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WHAT??? All that power being lost????

Seriously, a 2:1 SWR will only loose 11.1% of the power.? So a 100 watt station will give you 88.9 watts of ERP (Less cable loss and plus antenna gain).

Really not worth loosing time on the air.

73, Joe, K1ike

My.....my........ For heaven's sake......! What concerns about a meager
2:1 SWR!! Just go with it, get on the air, and enjoy.

Dave - W?LEV

On Thu, Nov 14, 2024 at 7:15?PM DP via groups.io <dpoinsett=
[email protected]> wrote:

Hi Barry K3EUI

You and others make an excellent point about the practical acceptability
of of a 2:1 SWR. I agree that for the casual ham using commonly available
equipment, it's probably not a big deal especially on the lower HF
frequencies.

You are correct that by adding an inductor across the antenna terminals
and altering the antenna dimensions, the feedpoint impedance can be
transformed to 50+j0 ohms, but the cut-and-try approach will be no easier
than any of the other suggested methods. Also, just adding an inductor will
not automatically increase the impedance. Depending in the initial antenna
impedance, it may go up or down.

If we stay with Bill's 25-ohm example, the antenna length and angle
between each leg could be adjusted to get a 25-j25 feedpoint impedance at
say 7.15 MHz. Adding a 1.1 uH inductor across the antenna terminals will
then get you to 50+j0 ohms. Other combinations could work, too. Of course
whatever combination he comes up with will only work at the design
frequency.

Dave NU8A

--

*Dave - W?LEV*


--
Dave - W?LEV

For Barry K3EUI

"Also, just adding an inductor will not automatically increase the impedance. Depending in the initial antenna impedance, it may go up or down."

I should have said that just adding the inductor will not automatically increase the R value in R+/-jX. Depending on the initial antenna impedance, the R value may go up or down.

Dave NU8A

Hi Bill WA2WIO,

Your antenna geometry and dimensions can be adjusted to achieve a wide range of feedpoint impedances for a specific frequency. Once the shape and dimensions are set, the complex feedpoint impedance (R+/-jX) will be very different on different frequencies.

The three methods described in my earlier post can be adapted to transform almost any complex impedance to 50 ohms on any band, but a specific design will only work near its target frequency. The same is true for LC circuits used in antenna tuners. The parallel 1/4-wave coax method described earlier is also frequency-specific and limited to a source impedance of 25-ish + j0 ohms. (Lengths other than 1/4-wave could work for a specific set of complex impedances, but this too would be frequency- specific.)

Imbalance in the antenna feedpoint current can be intended or not. There are both good and bad consequences. Also, it's best to keep RF current off the outside shield of the coax, and there are multiple ways to achieve it, but neither of those things are the topic of this thread so I'll just leave it at that for now.

In my examples #2 and #3, the stubs are connected parallel to the coax at the far end away from the antenna. (You can see it represented schematically in the attachments previously sent. The antenna load is on the left.) Example 2 uses a shorted stub. Example 3 uses an open stub. A shorted stub acts like an inductor and could be substituted with an equivalent inductor value. An open stub acts like a capacitor and could be substituted with an equivalent capacitor value.

Information on impedance matching using these techniques appear in the ARRL Handbook and ARRL Antenna Book, but one of the best sources I can recommend is the YouTube videos by Larry Benko W0QE. In many ways his videos are a guide to using SimSmith (now called SimNEC), but he's so good at explaining the underlying principles in simple terms that it might be the good tutorial you seek.

Dave NU8A

Hi Barry K3EUI

You and others make an excellent point about the practical acceptability of of a 2:1 SWR. I agree that for the casual ham using commonly available equipment, it's probably not a big deal especially on the lower HF frequencies.

You are correct that by adding an inductor across the antenna terminals and altering the antenna dimensions, the feedpoint impedance can be transformed to 50+j0 ohms, but the cut-and-try approach will be no easier than any of the other suggested methods. Also, just adding an inductor will not automatically increase the impedance. Depending in the initial antenna impedance, it may go up or down.

If we stay with Bill's 25-ohm example, the antenna length and angle between each leg could be adjusted to get a 25-j25 feedpoint impedance at say 7.15 MHz. Adding a 1.1 uH inductor across the antenna terminals will then get you to 50+j0 ohms. Other combinations could work, too. Of course whatever combination he comes up with will only work at the design frequency.

