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Rotman Lens

en.wikipedia.org

21–30 of 49 posts

Re: Rotman Lens

#21
post #2

If I understand correctly, is the application of this to quickly switch the direction of sending/receiving? Are there any other applications?

It's a way to create constructive interference in an RF signal in a certain direction (the signal gets stronger in one direction and weaker in others without changing the hardware). It's commonly used in LTE and Wi-Fi as a way to increase SNR directionally for clients.

https://en.wikipedia.org/wiki/Beamforming

Re: Rotman Lens

#22
How difficult it is to get a perfect beam in practice? Can one manufacture a flat rotman lense like that to introduce sinc phase shifts - this should yield a well behaved very directed beam? What are the practical challenges in doing so?

Re: Rotman Lens

#23
post #19

> The principle was first published by Walter Rotman and R. F. Turner in 1963 Astonishing nominative determinism there

Tito Beveridge creator of Tito Vodka, Ed Currie creator of the Carolina Reaper and Pepper X, Keith Weed the president of Britain’s Royal Horticultural Society, Usain Bolt one of the quickest people in the world, Thomas Crapper - commonly but incorrectly attributed with the invention of the modern toilet - founder of Crapper & Co plumbing company, meteorologist Sarah Blizzard, LEO Rob Banks, Donna/Mike/Bobbie Singer all singers with no relation.

I myself have a CTO of a plumbing company in my family from Flushing MI, but that's ever so slightly different.

Re: Rotman Lens

#24
Suppose this is connected to a multiple-output RF transmitter (amplifier), what are the advantages/applications of shifting the phases of the signals passively with a Rotman Lens versus shifting the phases of the signals prior to feeding them to the transmitter (i.e. in the generator)? is the main purpose to compensate for different antennae geometry without having to change the signal generator? I guess things are very different when you can't commute everything into your SDR algorithms.

Re: Rotman Lens

#26

Earlier quoted context omitted.

It does do directional steering. No active array components or physical movement are needed. > If the output ports are connected to individual antennas in an antenna array, this allows shaping the beam in different directions by switching which input port the signal is sent to. From TFA. Presumably the geometrical shape of the lens is dictated by solving for useful phase shifts for different input points. Otherwise y…

>It does do directional steering. No active array components or physical movement are needed. By... plugging and unplugging antenna elements? It makes a fixed directional antenna element array which is configurable to a small degree by choosing which antenna elements to connect and their spatial arrangement. The radiation pattern can only change by physically plugging or moving antenna elements.

> By... plugging and unplugging antenna elements?

No. The antenna elements are always plugged in the same way. By sampling/introducing the signal at a different physical position on the lens (or multiple positions simultaneously), you create different physical distances and phase shifts for each element, and therefore a different beam direction.

...Apropos of nothing, this reminds me that a long ago, I played on a Minecraft server where one of the boys made a piston display with controlled by a pressure plate array. I was shocked by how he managed to transmit the signal with a simple wire. Maybe it was a similar idea, using the propagation distance...

Re: Rotman Lens

#27
post #19

> The principle was first published by Walter Rotman and R. F. Turner in 1963 Astonishing nominative determinism there

Tito Beveridge creator of Tito Vodka, Ed Currie creator of the Carolina Reaper and Pepper X, Keith Weed the president of Britain’s Royal Horticultural Society, Usain Bolt one of the quickest people in the world, Thomas Crapper - commonly but incorrectly attributed with the invention of the modern toilet - founder of Crapper & Co plumbing company, meteorologist Sarah Blizzard, LEO Rob Banks, Donna/Mike/Bobbie Singer a…

These are called aptonyms: https://en.wikipedia.org/wiki/Aptronym?useskin=vector

Re: Rotman Lens

#28

Earlier quoted context omitted.

>It does do directional steering. No active array components or physical movement are needed. By... plugging and unplugging antenna elements? It makes a fixed directional antenna element array which is configurable to a small degree by choosing which antenna elements to connect and their spatial arrangement. The radiation pattern can only change by physically plugging or moving antenna elements.

> By... plugging and unplugging antenna elements? No. The antenna elements are always plugged in the same way. By sampling/introducing the signal at a different physical position on the lens (or multiple positions simultaneously), you create different physical distances and phase shifts for each element, and therefore a different beam direction. ...Apropos of nothing, this reminds me that a long ago, I played on a Mi…

>By sampling/introducing the signal at a different physical position on the lens

Which is accomplished with active components (or multiple frontends). The word "active" is carrying a lot of weight in what isn't actually that important of a distinction

Re: Rotman Lens

#30
post #27

Earlier quoted context omitted.

Tito Beveridge creator of Tito Vodka, Ed Currie creator of the Carolina Reaper and Pepper X, Keith Weed the president of Britain’s Royal Horticultural Society, Usain Bolt one of the quickest people in the world, Thomas Crapper - commonly but incorrectly attributed with the invention of the modern toilet - founder of Crapper & Co plumbing company, meteorologist Sarah Blizzard, LEO Rob Banks, Donna/Mike/Bobbie Singer a…

These are called aptonyms: https://en.wikipedia.org/wiki/Aptronym?useskin=vector

or nominative determinism
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