High speed battlefield communications benefit from having a secure channel. Encryption works, but a secure cable would work wonders and give even greater security. Of course, it is hard to lay a cable across a large distance during war, and it wouldn’t stay with a group as they wander through a battlefield. However, suppose operators at both ends were to shine fairly high power laser beams up into roughly the same area of sky and scan them round. A high power laser ionises the air as it travels through. As the two beams (one from each side) cross each other, an electrical circuit would be formed from end to end – effectively a cable. The link could be deliberately broken and re-established according to a time schedule to add security.
I can immediately see a few problems but problems aren’t always fatal. First, there exist such things as laser seeking missiles. Secondly, I am not sure whether the beam would radiate the signals so the transmissions might be easily intercepted, making it no better than a secure radio channel. Needs work but shows potential.