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0 pointsColinWright2y ago0 comments

Radars work in the 3cm or 10cm ranges[0], so you'll always get a return from the towers and the blades, and that significantly reduces the energy that gets beyond the turbine to illuminate potential targets.

Reflections from targets also need to pass the turbine(s), reducing the return even more.

Beamwidths are significant, depending on the antenna configuration. You can have beamwidths of 0.5 degrees and more. That helps detection, but reduces target discrimination. It helps get the energy past the turbines, but you tend to have "wound down" the power output to allow for that. So it doesn't really help.[1]

You know where the turbines are ... knowing the exact positions of the blades won't help at the frequencies being used.

In short, it's complicated. Radar pulses are like HUGE lumps of energy flying through space, and delicate things like turbine blades chop them up and defect them around, preventing them from getting to, and then from, the targets.

[0] Marine radars, X-Band and S-Band. There are other ranges and bands.

[1] Yes, this is all extremely simplified and inaccurate, but I'm trying to give a sense of what's going on.

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swores2y ago· 2 in thread

Thanks! I wouldn't have guessed the sizes were so large for radar, and just assumed that in current era radar would have progressed to the point of even being able to not send pings at the rotating blades in sync with their rotations (ie always firing radar somewhere within the circle but only at the spots where the blades are not) the same way machine guns fired past propellers on WW2 (or WW1?) fighter planes figured out. But of course a bullet and a radar setup isn't at all the same thing.

ColinWrightOP2y ago

The details I give are for marine radar, where off-shore wind-farms are a significant issue. But radar in general works on similar wavelengths, and a lot of clever processing can be done to "improve" the images you get back, especially when you have a lot of images that can be combined, rather than sweeping the radar around and only get 20 to 120 sweeps per minute.

There are trade-offs between how often you can ping versus how far you want to see versus how much energy you can send out versus how big the "lumps" are, etc. The sums/calculations are pretty simple, but not obvious until you've seen them, and then they are.

But if you want to see something at 32NM ~ 60km, you have to send out a lot of energy, so the "lumps" need to be pretty big, especially as the returns drop off as a fourth power with distance.

swores2y ago

Any idea to what extent the problems can or can't be solved by money vs. a limit on maximum quality of radar before needing to break the laws of physics to improve further?

E.g. are the US military saying "yep those are the issues we face too" or "haha our tech has more than enough energy to get around all these problems"?

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