Abstract
Vertical surface
protection in a security installation is achieved by detecting
disturbances in a Unique Band X microwave beam sent from transmitter
to a receiver. The transmitter and receiver have associated
beam aerial's of extended horizontal aperture of not less
than 0.50 meters to mitigate the effects of surface reflection
from metal scaffold, plastic sheeting or netting, wooden boarding,
brick or stone facing. The aerial's are preferably slotted
waveguide arrays and the advantages of using circular polarization
are shown. Circularly-polarised slotted waveguides arrays
are disclosed having a centre feed to minimize frequency dependent
beam spreading....
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