▁They ▁are ▁often ▁found ▁in ▁standard ▁desktop ▁mic row ave ▁sources ▁used ▁for ▁research ▁purposes . ▁▁ ▁A ▁slot ▁anten na ' s ▁main ▁advantages ▁are ▁its ▁size , ▁design ▁simplicity , ▁and ▁convenient ▁adaptation ▁to ▁mass ▁production ▁using ▁either ▁wave guide ▁or ▁PC ▁board ▁technology . ▁ ▁Str ucture ▁An ▁anten na ▁consisting ▁of ▁multiple ▁parallel ▁sl ots ▁in ▁a ▁wave guide ▁is ▁a ▁widely ▁used ▁array ▁anten na ▁which ▁radi ates ▁a ▁narrow ▁fan - sh aped ▁beam ▁of ▁mic row aves ▁at ▁right ▁angles ▁to ▁the ▁wave guide , ▁with ▁its ▁narrow ▁axis ▁in ▁the ▁plane ▁of ▁the ▁wave guide ▁and ▁its ▁wide ▁axis ▁per pend icular ▁to ▁the ▁wave guide . ▁▁ ▁Multiple ▁slot ▁versions ▁are ▁widely ▁used ▁in ▁rad ar ▁anten nas , ▁particularly ▁marine ▁rad ar ▁anten nas ▁on ▁ships , ▁and ▁for ▁the ▁sector ▁anten nas ▁used ▁for ▁cell ▁phone ▁base ▁stations . ▁ ▁Due ▁to ▁Bab inet ' s ▁principle ▁a ▁slot ▁in ▁a ▁wave guide ▁has ▁the ▁same ▁radiation ▁pattern ▁as ▁a ▁driven ▁rod ▁anten na ▁whose ▁rod ▁is ▁the ▁same ▁shape ▁as ▁the ▁slot . ▁This ▁can ▁be ▁used ▁to ▁determine ▁the ▁radiation ▁pattern ▁using ▁calculations ▁for ▁a ▁more ▁conventional ▁anten na . ▁ ▁Usually ▁a ▁sl otted ▁wave guide ▁anten na ▁is ▁protected ▁by ▁mic row ave ▁transparent ▁material , ▁which ▁may ▁vis ually ▁obsc ure ▁the ▁sl ots . ▁ ▁Nevertheless , ▁it ▁is ▁easily ▁distinguished ▁from ▁a ▁par abol ic ▁reflect or ▁by ▁its ▁flat ▁or ▁t ube ▁shape .