Effectively, there is no theoretical limit to the applicability of {TAIL ~ the invention}, although practical difficulties may occur at extremes of {HEAD ~ low and high frequency} 
Effectively , there is no theoretical limit to the applicability of { TAIL ~ the invention } , although practical difficulties may occur at extremes of { HEAD ~ low and high frequency }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD