You would need very expensive jammers to be effective against drones. The power needed to jam every direction in the sky increases exponentially by distance.
Jamming would never really be a viable solution in a city except during an actual attack. It would cause more damage then it could ever hope to prevent. It would have to block the radios and GPS used by planes, helicopters, police, firefighters, and anything else remotely near the jammer, to actually be effective at blocking a radio controlled drone.
Nonsense. Get directional GPS antennas and point them straight up into the sky and surround the whitehouse. While you're at it point some EMP guns straight up in the air too. Nothing is suppose to be flying over the whitehouse so you don't have to worry about disrupting civilian planes, etc... Making them powerful enough to go a few thousand feet straight up but not powerful enough to interfere with LEO satelites would be simple. If you used a directional antenna (again pointed straight up and surrounding the whitehouse) to block all signals then the only drones you would have to worry about would be ones that navigated via visual cues which would be considerably harder to do.