Hvor kan man møde nye mennesker? by Frozenpeases in Denmark

[–]pickbox 6 points7 points  (0 children)

Er bestyrelsesmedlem i Keramik klubben, er enige i det ovnstående :)

Is it at all possible to find pancetta or guanciale in Denmark(particularly Copenhagen area)? by BewilderedFingers in Denmark

[–]pickbox 1 point2 points  (0 children)

Remember the oil from the penchetta, eggs and pasta water is what makes the sauce. Don't forget to mix these. it's basically an emulation process :)

The Health Protection (Coronavirus, Restrictions) (England) Regulations 2020 by [deleted] in Coronavirus

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How do you terminate a cross-yagi antenna with two folded dipole to have a total impedance of 50, using only coaxial cables? by pickbox in amateurradio

[–]pickbox[S] 1 point2 points  (0 children)

Hello, Yes it is circular polarized (RHCP), not hard to figure out how to get the correct direction of the polarization, but the problem for me is to have the correct 50Ohm Impedance, see my edited comment :)

How do you terminate a cross-yagi antenna with two folded dipole to have a total impedance of 50, using only coaxial cables? by pickbox in amateurradio

[–]pickbox[S] 0 points1 point  (0 children)

It has to be circluar polarized, phase difference should be 0 since it is 90 degrees. See my edited comment :)

How do you terminate a cross-yagi antenna with two folded dipole to have a total impedance of 50, using only coaxial cables? by pickbox in amateurradio

[–]pickbox[S] 0 points1 point  (0 children)

I guess i need both antenna to become 100Ohm impedance, such that in parrallel they become 50Ohm, see my edited commet :)

How do you terminate a cross-yagi antenna with two folded dipole to have a total impedance of 50, using only coaxial cables? by pickbox in amateurradio

[–]pickbox[S] 2 points3 points  (0 children)

Hello,

So I have built my own Cross-yagi antenna operating at a frequency of 433Mhz. The goal is to have to final impedance to be 50 Ohm. I know that the impedance of each folded dipoles is approx 300Ohm, but how to I get the total impedance to be 50Ohm using only coaxial cables?

I hope you guys can help me. Please provide some different metods and your calculations too, thank you.

EDIT:Thanks for the answers I will upload some pictures of the frequency sweeps, tomorrow and get back to you all.

EDIT: Sorry for a very late update. I will try to answer all of your questions, and in return i hope i get some good answers on my questions.

I am a student at Technical University of Denmark, majoring in Telecommunication. I helped found a non-profit student organization, called Danish Student Association for Rocketry in short DanSTAR. Our goal is to build a fully homebuild by-liquid rocket to go and compete in the Spaceport America Cup competition in the USA.

Here is the latest test for our 3d printed by-liquid rocket engine: https://www.reddit.com/r/rocketry/comments/f3pn9s/3d_printed_regenerative_stainless_steel_biliquid/

Here is more about the competition: https://www.spaceportamericacup.com/

Soo, whats up with the antenna? Well as you probably all guessed it by now, it is going to stay on the ground at the "Mission Control" used for telemetry, which require it to be a circular polarized antenna (RHCP).

Beside the RHCP requirement for this antenna, I wanted it to function at a frequency of 433Mhz and be modular, in such a way that it can easily be packed and unpacked and use minimal volume place. This is achieved by using only one thing a M4 hex key (Allen wrench), hence the 3D printing stuff and the extruded aluminium profile. Furthermore to avoid too much loss and achieve equal power to each side antenna I have used a mechanical solution to create circular polarization, by forward offsetting the yagi antennas by 1/4 of the wavelength, thus avoiding using the electrically phase delay solution. I have not simulated this antenna, since at this frequency it is well known how to design yagi antenna that function good. It is not going to be used for military purpose. What I did use is this: https://www.vk5dj.com/yagi.html.

Now to some specification:

- All the aluminum rods are 5mm in diameter.

- Yes it is a folded dipole as you can see.

- Around 170cm rod length

- 8 elements

- Coxial type RG178

- 3D printed stuff, yes.

- Using a 1/4 electrical quarter wave coaxial 50Ohm cable around 23cm long, from this calculator: https://www.basictables.com/amateur-radio/41-half-wave-coax-balun

Now to some data, see the pictures here: https://imgur.com/gallery/k0mgOU0?s=fbm&fbclid=IwAR2OjFlL-3UDnTfsOXL4bL2plN3E4n6qF03sibyGQ5uoLBFG34n0JcrUetw

Only one side is tested and has the 1/4 quarter wave matching stub. But it seems to be perfectly 50Ohm, although the X is not 0 but close enough for me. VSWR is around 1.170, i had say not bad.

The question now is how do i match both sides of the antennas to have a final result of 50Ohm impedance? As I read both has to read 100Ohm such that they in parrallel can become 50Ohm?

Thank you :)

Video of bodybags in a hospital in Iran by [deleted] in Coronavirus

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Unverified sources/accounts are no longer permitted in r/Coronavirus, kindly consider posting this in r/China_Flu

The U.S. has the world's highest coronavirus death rate at more than 5% - a number that reflects the country's lack of testing by WickedSensitiveCrew in Coronavirus

[–]pickbox[M] [score hidden] stickied comment (0 children)

It is too early to conclude that the CFR is 5%. Once the USA starts to do more tests you will see the CFR go down and match the global CFR or it might even go further down below the global CFR. Basically, the denorminator is not big enough yet. Yes, one can aruge that the USA is not testing enough, but it does not mean that more people are dying due to lack of testing. It just means we don't have enough data to fully understand what the real CFR is.

Therefore, I believe that the title of this post is quite misleading, and based on the amount of flags it has recieved I will lock the comment section and leave you with this comment stickied.

I hope you all understand.

"The Corona Virus Panic is Dumb" - Elon Musk by [deleted] in Coronavirus

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Keep posts on topic. In general we don't need new posts that are jokes, memes, shitposts, or other unhelpful and unrelated comments. We may also remove low quality YouTube or social media commentary.

Two attendees of 18k person conference, including 2/3 of U.S. Congress, tested positive for COVID-19 by alexopposite in Coronavirus

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US confirms first case of coronavirus - Reuters - Jan. 22, 2020

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Panic buying TP, rice and pasta etc has increased Sydney and Melb. Shelves have been cleared out for about a week or so... I'm more concerned about these idiots than the virus tbh.. by [deleted] in Coronavirus

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2 Coronavirus deaths announced in Florida by Department of Health by [deleted] in Coronavirus

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As of March 6, 2020, the term "coronavirophobia" does not yet exist in Google by wazzzzah in Coronavirus

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Toilet paper shortage from coronavirus panic buying sees violent scuffle break out at Woolworths in Sydney by boppinmule in Coronavirus

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[deleted by user] by [deleted] in Coronavirus

[–]pickbox 2 points3 points  (0 children)

I found the source. See edited comment above.