Dave NU8A

its just several dipoles in parallel on the higher bands fed on the gap (almost similar to a fan dipole)

except on 10m where it is 3 quarterwave ... on 40m it is a quarterwave against bent radial (the gap is "bridged" with the folded coax stup inside)... on 80m its a loaded vertical where the cap on the top is transformed to a coil via the folded coax inside ... so it is NOT a colinear design

dg9bfc sigi

Am 13.11.2024 um 07:48 schrieb Colin McDonald via groups.io:

Where in the H4 source code are MS5351m vs Si5351 configuration adjusted?

To measure the loss/gain of an antenna, both in transmission and reception, you will have to do it by comparing it with another one. For this, a field strength meter will be useful; the nanoVNA is a vector network analyzer, it is not designed for that purpose.
--
ALVARO, EA8ARX

On Wed, Nov 13, 2024 at 10:40 PM, Maynard Wright, P. E., W6PAP wrote:

Fairly complex charts for determining complex hyperbolic functions were used
in the Bell System to make calculations using the exact expressions before
computers were widely available.

One of these was the "Clarke Calculator" invented by Edith Clarke:
She also designed the turbine system for the Hoover Dam.
73, Don NVGU

Since I am on Windows Seven, I use nanovna-saver 0.3.8. My NanoVNA is

DEEPELEC NanoVNA-F 4.3" HW2.3 HW3.1 Firmware 1.05 (Oct 31, 2022)

I observe:

1/ To succeed, every time, the NanoVNA <-> PC connection, you must:

- Start the nanoVNA
- Connect the USB cable to the PC
- Start nanovna-saver
- clic [Connect] on nanovna-saver

If nanovna-saver is launched first, it does not work every time

2/ Then, before any measurements or calibration, it is essential to do in the nanoVNA menu
CALIBRATE
RESET
This operation is independent of the reloading of a previous calibration in nanovna-saver.

The need for RESET on the NanoVNA surprises me. Why doesn't nanovna-saver (my version) do it itself?
--
F1AMM
Fran?ois

On Wed, Sep 25, 2024 at 03:33 AM, @VK4JJ wrote:

Some further info:

I can connect to the device via USB and PuTTY and get some sort of output
(attached).

But when I run a scan command, it freezes.

Check SI5351 generator I2C bus exchange

One problem with calculations at audio frequencies is that most transmission lines exhibit complex characteristic impedances below around 300 kHz or thereabouts. Telephone cable pairs, if untreated by series inductive loading, exhibit Zo with angles very close to -45 degrees across the voice frequency band.

So the high frequency approximations that lead to convenient expressions for SWR and reflection coefficient are not applicable for most audio applications. Telephone transmission engineers rarely used them, employing instead return loss and reflection loss. Fairly complex charts for determining complex hyperbolic functions were used in the Bell System to make calculations using the exact expressions before computers were widely available.

73,

Maynard
W6PAP

You don't often see Smith charts at audio frequencies because transmission-line techniques are less common, as is complex impedance matching in general. No reason why they couldn't be supported, of course.

The QuantAsylum QA403 is very nice, hardware-wise, for those who aren't content with sound cards. More expensive than a NanoVNA but still well under four digits.

-- john, KE5FX

The major claim to fame of this type of antenna is not "gain" or
"directivity", but coverage of all the amateur HF bands with one antenna
with a single feedline. It is a compromise to accomplish that end. I
seriously doubt it has any "gain" over a single-band properly installed and
fed 1/4-wavelength vertical radiator.

Dave - W?LEV

On Wed, Nov 13, 2024 at 12:23?PM Jim Lux via groups.io <jimlux=
[email protected]> wrote:

