new active antenna with bootstrapping of the SFET to minimize the input capacitance

Am 27.12.2020 um 23:29 schrieb snipped-for-privacy@highlandsniptechnology.com:

good bye John Larkin - I recommend a university to you

Yes, you are likely corrent, but it appears to be the best we will have in English. (I know some German, but still...)

Joe Gwinn

Am 27.12.2020 um 23:26 schrieb snipped-for-privacy@highlandsniptechnology.com:

The radials ensure that the full dBi is available at small elevation angles. Without radials you have zeros at small elevation angles (if there is no metal background).

That with the e-filed You wrote is really balderdash.

bye

Am 27.12.2020 um 23:42 schrieb Leo Baumann:

with radials:

So you don't think a properly-terminated transmission line looks like a Z0 resistor on the input end? What _does_ it look like, then, in your view?

Inquiring minds want to know. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

Am 28.12.2020 um 00:49 schrieb Phil Hobbs:

I'm looking forward the new Larkin-Chart instead of the Smith-Chart.

Yes, of course, a properly-terminated line looks like a Z0 resistor on the input end.

But a non-properly source impedance causes a wrong matching at the end of the line, because the non-properly source impedance will be transformed to the end of the line.

Every Smith-Chart tells that to You. The other possibility is to calculate it:

beta=2*PI/(c/f) Zout=(Zin*cos(beta*l)+I*ZL*sin(beta*l))/(I*ZIn/ZL*sin(bet*l)+cos(bet*l))

regards

Oh, I have a BSEE already. I recommend Spice to you.

One way to make a super wideband high-power 50 ohm dummy load is just a long spool of coax.

--

John Larkin      Highland Technology, Inc 

The best designs are necessarily accidental.

e

He is mocking you suggesting that the noise level can be reduced by attenua ting the signal along with the noise.

This is the guy who demeans others for being "nasty", a term he picked up f rom Trump, his idol. He is also the guy who continually complains that the re is too much off topic discussion and not enough technical discussion, th en nips at the ankles of someone posting on topic.

I like the circuit. It shows a high degree of rational thought.

--

Rick C. 

- Get 1,000 miles of free Supercharging 
- Tesla referral code - https://ts.la/richard11209

Then this guy shows just how little he knows by assuming the termination resistor in the simulation is intended to be part of the circuit.

You are being nastier than usual. Do you have something against other people being able to design something you can't?

--

Rick C. 

-- Get 1,000 miles of free Supercharging 
-- Tesla referral code - https://ts.la/richard11209

After powering up the 8970B, connect the noise head to the RF input and let it warm up for at least 30 minutes. Push these buttons:

- START 432

- STOP 432

(There is a FIXED FREQUENCY button as well, but for some reason it insists on continuing to do a swept calibration if you use that. Just set the star t and stop frequencies to the same frequency instead.)

- INCREASE smoothing to x32 or x64 for best results, since you're measuring at only one frequency and don't care about speed

- Wait for the first reading to appear, then hit CALIBRATE (twice)

After calibration finishes, insert your device between the noise head and R F input. It should read the NF and gain after a short delay, depending on the smoothing level.

The above assumes your source's ENR table has been entered and that the 897

0B's IF gain has been calibrated. If not, you'll get an error code, and wi ll need to go through one or both procedures. I don't recall the exact ste ps involved but I remember finding them reasonably well-documented in the m anual.

If you need to calibrate the IF gain, I believe you'll need a 346B or 346C head. (If you changed the lithium battery, you'll need to do both.) Other wise any of the 346A/B/C heads would probably be OK. For everything I've e ver done with mine, I've used a 346C. It's easier to use an outboard atten uator with a 346B or 346C if necessary, than it is to use an outboard ampli fier with a 346A.

Also note that you won't usually see a zero NF after calibration because ex tremely small gain errors have an outsized effect near 0 dB NF in the Y-fac tor math. Not a concern in most normal use cases.

-- john, KE5FX

thanks

I just thought it may be interesting for You in USA, because we Krauts have a complete theory for active antennas.

I tried to translate it for You, but with the formulas and the pictures the translation didn't work well.

I don't want to get involved in politics, but all of Europe was offended by Trump.

regards

s

the

enuating the signal along with the noise.

up from Trump, his idol. He is also the guy who continually complains that there is too much off topic discussion and not enough technical discussion, then nips at the ankles of someone posting on topic.

If you don't want to talk politics, you came to the wrong place. Notice th ere are at least three totally separate discussions going on in this thread . Whenever I mention nuclear energy I get criticized, but hijacking a thre ad to discuss it is ok.

Anyway, AMD is interested in antennas and such. He does a lot of experimen ting, but is not so big on theory. He comes up with some interesting discu ssions though.

Larkin is just here to be an ass. I really can't believe he thinks the 50 ohm resistor on the output of your spice circuit is intended to be part of the amplifier rather than being the load. I guess you should have labeled it Rload for him.

--

Rick C. 

-+ Get 1,000 miles of free Supercharging 
-+ Tesla referral code - https://ts.la/richard11209

Open the original DF file in one window, Open the Google Translated page in an other window.

When in the translated text there is a reference to a formula or figure, simply look at the original PDF window. Use page, chapter or figure numbers (Bild) to synchronize the two documents.

Sure if the radials are at least a 1/4 wavelengths long. The question is, what is the point of having a short monopole, if you still would need huge radials. ?

Loading coils in the radials to extend them electrically ?

Thanks to you for spreading the idea of using bootstrapping to cancel input capacitance.

Sure, we all know about the impedance-transforming effect of transmission lines. It's due to the phase delays in the reflected waves.

However, if there's no reflection at the far end, there's none at the other.

A good many of us series-terminate line drivers and other output devices, because in a point-to-point link that avoids artifacts from reflections: it works just the same into an open-circuit load as into a properly-matched one, except with twice the signal amplitude (and a good deal lower power dissipation in many cases).

Transmitters are the same way, except backwards: you want a good match at the antenna end but not at the transmitter, because otherwise you'll waste half of your available power.

(Hint: the closed-loop output impedance of an op amp circuit might be 10 milliohms in some frequency range, but you sure won't get maximum power by attaching a 10-milliohm load.)

Cheers

Phil Hobbs

Am 28.12.2020 um 11:51 schrieb Phil Hobbs:

The discussion about R9 in the circuit is trivial. To change it to 1 MOhm like John Larkin said is balderdash. Of course we need matching at the input of the coax-cable.

As I see John wants to provokate - I hate this non-science behavior.

Subject was active antenna and reduce input capacitance by bootstrapping.

regards

You know, we haven't had a realio, trulio crazy German since Helmut Wabnig hung it up a few years ago. (Gerhard and Joerg are too sane for the job.) Back in the palmy days we had plenty of them--nice to have a reminder. ;)

Cheers

Phil Hobbs

Yup, a real live crazy German. Welcome!

Cheers

Phil Hobbs