In a sense I'd say it is on the lower end because i'd say the lowest achievable frequency is that which originates from the blackbody radiation at absolute zero. As for the upper limit I see no reason why there should be a limit.
Can electromagnetic energy be pushed into a home as a weapon? Like a bolt of electricity using a linear amplifier. Would it be similiar to the ADT or ADS weapon systems used by law enforcement or the military? I've been attacked with something here in Long Beach, Ca and its a shockwave with electricity.