Advantage: speed limit about 0.997c. Easy to get straight communication lines.
Disadvantage: weather dependent (?), hard to cross Transatlantic ocean (but far from impossible).
2015 The Times UK: High speed traders make millions in split seconds
2015 Bloomberg: Speed Traders Team Up in Microwave-Tower Superhighway Plan
2015 McKay Brothers Microwave Sets New Latency Record Between UK and Frankfurt
``McKay Brothers microwave lowered latency to 4.192 milliseconds on its wireless route between Frankfurt and Basildon. "
2014 McKay Brothers, a Geneva-based network provider for trading firms, is opening a microwave data link between the UK and Germany
2014 HFT In my Backyard
2014 Innovator Windy Apple Announces Transatlantic Plans and Offers Promotional Pricing for New York-to-Chicago Microwave Network
2014 Bloomberg: High-Frequency Traders Find Microwaves Suit Their Need for Speed
2014 Bloomberg: Wall Street Buys NATO Microwave Towers in Quest for Speed
2014 Banking technology: Perseus Telecom launches ‘trans-Atlantic’ microwave service
2013 Some HFT Firms May Have Overcooked Their Microwave Strategies