Added: 3 years ago
From: mittechtv
Views: 33,250
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  • Seems like a lot of trouble just to turn on a light bulb.

  • is it possible to buy such RF transmitter?

  • Don't know much here! (1) Will the dipole work setup in vertical with radiator on top? (2) Say becoming omni better signal to vertical receiving antennas? (3) In vertical how much gain is lost or does the 1/2 wave dipole have any gain? Anyone help? Thanks.

  • Is anyone familiar with the wi-tricity work funded by Microsoft? It was using tesla type pancake coils, claimed to be very efficient. With a 360 degree vector, could something like this go o.u.?

  • It is just a polarization loss factor (PLF) that you are seeing. It is equivalent to spraying a beam of water horizontally through a vertical opening. Almost no water goes through. But in this case, the dot product of two perpendicular beams would be exactly 0. So, at normal incidence, there is no transmission,

  • Cross Polarization causes ~20db decrease in siganl strength hence the dimming of the lightbulb.

  • question whydoesnt it transmit when perpendicular?

  • It is transmitting all the time. The dipole antenna radiates in a specific pattern which when the bulb's antenna is aligned to allows the bulb to be energized.

  • okay thank you i'm doind a teach the class project and needed to know

  • cannot that thing conduct a volatage in our body? I mean we might have some kind of a rod in our body as well.

  • @goodluckpeace44 Radio frequencies are (usually) absorbed by water and dissipated. It would take a LOT of radio energy to have an affect on the human body. One case is in the far northern bases with microwave transmitters, some of the crew, when they get cold, step in front of the dish for a fraction of a second to "warm up". Stay too long and their eyes would boil -_-

    It's part of the reason satellite dishes lose connection in heavy rain and why radio signals don't travel well through trees.

  • i think there is a cos(theta) function involved somehow, which is like an attenuation of the signal. basically, the current picked up in the recieving antenna/lightbulb is a dot product of its direction and the direction of the electric field: max when aligned, zero when perpendicular - that's because cos(theta) is 1 at theta=0 and 0 at theta=90 degrees

  • @fuqueue i like greek

  • poor tesla, they couldnt even put your name in the tags lol. hey if anyone wants to learn about teslas wireless transmission of electicity on the earth and interplanetart energy transfer just come over to my site, if you love tesla and radio you will love my videos! thanks poor tesla,

  • He did some amazing things.

  • he's just demonstrating polarization. It's pretty neat, although with that much power (probably a few hundred watts) I wouldn't want to be standing there.

    You lose something like 20 db for cross polarization, so when the antennas are the same polarization, the bulb is brightest.

  • how is this done. holy mackeral - can some one explain to me?

  • Hmmmm.... Great Demo of the dipole ant.

    John

  • hehehehehehehehehehe

  • Tesla did this about 100 years ago, big deal. Now it takes MIT kids with current technology to do this? When did science become like a religion and rigidly opposed to new ideas?

  • Sorry, but you have to learn the basics before getting into the big stuff. Experiments like these, while done before, are the foundation of the "current" technology you speak of.

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