focus defocus modefocusingfocusing anodefocusing coilfocusing electrodefocusing gridfocusing magnetfoilfoil patternfoldback current limitingfolded dipole antennafolded hornfoldingfootfoot candlefootprintforawrd looking infraed unitforbiddenforbidden bandforbidden gapforbidden regionforceforce balanceforce balance tranducerforce current analogyforce fieldforce functionforce of alignmentforce of attractionforce of gravityforce of inertiaforce of interactionforce potentialforce stickforce vectorforce voltage analogyforcedforced responseforcingforcing frequencyforcing functionforcing responseforeground colorforeground processingforeignforeign atomforeign matterforeign particleforeign substanceforeshortened
