Re: Nano VNA of a modified 40m hor loop NVIS antenna
40-meters between your target times of 1000 to 1400 local will be
problematic if the fof2 is not at or above 7-MHz. Here in N. Colorado, of
late, it has been, but over the last couple of years during the lull
between Solar Cycles 24 and 25, NVIS was impossible due to the low fof2
which came in lower than 5 MHz. For a look at the fof2 in your area, check
the following:
Of course, I regularly use the Boulder, Colorado, ionogram as it's only
some 30-miles to my south.
Dave - W?LEV
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On Wed, Sep 6, 2023 at 11:58?AM Barry K3EUI <k3euibarry@...> wrote: JJ Night
To answer your question¡
There is nothing special about this antenna, other than it is a closed
LOOP of 140 ft heavy wire #10 because I had a few hundred feet of this wire.
I wanted good daytime NVIS antenna for prop of only a few hundred miles
from Phila around 10AM to 2 PM.
I was not interested in a low-angle DX signal for evening use (I have a
vertical that does that well)
The amount of wire did not matter too much (120-140 ft to start).
I feed this with about 75 ft of RG213 (nothing special)
The shape is a rectangle, only 20 ft or so above ground. I had a few big
strong trees as tie points.
I tried a 4:1 balun at first (thinking impedance of 100 ohms) and that did
not work well.
I replaced that with a simple 1:1 BALUN (choke).
At the low height above ground, I expected a lower impedance than putting
it up 50 ft.
I could attach the Nano VNA right at the feedpoint - direct - to avoid the
feedline messing with impedance.
I then hooked it up to a CLC Tuner (in my shack) in case the SWR was high
at the digi part of the band.
Because I had about 140 ft wire in the loop, the resonant point was just
below 7 MHz (about 6.8 MHz).
It worked fine for two weeks, but then I thought maybe I could improve it
by shortening it.
I pruned it back about 10 feet (harder to do for me on a 90 degree day)
and then I saw that the minimum SWR fell around 7.1 MHz, right where I
wanted it.
The NANO VNA that I own is already 3 years old (Amazon model) and I¡¯m
using NANO VNA SAVER app on a Win10 (10 yr old) desktop. I had to make the
CALIB first with a 3-30 MHz span at a 10x mag. That took a few minutes to
do the OPEN, SHORT, and 50 0hm LOAD with the standards that came with the
rig.
I did a sweep from 3-30 MHz using the 50 ohm standard and everything
looked perfect on the 6 graphs.
That was reassuring!
The closed loop works far better than a pair of Hamsticks mounted
horizontally (14 ft total). Well, obviously!
It works just about as well as a simple 66 ft Inverted V center-fed dipole
(my standard) but I see much less QSB on the closed loop than from the
dipole. I like to use 7047 kHz W1AW CW bulletins as my standard to compare
antennas at 9AM to 10AM. And¡ it helps me copy CW by ear.
So nothing special about anything that I did.
I put in a CLC tuner in my shack, and this does sharpen up all of the
graphs, but I did not really need it.
My goal: see if I could build a better DAYTIME NVIS antenna for low part
of the 40m band.
I love the sound card digi modes and FLDIGI and am working on a new 40m
EMCOMM digi mode net which should begin on October 1st: Mid-Atlantic 40m
NBEMS net (7068 kHz vfo).
We plan to run this net every Sunday at 10AM to 11AM for a few months to
see how well ¡°fickle forty¡± does at that hour with THOR22 (checkin) and
THOR56 (traffic). We know that 80m collapses by 10 AM for NVIS.
I really did not need a Nano VNA to build and test this antenna. I am now
doing A/B tests to see if folks I work on 40m digi modes can hear any
differences between the closed loop and Inverted V simple dipole.
I took the back-to-back Hamsticks down (may be good for a portable setup)
And I still have a 36 ft vertical with two above ground radials (upside
down T) for evening DX.
What are you trying to accomplish in your antenna?
