves the actual antenna out of the home, away from the switching power supplies and other stuff, reducing the interference both ways. Back before the 1980s this wasn't such a big factor, because there were no switching power supplies, no computers, no LED lamps, no CFL lamps with electronic ballasts, no LAN, and so on. TVI was the only point of concern, and sometimes handled by establishing time schedules for ham operation and for TV viewing. But today it's an important factor, because there are so many interference-causing and interference-sensitive things that it's not acceptable to turn them all off by a schedule.

The other reason is how hams assess the condition and usability of their antennas. In the "good old times", the test was whether the transmitter could be loaded up into that antenna, without arcing, and how many contacts it produced. The antenna would be cut by trial and error to such a length that it worked well enough with that one specific feedline, in its fixed position. At most a ham might measure the SWR, but many didn't even have an SWR meter. Today instead, with instruments like the nanoVNA, hams have become scientists, trying to understand exactly what's going on, and will discover things like the antenna being resonant outside the band and operating on one the sides of the resonance dip, or that moving around the coax cable will change the SWR, or that adding even a little piece of coax will drastically change the impedance, shifting the resonant frequency. So they prefer to use baluns, to reduce the sensitivity of the antenna's parameters to feedline conditions, in order to be able to at least begin to understand what's happening with their antennas, and to achieve a setup that works more like theory tells.

I began using baluns in 1989, when I got into packet radio, and needed to run a computer at the same time as a radio, and interconnect the two, hopefully without causing feedback loops.

About that 172MHz dipole, I would expect it to measure differently according to its position relative to the nanoVNA and other stuff, to be sensitive to feedline length, etc. The usual stuff. If a balun is added, I would suggest a current balun, since we don't know how the antenna will be oriented, what will be close to it, but we do know that we want the lowest possible common-mode current on the feedline.

Thanks a lot

Inviato da iPad

If the video on Youtube notes that the impedance should be zero, it is
incorrect. The THRU impedance should be 50 ohms. I just checked on three
NanoVNA's, and they all measure 50 ohms.

Zack W9SZ

On Tue, Apr 1, 2025 at 8:48?AM Paolo via groups.io <paolo.vecchi=
[email protected]> wrote:

Hi, I have seen a video on Youtube…

NANOVNA analizzatore di antenne: come usarlo (
)
youtu.be ( )

( )
Inviato da iPhone

Il giorno 1 apr 2025, alle ore 15:39, Dragan Milivojevic via groups.io
<d.milivojevic@...> ha scritto:

? Port 2 is 50Ω as it should be, why do you imagine that it would be 0?

On Tue, 1 Apr 2025 at 14:14, paolo.vecchi via groups.io <paolo.vecchi=
[email protected]> wrote:

I buyed a nanovna H 3.6. When I try to calibrate it, after the full

procedure, if I set a Smith diagram and I connect THRU the two ports

using

the supplied cable the value is 50 ohm instead of 0. I resetted and

repeated the calibration a lot of time but with the same result. Can you

help me? Thanks

<>
Virus-free.www.avg.com
<>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

Grazie
Inviato da iPhone

Hi, I have seen a video on Youtube…

NANOVNA analizzatore di antenne: come usarlo ( )
youtu.be ( )

( )
Inviato da iPhone

Per avere il valore zero sul diagramma di Smith (puntatore alla estrema
sinistra) devi mettere il connettore SHORT.


Il Mar 1 Apr 2025, 14:14 paolo.vecchi via groups.io <paolo.vecchi=
[email protected]> ha scritto:

I buyed a nanovna H 3.6. When I try to calibrate it, after the full
procedure, if I set a Smith diagram and I connect THRU the two ports using
the supplied cable the value is 50 ohm instead of 0. I resetted and
repeated the calibration a lot of time but with the same result. Can you
help me? Thanks

Port 2 is 50Ω as it should be, why do you imagine that it would be 0?

