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About eco32

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    Advanced Member
  1. Vivaldi in progres, Im waiting for bigger drill I do not know completely what the result will be, I make from garbage.
  2. conclusion from simulations and from experiment: shape is ok, gemetry is wrong! Why? The ratio of focal length to aperture size (ie., f/D) known as “f over D ratio” is an important parameter of parabolic reflector. Its value varies from 0.25 to 0.50. calculator: https://satlex.de/en/fdratio-params.html?diam=90&depth=15 in my case is f/D = 0.16 => Geometry is wrong - may it be that with other type of feed will be more profitable. Any parabolic antenna larger than 120cm is horrendously expensive, building big grid antennas is reasonable. Example from Czech Republic: https://www.ok2kkw.com/wsjt2006/23cm2008.htm also for Earth–Moon–Earth communication (EME). Grid vs double grid with siple dipole fed without small reflector as case above 13.5dBi VS 17dBi I DID IT, AND YOU DONT HAVE TO!
  3. how to finf focal point: you point the antenna towards the sun, and sliding cheet of paper (I couldn't find a better source to ilustrate) LASER use:
  4. It was concept picture, it has one focal point
  5. This requires an explanation as to why you think it is stupid. Of course not, such a grid reflector is best for dipole feed that have parabolas smaller than 10xlambda BTW, it is prototypingc, parabolic offset will be consider in other project. Here we consider the "siple dipole" feed and exploration, what we can do. @Admin do you agree with me?
  6. Measured very roughly, when the dimensions of the system are accurately measured the results will be different Thats the basic grid - 17.3 dBi That's double grid: 19.8dBi option B - it does not work: 16.9dBi conclusion: doubling the reflector area gives ~~~~ 2.5dBi or more of the gain. I will show real pictures later, will be mechanically difficult. I think I can get a few dB more by improving the feed.
  7. That's what my fellow senior radio amateurs tell to me
  8. I have two same grids, lets fin out how it will be in thi combination (simple ilustration): (simulation without optymalization shows inceasing gain from 17.2dBi to 19.6dBi)
  9. @Admin has right @anoduck: You can use siple laser pointer to findout where your beam is radiating. focus point can be checked by peaper sheet and sun focus point can be checked by peaper sheet and sun. BTW: The sun generates a lot of noise and pointing the anena at the sun You can also adjust the focal point.
  10. I have acces only to "A Novel Wideband Quasi-Yagi Antenna for Base-station Applications", the is no dimensions. From charts it looks like this is antenna for a ~2.3GHz and ~3.3GHz
  11. from documents:"Wideband quasi‐Yagi antenna with stable radiation patterns for base‐station applications" and "A Novel Wideband Quasi-Yagi Antenna for Base-station Applications" > simulated gain ranges from 8.0 dBi to 9.8 dBi in the operating band. that is same gain as in simple biquad but a simpler design.
  12. Is there a director shape that works best, a square, a loop, a simple rectangle , (...)?
  13. In my understanding of MIMO, these antennas transmit separate signals, +45 and -45degr, in the simulation should be considered separately and not together. Gain will be 6dBi, not 9dBi.
  14. Prototyping ongoing
  15. Design with slot or with coaxial splited balun - the reflector disc is smaller than the previous design, I guess that's the reason for the lower gain.