Without the SAVER software, I¡¯d be lost (color blind).
de k3eui Barry
near Philly
Sept 06 2023
-- *Dave - W?LEV*
--
Dave - W?LEV
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Re: Nano VNA of a modified 40m hor loop NVIS antenna
Capacitor,inductor,capacitor Ok... with a capacitor, inductor, capacitor + inducteur you can do a fixed two band matching network :) Thank -- F1AMM Fran?ois -----Message d'origine----- De la part de Jim Lux Envoy¨¦ : mercredi 6 septembre 2023 15:49
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Re: Nano VNA of a modified 40m hor loop NVIS antenna
a closed LOOP of 140 ft heavy wire #10
I feed this with about 75 ft of RG213 (nothing special)
The shape is a rectangle, only 20 ft or so above ground. I have almost the same antenna as you. Over 40 m no station arrives harder than on my trap doublet at 12 m height. In general, a station arrives between -6dB and -10dB on the loop than on the doublet. In the other direction, for the correspondent, the observation is the same. On the other hand, in reception, I almost always notice an improvement in the signal-to-noise ratio. I am thinking that no NVIS propagation is possible in my region (France) over 40 m. In France, the 1 to 6 MHz band is generally usable for NVIS propagation, while in the tropics it is rather the 4 to 12 MHz band () Is it possible on Philadelphie ? Over 20 m (14 MHz) this antenna significantly improves the received signal, often by +6dB to +10dB. I was not able to reliably test the signal received from my correspondent.... The antenna is equipped, at the coaxial cable / antenna connection, with a double 'L' adapter of my design - production. 73 -- Fran?ois -----Message d'origine----- De la part de Barry K3EUI Envoy¨¦ : mercredi 6 septembre 2023 13:59
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Re: Nano VNA of a modified 40m hor loop NVIS antenna
Capacitor,inductor,capacitor
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On Sep 6, 2023, at 6:10 AM, Fran?ois <18471@...> wrote:
?
I put in a CLC tuner in my shack,
Please wat is a "CLC tuner" ?
--
F1AMM
Fran?ois
-----Message d'origine----- De la part de Barry K3EUI
Envoy¨¦ : mercredi 6 septembre 2023 13:59
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Re: Nano VNA of a modified 40m hor loop NVIS antenna
I put in a CLC tuner in my shack, Please wat is a "CLC tuner" ? -- F1AMM Fran?ois -----Message d'origine----- De la part de Barry K3EUI Envoy¨¦ : mercredi 6 septembre 2023 13:59
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Re: Nano VNA of a modified 40m hor loop NVIS antenna
JJ Night
To answer your question¡
There is nothing special about this antenna, other than it is a closed LOOP of 140 ft heavy wire #10 because I had a few hundred feet of this wire.
I wanted good daytime NVIS antenna for prop of only a few hundred miles from Phila around 10AM to 2 PM.
I was not interested in a low-angle DX signal for evening use (I have a vertical that does that well)
The amount of wire did not matter too much (120-140 ft to start).
I feed this with about 75 ft of RG213 (nothing special)
The shape is a rectangle, only 20 ft or so above ground. I had a few big strong trees as tie points.
I tried a 4:1 balun at first (thinking impedance of 100 ohms) and that did not work well.
I replaced that with a simple 1:1 BALUN (choke).
At the low height above ground, I expected a lower impedance than putting it up 50 ft.
I could attach the Nano VNA right at the feedpoint - direct - to avoid the feedline messing with impedance.
I then hooked it up to a CLC Tuner (in my shack) in case the SWR was high at the digi part of the band.
Because I had about 140 ft wire in the loop, the resonant point was just below 7 MHz (about 6.8 MHz).
It worked fine for two weeks, but then I thought maybe I could improve it by shortening it.
I pruned it back about 10 feet (harder to do for me on a 90 degree day) and then I saw that the minimum SWR fell around 7.1 MHz, right where I wanted it.
The NANO VNA that I own is already 3 years old (Amazon model) and I¡¯m using NANO VNA SAVER app on a Win10 (10 yr old) desktop. I had to make the CALIB first with a 3-30 MHz span at a 10x mag. That took a few minutes to do the OPEN, SHORT, and 50 0hm LOAD with the standards that came with the rig.
I did a sweep from 3-30 MHz using the 50 ohm standard and everything looked perfect on the 6 graphs.
That was reassuring!
The closed loop works far better than a pair of Hamsticks mounted horizontally (14 ft total). Well, obviously!
It works just about as well as a simple 66 ft Inverted V center-fed dipole (my standard) but I see much less QSB on the closed loop than from the dipole. I like to use 7047 kHz W1AW CW bulletins as my standard to compare antennas at 9AM to 10AM. And¡ it helps me copy CW by ear.
So nothing special about anything that I did.
I put in a CLC tuner in my shack, and this does sharpen up all of the graphs, but I did not really need it.
My goal: see if I could build a better DAYTIME NVIS antenna for low part of the 40m band.
I love the sound card digi modes and FLDIGI and am working on a new 40m EMCOMM digi mode net which should begin on October 1st: Mid-Atlantic 40m NBEMS net (7068 kHz vfo).
