[bostik]

> Why aren't HFT firms using short wave radio (DXing)?

They are. See mshook's response, with nice reference links downthread: https://news.ycombinator.com/item?id=16196339

[mkj]

Those are microwave which basically need line of sight? I was thinking of lower frequencies which can sometimes go hundreds of kilometers without repeaters.

[jlgaddis]

Bandiwdth, mostly.

The lower you go in frequency, the less bandwidth is available.

The entire "HF" spectrum is ~30 MHz. My Wi-Fi at home uses a wider channel than that.

The lower frequencies -- that will travel across the ocean, unaided -- don't have anywhere near the bandwidth necessary (to support the throughput that they need).

[Retric]

You want your severs as close as possible to an exchange. Even 2 miles is a noticeable increase in latency.