[jjk166]

> Ground radar is line-of-sight. The Earth is round. Anything below the horizon is invisible.

That's not true. Ground based radar can see over the horizon (hence the term Over-the-horizon radar) by taking advantage of the refractive index of air, allowing the radar waves to essentially curve along, as well as by bouncing radar waves off the ionosphere.

Given that this is the foundation of TFA's argument, it does not instill confidence.

https://en.wikipedia.org/wiki/Over-the-horizon_radar

[adrian_b]

Over-the-horizon radars have very poor resolution, so they are useful only for early warning, not for guiding an interceptor.

For targeting at distance, you need antennas mounted on high masts or airborne radars.

[jjk166]

You don't need to target at distance, you are limited by the range of your interceptor. OTH tells you which interceptor battery needs to be looking where.

[echoangle]

On the other hand, those only really tell you that something is coming somewhere in that direction, OTH radars don't have the resolution for targeting afaik.

[jjk166]

Knowing that it's coming and the general direction is what you need for command and control, the actual interceptor is going to be much more limited in range than the targeting radar.

[protortyp]

Exactly. In an earlier draft I went deeper into this, but cut that section among others for brevity.

[protortyp]

I cut this on purpose due to the poor resolution other commenters have mentioned already.

[jjk166]

You shouldn't have because the poor resolution is irrelevant and OTH radar is widely used in BMD systems.