I meant to write about this electronic warfare topic for a long time, but now I suppose it's jsut as fine to just push readers towards looking it up:
Imagine a late 80's scenario for example: An armoured battalion battlegroup advances along a road in a South German landscape (woodland hills left and right, with only unpaved forestry roads - and a paved road in the valley where there are also buildings between the agricultural areas). The defenders activate several radio jammers near the company-sized vanguard and a tank platoon lying in a flanking ambush opens fire. Valuable seconds of return fire lag are gained and doom the vanguard.
The effect would have been complimentary in a similar way as the combination of HE/DPICM and scattered mines would be; the targets would be very much restricted in their ability to cope with the challenge.
Another example: An infantry platoon is meant to raid a picket and take prisoners and radio sets for intel. A few expendable jammers are used to isolate the picket and to keep it from calling for help.
Even some experienced and longtime-serving officers don't happen to know about this and EW is in general still a black box to many. This may be part of the reason for the excessive reliance on radio comm and electronics these days.
So here are a few links, just in case you're interested in peeking at the stuff a bit:
About the hand-emplaced HEXJAM
Russian 3RB30 (couldn't find worse link, obviously)
About artillery-delivered SAMEL 90, Bulgarian version of Russian 2RB30
Electronic warfare in general:
For German, Austrian and Swiss readers:
(Band 17A; boring, but acceptable)