We plan to run this net every Sunday at 10AM to 11AM for a few months to see how well ¡°fickle forty¡± does at that hour with THOR22 (checkin) and THOR56 (traffic). We know that 80m collapses by 10 AM for NVIS.
I really did not need a Nano VNA to build and test this antenna. I am now doing A/B tests to see if folks I work on 40m digi modes can hear any differences between the closed loop and Inverted V simple dipole.
I took the back-to-back Hamsticks down (may be good for a portable setup)
And I still have a 36 ft vertical with two above ground radials (upside down T) for evening DX.
What are you trying to accomplish in your antenna?
Without the SAVER software, I¡¯d be lost (color blind).
de k3eui Barry
near Philly
Sept 06 2023
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Re: NanoVNA-APP chart options question
Hi Mark, Roger,
For NanoVNA-App (DiSlord version) these informations are calculated, but not plotted.
They are displayed on the Info Panel (info button must be turned on), right side at the lower part. Compared to my Libre Office calculation sheet, values are perfectly relevant.
73 Jean-Roger
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Re: Nano VNA of a modified 40m hor loop NVIS antenna
You can¡¯t go wrong with a loop. Would you walk me through how you went about testing it and tuning it? I have to build a new one myself and I¡¯m curious how you connected it to your vna. JJ Knight N5MNX ________________________________ From: [email protected] < [email protected]> on behalf of Barry K3EUI <k3euibarry@...> Sent: Tuesday, September 5, 2023 2:26:28 PM To: [email protected] < [email protected]> Subject: [nanovna-users] Nano VNA of a modified 40m hor loop NVIS antenna How are folks doing on a 40m NVIS antenna for daytime short-range COMS? A bit more tweaking of my 40m closed LOOP NVIS antenna for 7075 kHz Less than 1.5:1 SWR across 40m band Over 50dB return loss at resonant frequency 7075 kHz The Nano VNA graphs make this loop antenna easy to "tune up" I'm ready to try it out: 7068 kHz Sunday at 10 AM EDT with THOR 22 This antenna is about 2-3 S-units (15dB) stronger than back-to-back 40m 7 ft Hamsticks and also a few S-units stronger than my 40m vertical (34 ft lashed to a tree) on daytime coms de k3eui
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Re: Not available at Ali Express / Zeenko
Anyone with basic IT expertise will tell you the same. On Tue, 5 Sept 2023 at 17:16, Julio VE3FH via groups.io <ve3fh@...> wrote:
No, none of my computers and other devices has been compromised.
I will make no further comments on this pointless exchange because it has veered way off topic for the reflector plus you are dead set on exonerating PayPal and any other "reputable" payment processors of any responsibility.
73,Julio VE3FH
On Thursday, August 31, 2023 at 09:02:22 p.m. EDT, Dragan Milivojevic <d.milivojevic@...> wrote:
Your computer was compromised, nothing to do with Ebay or Paypal.
On Fri, 1 Sept 2023 at 01:25, Julio VE3FH via groups.io
<ve3fh@...> wrote:
No, I totally disagree with your statement. Based on personal experience, every time I had a credit card compromised it was shortly after either some eBay order or some PayPal payment processing. Last year when I called the bank to report a fraudulent transaction the first thing they asked me was if I had used the card on PayPal adding that several customers reported similar transactions that day with the commonality being PayPal.
I actually I have a second credit card that I use to pay for gas, groceries, etc. and never use online, guess what? that one never got hacked.
I agree with you though that there's no such thing as free shipping, the reality is that S&H is included in the price but no merchant is going to advertise that way, that's just a marketing tactic.
73,Julio VE3FH
On Wednesday, August 30, 2023 at 06:05:16 p.m. EDT, Dragan Milivojevic <d.milivojevic@...> wrote:
You have a million times greater chance of your card details getting
stolen when paying for gas than
the same happening when using PayPal.
On Wed, 30 Aug 2023 at 23:00, Julio VE3FH via i
<ve3fh@...> wrote:
I share your concerns. I bought my TinySA from the SeeSii store in ebay.ca, it and arrived in six days and shipping was USD $2.99, they do carry the NanoVNA H4 and I'll probably buy a NanoVNA from them shortly. The issue with ebay is that payments are processed by paypal so you risk your credit card being compromised, it happened to me at least three times already.
