Frequency hopping can only help if there's frequency to hop to, and I'd imagine a military jammer would angrily spew as wide a band of noise it can to ensure ev

Frequency hopping can only help if there's frequency to hop to, and I'd imagine a military jammer would angrily spew as wide a band of noise it can to ensure everything is jammed. A tank with an omnidirectional antenna jamming -30dB (or more because it's not like FCC/similar regulations apply to the military in a war zone) would have a pretty decent RF bubble around it.