On Tue, 1 Apr 2025 at 14:14, paolo.vecchi via groups.io <paolo.vecchi=
[email protected]> wrote:

I buyed a nanovna H 3.6. When I try to calibrate it, after the full
procedure, if I set a Smith diagram and I connect THRU the two ports using
the supplied cable the value is 50 ohm instead of 0. I resetted and
repeated the calibration a lot of time but with the same result. Can you
help me? Thanks

I buyed a nanovna H 3.6. When I try to calibrate it, after the full procedure, if I set a Smith diagram and I connect THRU the two ports using the supplied cable the value is 50 ohm instead of 0. I resetted and repeated the calibration a lot of time but with the same result. Can you help me? Thanks

Hello Jon,

As you wish to use the antenna on the higher harmonics as well as 2M, I would suggest you use ferrites to create a Common Mode Choke (CMC) as noted by Roger.
I suspect (but do not know, I am no expert here) that it would be difficult to build a broadband balun to cover your frequency range (x5, x7) at TX power levels.

As for some of the other comments to this thread, I did not say that your antenna would not work without a balun or CMC.
What I said was that without a balun or CMC, the connection of an unbalanced VNA to a balanced dipole would not give correct measurement results of the antenna because the feedline would become part of the antenna measurement as also noted in other responses in this thread.

Your experience when you used a replacement "load" to do your calibration just emphasises how critical it is to do calibrations correctly and to treat your calibration SOLT "standards" with care and respect.

We can measure antennas till the cows come home and hypothesize on the results for twice as long, but we all know that the most unlikely collection of bits and bobs will form some sort of antenna that may, or may not, enable QSOs one way or the other. However a successful QSO is not scientific evidence of a "good" or "bad" antenna.
If it works, great. But do not use this as evidence of optimum antenna performance:-)

The "suck it and see" approach may not quite equate to measured results:-) Just my 2 cents worth.

Cheers...Bob VK2ZRE

Yes,a dipole will work without a balun. But it is not a dipole anymore. The outer surface of your coax shield becomes part of the antenna system. This can give inaccurate results with the VNA. In real world usage it will distort the radiation pattern of the antenna and can provide a path for RFI in unexpected places. It's not rocket science but it *is* radio science.

--

73

-Jim
NU0C

Your first link redirects to the same url the OP posted but I got to ask:
What is your issue with the paper being hosted in Bosnia&Hertzegovina,
the paper originated there.

On Mon, 31 Mar 2025 at 20:44, Jim Lux via groups.io <jimlux=
[email protected]> wrote:

Other sources that are in other countries than Bosnia Hertzegovina







The authors have a number of other interesting "measure component with a
VNA"


Measuring impedances of DC-biased inductors by using vector network
analyzers

I suspected the 50 Ohm calibration resistor and ordered two new ones.
After recalibration and measurement, the SWR is 1.26 at 172 MHz and 1.65 at 522 MHz.
Both measurements with SOL calibrated center frequencies 172 span 50 MHz and center 522 MHz span 50 MHz

that is much more plausible to me, i'm right?

I think that was the reason.

thanks for your support

Other sources that are in other countries than Bosnia Hertzegovina







The authors have a number of other interesting "measure component with a VNA"

Measuring impedances of DC-biased inductors by using vector network analyzers

The SWR for a 50 Ohm cable will depend on the feedpoint impedance at the end of the cable. The impedance will depend on the antenna dimensions, its height, and its proximity to the environment. If the antenna is supported horizontally, its impedance at resonance could vary from a few Ohms to a maximum around 90 Ohms and then down to about 72 Ohms as the height is increased. If you are seeing a minimum SWR at your operating frequency, the length of the antenna is at or very close to a half-wave. Sometimes you can bend the ends of the antenna towards the ground and reduce their length to bring the impedance to 50 Ohms and an SWR of 1.0.

You need to calibrate your coax SOL at the far end, so your readings look
like your antenna is at the vna and not some distance away.9

On Mon, Mar 31, 2025, 12:58 AG6CX via groups.io <edwmccann=
[email protected]> wrote:

Maynard and others:

You and we were most fortunate to be initiated with one of the most robust
sunspot cycles of modern times in 1957!!

Same story at pre-Nano VNA KN1CJO in southern Maine. Worked all over the
place, including all TV sets in the neighborhood.

Antenna was classic Windom, usual length, but fed with 300 feet of single
wire to bannana plug into the DX-20 antenna port, me serving as T-R relay.

We are equally fortunate to still be able to remember all that, and be
alive to write about

Ed McCann
AG6CX
Sausalito

On Mar 31, 2025, at 8:45?AM, Maynard Wright, P. E., W6PAP via groups.io

<ma.wright@...> wrote:

?I got my Novice license in 1957 and used a single wire routed out the

window and up to the brick chimney and then across the yard about 100 feet
to a pole. It worked fine, with my best DX using a Knight Kit 50 watt
(input) transmitter being an Argentine station in Antarctica. I worked a
few Japanese stations and some South Americans from my QTH in Northern
California, never realizing that my antenna was really awful.