Indeed but modeling multiband antennas with traps and internal components
with multiple coupling mechanisms can be full of interesting challenges
Sent via the Samsung Galaxy S24, an AT&T 5G smartphone
-------- Original message --------From: "Colin McDonald via groups.io"
<colinrmcdonald@...> Date: 11/12/24 11:21 PM (GMT+00:00)
To: [email protected] Subject: Re: [nanovna-users] measuring gain
of multi band vertival antenna (GAP Titan DX) This isn't something the
NanoVNA can measure. Any free antenna modelling software can tell you
though. Just download a flavor and enter all the antenna specifications it
asks for. It'll tell you what the angle of radiation is and where the
strongest gain is theoretically.Otherwise, you can use a field strength
meter to compare a dipole or a ground mounted quarter wave with radials to
the titan.However, a field strength meter won't always give you the most
accurate results if the antenna has an angle of radiation that passes over
where you are taking the measurements. Antennas present gain at specific
angles, what are called lobes. Depending on the type of antenna, quarter
wave, half wave, 5/8s wave, full wave etc the angle will be different.
It'll change depending on whether the antenna is a ground mounted vertical,
elevated, how many ground radials you have and of course near by
objects.Antenna modelling software calculates all of this information and
spits out data that can be useful to you.#1 is usually ground radials for a
ground mounted vertical antenna regardless of the radiating elements wave
length. The more quarter wave on the lowest operating frequency ground
radials you have, up to about 128, the better the antenna will perform.A
google search will also tell you what the estimated gain over a dipole or
gain over an isotropic radiator is for the dx titan antenna. Gain is
measured as a comparison in DB to either a dipole or an isotropic radiator.
Most manufacturers use DBI because it yields a larger number which makes
people believe the antenna has more gain. The antenna isn't an amplifier,
there is no magic going on that turns your 100 watts into a KW or
something. There is effected radiated power, but that is based entirely on
lobe radiation and a direct comparison of the nulls to the strongest lobes
of a particular antenna.None of which can be measured with a
NanoVNA.Theoretical math and formulas are used in the modelling software as
apposed to direct electrical measurements.73Colin VA6GGOn 2024-11-12 2:47
p.m., Michael E Wilson Sr via groups.io wrote:> Has anyone measured or
seen the gain factors for an antenna like the Tital DX. I have used one for
16 years, moved it to 4 different locations and it has never faild. But I
am curious about its gain on the divverent bands and would like to get a
measurement. Then may be I could see what is needed to improve it
operationj. Any information as to what equipment would be needed and the
procedures to follow would be appreciagted.>> Thanks.> 73> Mike Wilson>
KE5WCT> Daingerfield, Morris County, Texas (EM23ob)>>> >>

--

*Dave - W?LEV*


--
Dave - W?LEV

Try 1.2.42 Installed today, works fine (exc. wonky conn. to touch screen), great instructions here:

--
I_B_Nbridgema

That's actually the main purpose of calibrating a VNA, to remove everything
from the measurement except the DUT.

73,
-de James/AC0CW

On Wed, Nov 13, 2024, 13:13 Akai Moto via groups.io <akai.moto=
[email protected]> wrote:

Is it a viable method to do calibration of the VNA with a transmission
line attached, so that when the DUT is attached to end of that line the
measurements are true measurements of just the DUT?

Oops! Those who might want it, get it while you can - or else you will have to ask the Wayback Machine.

More and more creators of well-known software are retiring. Many of them go the extra mile when they do, and put the source code in the public domain, or waive the cost of formerly commercial programs, or at least warn their users to update while they can. Thanks to all of them!

A relatively recent case was Micro-CAP. I had been using the student/hobby version for years, and the end-of-support free release allowed me to get the full version.

When I retire, I intend to release the source code of the (few) programs I have written. So someone else can continue development, if anyone wants.

Yes; in fact I had to do this to calibrate measurements made on a 1296 MHz
bias tee using microstrip transmission lines.

Zack W9SZ

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

On Wed, Nov 13, 2024 at 12:13?PM Akai Moto via groups.io <akai.moto=
[email protected]> wrote:

Is it a viable method to do calibration of the VNA with a transmission
line attached, so that when the DUT is attached to end of that line the
measurements are true measurements of just the DUT?

Yes. Instead of doing the OSL calibration at the unit, do the same at the
end of the coaxial feedline. Outside of a bit of loss due to the coax,
then your measurement plane will be at the end of the feedline.

Dave - W?LEV

On Wed, Nov 13, 2024 at 6:13?PM Akai Moto via groups.io <akai.moto=
[email protected]> wrote:

Is it a viable method to do calibration of the VNA with a transmission
line attached, so that when the DUT is attached to end of that line the
measurements are true measurements of just the DUT?

--

*Dave - W?LEV*


--
Dave - W?LEV

Is it a viable method to do calibration of the VNA with a transmission line attached, so that when the DUT is attached to end of that line the measurements are true measurements of just the DUT?