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Comment by colechristensen | Hacker News Reader

No, this is to concentrate the radio waves into a desired shape. Stronger in this direction, weaker than that.

Think of it very vaguely like a parabolic mirror on a flashlight directing the light vs a naked light bulb putting light out in all directions. (this is a bad metaphor for what's going on but it's the basic idea of the goal)

To change the direction you have to physically move the antenna OR have an active phased array antenna with an electronic component which has a variable phase change to be able to move the beam around while leaving the antenna fixed.

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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 you could just use a bunch of delay lines.

I wonder if anybody's ever designed a 3D version of this. You might get a wider range of inputs, or more precise steering, by shaping the delays on a non-Euclidean (curved) surface (like a sphere or a saddle).

>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.

It can be changed electronically and is commonly used that way in LTE and Wi-Fi implementations of Beamforming.

> 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...

>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

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