When I upgraded from Novice to Conditional in 1958, I used a 100TH with

the same antenna to work folks on AM and CW. With either transmitter, I
had to stand up and throw a knife switch on the wall to go from receive to
transmit.

I also still have a bunch of QSL cards from that era that bring back

nice memories.

The important thing was that my Knight Kit with a pi-network and my

100TH with a swinging link coupler didn't care much about the SWR. I
simply tuned for about a 10% drop in plate current and no red glow from the
100TH and everything worked fine. With a modern transmitter that wants
something approximating 50 ohms, such an antenna would require a tuner and
the losses in the tuner might use up a lot of the generated RF energy.

My most modern rigs here still use pi-networks, which is why I can get

away with using a wire in the attic draped over air conditioning ducts and
water pipes and work DX, not like a real DXer would want, but enough for a
casual guy.

73,

Maynard
W6PAP

On 3/31/25 08:07, Jon via groups.io wrote:
Joe,
I got licensed a decade after you and did not have a chance to use a

balun

or 50 ohms coax then. My 40 and 80m dipoles were fed by 75 ohms TV

cable. I

did not have an SWR meter either. Still I could work a lot of DX

including

a few W land stations with my homebrew 3 x 807 radio, 120W CW and

straight

key. I still have a couple of W land QSL cards in my precious

collection.

73
Jon, VU2JO

On Mon, Mar 31, 2025 at 7:50?PM Joe WB9SBD via groups.io <nss=
[email protected]> wrote:
Yup!
The Balun Craze is a new Generation thing. Got licensed in 1975, Never
ever heard of a Balun.
All my dipoles were direct feed.
Only till recently has the myth of a dipole without a balun will not

work.

just like a 40 meter Dipole will not work on 15 meters!

tell that to all the Novices that got their license in the 70's.

Joe WB9SBD

On 3/31/2025 8:53 AM, Zack Widup via groups.io wrote:

I have never seen a problem feeding a dipole directly with an

unbalanced

feedline. The last dipoles I had up (which were for 40 and 30 meters)

were

just fed by connecting the two leads of the coax directly to the

antenna

wires attached to an insulator at the center of the antenna. SWR in

both

cases, when the antenna was trimmed, were around 1.05:1. And I worked

180

countries on 40 m CW with that antenna and Japan fairly often on 30 m

CW.

Zack W9SZ

<

Virus-free.www.avg.com
<

<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

On Mon, Mar 31, 2025 at 7:59?AM Bob Ecclestone VK2ZRE via groups.io
<becclest@...> wrote:

Hello Hobride,

Unfortunately you have not supplied a photo of your test setup.
A dipole is balanced at the feedpoint, your VNA is unbalanced.
I suspect your problem is that you do not have a balun or choke at

the

antenna feedpoint to prevent the feeder from affecting the

measurement.

I won't make any guess as to why the VSWR appears lowest at 513MHz,

but

I do suggest you use a balun or choke at the antenna.

HTH...Bob VK2ZRE


On 31/03/2025 11:25 pm, Milton Engle via groups.io wrote:

You did not indicate the range of your sweep.
Try setting the sweep range to 150MHz to 190MHz, recalibrate

open/short/load, then measure.

I suspect that you will find the lowest VSWR near 171MHz, indicating

that the element lengths are a bit long.

The third harmonic of 171 is 513

Milt
N3LTQ

On Mar 31, 2025, at 03:51, hobride via groups.io <hobride=

[email protected]> wrote:

?Hello everyone,

I have bought a NANO VNA H4 to build simple dipole antennas.

Now I have made a simple dipole antenna for testing. This should be

tuned for 172 MHz. The total length is ~83 cm (2,72 feet), one leg is

~41.5

cm (1,36 feet).

When I now connect this antenna and try to measure it, the result

is a

lowest SWR (1.15) at 513 MHz.

Can this be possible? I am not a radio specialist. I am an IT guy.

I have flashed the NANO VNA H4 to the latest firmware (tried

DiSlord

and Hugen) and also calibrated it.

Perhaps I need to make further settings after flashing?