73,Julio VE3FH
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Re: NanoVNA-APP chart options question
On Tue, Sep 5, 2023 at 10:24 AM, Mark KQ4EKK wrote:
Is there a way to select those 5 options in NanoVNA-APP?
|S21|
S21 |Z| shunt
S21 |Z| series
S21 R+jX shunt
S21 R+jX series
NanoVNA app does not calculate/plot S21 impedance measurements. BTW S21 impedance measurements are not very accurate using NanoVNA's because they do not do 12 point error calibration and do not have precise 50 ohm source and termination impedances. You also need a good test jig or stray capacitance will greatly affect the measurements. If you search the archives of this group you will find many discussion posts on this topic. Using a -H4 I have found that i can make fairly good measurements from 2 to 3000 ohms impedance using the s11 shunt method. Roger
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Re: Not available at Ali Express / Zeenko
ae1th@, you mention this is the case with gift cards... I can see that as being a policy. Gift cards, while being great options, they have no real tracking ability especially on the internet. Many scammers out there are stealing money from people with fake IRS or whatever scams and are asking for payment in the form of gift cards. Some unsuspecting people and many of them being people that usually cant afford to lose money, fall for this scams and pay. And then there are the straight credit card frauds or theaves that go to stores and buy gift cards to convert it quickly and then use the gift card or sell the gift cards. Paypal caught onto this and probably made it a policy to not use gift cards. People can also quickly convert the gift cards to bitcoin via paypal payments and then they are clean and completely anonymous when purchasing. So, no more paypal as a gateway.... Price we need to pay for those that are bad out there.
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Nano VNA of a modified 40m hor loop NVIS antenna
How are folks doing on a 40m NVIS antenna for daytime short-range COMS?
A bit more tweaking of my 40m closed LOOP NVIS antenna for 7075 kHz
Less than 1.5:1 SWR across 40m band
Over 50dB return loss at resonant frequency 7075 kHz
The Nano VNA graphs make this loop antenna easy to "tune up"
I'm ready to try it out: 7068 kHz Sunday at 10 AM EDT with THOR 22
This antenna is about 2-3 S-units (15dB) stronger than back-to-back 40m 7 ft Hamsticks
and also a few S-units stronger than my 40m vertical (34 ft lashed to a tree) on daytime coms
de k3eui
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Re: Not available at Ali Express / Zeenko
the problen with visa-ebay-paypal is with ebay-paypal, i can not use any of my birthday visa gift cards on ebay or paypal, visa said - go to a store with an id and use, i have used on the net for cvs-walmare - walgreens with no trouble, it is a problem between ebay and paypal which they wont devulge. fyi
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NanoVNA-APP chart options question
Hello All,
I have attached a pic of the NanoVNA Saver Display Charts options.
Is there a way to select those 5 options in NanoVNA-APP?
|S21|
S21 |Z| shunt
S21 |Z| series
S21 R+jX shunt
S21 R+jX series
NanoVNA Saver 0.6.2 shown
NanoVNA-App v1.1.215 using
Thanks in advance,
Mark
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Re: Not available at Ali Express / Zeenko
No, none of my computers and other devices has been compromised.
I will make no further comments on this pointless exchange because it has veered way off topic for the reflector plus you are dead set on exonerating PayPal and any other "reputable" payment processors of any responsibility.
73,Julio VE3FH
toggle quoted message
Show quoted text
On Thursday, August 31, 2023 at 09:02:22 p.m. EDT, Dragan Milivojevic <d.milivojevic@...> wrote: Your computer was compromised, nothing to do with Ebay or Paypal. On Fri, 1 Sept 2023 at 01:25, Julio VE3FH via groups.io <ve3fh@...> wrote:
? No, I totally disagree with your statement. Based on personal experience, every time I had a credit card compromised it was shortly after either some eBay order or some PayPal payment processing. Last year when I called the bank to report a fraudulent transaction the first thing they asked me was if I had used the card on PayPal adding that several customers reported similar transactions that day with the commonality being PayPal.
I actually I have a second credit card that I use to pay for gas, groceries, etc. and never use online, guess what? that one never got hacked.
I agree with you though that there's no such thing as free shipping, the reality is that S&H is included in the price but no merchant is going to advertise that way, that's just a marketing tactic.
73,Julio VE3FH
? ? On Wednesday, August 30, 2023 at 06:05:16 p.m. EDT, Dragan Milivojevic <d.milivojevic@...> wrote:
? You have a million times greater chance of your card details getting
stolen when paying for gas than
the same happening when using PayPal.
On Wed, 30 Aug 2023 at 23:00, Julio VE3FH via i
<ve3fh@...> wrote:
? I share your concerns. I bought my TinySA from the SeeSii store in ebay.ca, it and arrived in six days and shipping was USD $2.99, they do carry the NanoVNA H4 and I'll probably buy a NanoVNA from them shortly. The issue with ebay is that payments are processed by paypal so you risk your credit card being compromised, it happened to me at least three times already.
