I was planning on using a mobile 2/440 antenna either w/a mag mount or
thru hole on some sheet metal , on my roof .


naturally unlike in a car the coax run will be rather longer than is
typically used in a car , i presume therefore this might change to the
point where using this set up might be 'useless'??


are they particularly sensitive to say impedance changes or such?


100ft run of lmr400 or 1/2'' heliax will be used

thanks