Microwave:

• Line sight but not a perfect theoretical laser-like precision. Transmitter energy is beamed in a narrow cone. Any receiver positioned in the cone will be capable of overhearing the transmission.
• Advantage is that microwave links can be very high bandwidth and thus are usually multiplexed and difficult to sort out communications.
• Single point to single point link makes transparent encryption rather easy and an inexpensive way to defeat eavesdropping.