73,Julio VE3FH
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On Mon, Sep 4, 2023 at 03:00 PM, Manfred Mornhinweg wrote:
There are basically two ways to use traps in antennas.
A third way that avoids rules of thumb uses an iterative procedure with automatic optimizers to adjust everything for maximum performance: Brian
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A trap is simply a resonant circuit. You can measure it like any resonant circuit. But since traps are build to handle significant power, they are usually somewhat large, which makes them more sensitive to their surroundings. So a trap connected to the NanoVNA will probably measure a little different than its actual behavior when installed in the antenna.
The important curve of a trap is that of its reactance over the frequency range of interest. Traps are usually parallel resonant circuits, so the reactance will start low and inductive at low frequency, increase with frequency, reach a very high value at its resonant frequency, wrap over to a very large value of capacitive reactance, and this capacitive reactance will diminish with further increasing frequency. The important things are what's the resonant frequency, and how steeply the reactances vary with frequency.
There are basically two ways to use traps in antennas. The simpler one is to make the trap resonant in the middle of the higher band, then install it in a position so that the inside leg of the antenna resonates on that band too. The trap acts like an insulator on this band. On the lower band the trap has an inductive reactance, and depending how high it is (which depends on the L/C ratio of the trap), the outer leg needs to have a specific length to make the antenna resonate on that lower band. The total length of the antenna is always shorter than a trapless antenna for the lower band.
This method is easy to understand and tune, but the resonance on the higher band is pretty narrow, and the trap has to stand up against a very high voltage on that band. So another method can be used, that places lower stress on the trap and also results in a better bandwidth: The trap is made to resonate in between the two bands. On the lower band it will still be inductive, so the total antenna length is still shorter than a trapless antenna for that band, but on the higher band this trap is capacitive, electrically shortening the antenna. So the entire antenna works on both bands, the antenna is of a length between that of of trapless antennas for the lower and the higher band, the trap sits in a location where the voltage is moderate on both bands, so it's less lossy and can be smaller, and the trap works on its reactance slopes on both bands, rather than working on the resonance peak on the higher band. This makes the antenna more broadband than in the other case, on the higher band.
So the second method is clearly the better one, but it's a little harder to calculate and tune properly, because the trap's resonant frequency, its L/C ratio, the total antenna length, and the position of the trap, all interact and all have an effect.
One way to do is is to decide the antenna length first. For example for center frequencies of 3.7 and 7.1MHz, 15 meters would be a good length for a quarter wave element with this kind of trap. Then decide the trap position. I would try to put the trap in the middle of the element, or even closer to the feedpoint. Then calculate or measure what inductance you need there to resonate the antenna on 3.7MHz, and what capacitance you need for a 7.1MHz resonance. Then calculate the inductance and capacitance you need in a resonant circuit to get them. The ratio between them will also determine the resonant frequency of the trap. Build the trap, measure it with the NanoVNA , adjust it, then install it in the antenna and either pray or swear, depending on your preference. Then start the usual game of tweaking the antenna until it works fine on both bands.
To do the actual measurent, you don't need to bother with both ports. It's enough to connect the trap to the main port. I suggest that you connect cable pigtails to the NanoVNA, long enough to comfortably reach the ends of the trap, while the trap isn't too close to the NanoVNA. Calibrate the NanoVNA with these pigtails, arranging them roughly in a loop for the short and load tests, and roughly in the positions they will be when connected to the trap, for the open calibration. Then connect the trap and measure the reactance over the desired frequency range, as far away as possible from other stuff, specially conductive one.
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I think this is a good demo:
Ralph¡¯s channel is very informative.
Alex
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Hello
I do it with my NanoVNA but connected to the PC on nanovan-saver. I have a 1 m coxial extension cable (RG223 U) and I calibrate at the end of this cable. I place a small 3 turns coil on a ? 12 mm at the end of the coaxial. I couple this coil as little as possible with the trap and that gives the PJ 19.188 MHz
Then as an attachment
- S11 with the trap in parallel on port 0
- S21 with the trap between port 1 and port 0
The trap is made with 5.5 turns and here is what it corresponds to in Coaxial Trap Desing
The difference between the two types of connections shows a deviation at the resonance of 783 kHz. Each time the trap is placed on a block of expanded polystyrene.
Which frequency to choose? ? ? ?
:(
73
--
F1AMM
Fran?ois
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-----Message d'origine----- De la part de Mike Osborne Envoy¨¦ : lundi 4 septembre 2023 02:14
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Barry K3EUI
Roger Need
Julio VE3FH
