Manual

©1999 Navia Aviation AS 21464-5 Antenna
USER MANUALNORMARC 7050
MARKER BEACON
6-15
6 Antenna
Normarc supplies single and dual antennas, NM 3561 and NM 3562 respectively. The single
antenna may be used for inner, middle and outer marker, while the dual antenna is specially
designed for outer markers. The advantage of the dual antenna is a lower spread in
FLYING
THROUGH TIME inside the localizer coverage area. In addition to two antenna elements, the
monitor and distribution network DI 726 is included in NM 3562.
Figure 6-1 Antenna block diagram
Figure6-2 shows the field strength of the radiated signal directly above the middle marker
antenna. Figure6-3 and Figure6-4 illustrate the field strength above the outer marker
antenna, using single and dual antenna, respectively. The localizer course sector is scetched.
Along an elliptical curve, the field strength is constant. If you look at the diagrams as ordinary
geographical maps, you will see that the dual antenna "field-strength-mountain" is steaper
and more stretched sideways than the single antenna "mountain". This corresponds to a
sharper on/off response on the aircraft's marker beacon instruments.
SINGLE ANTENNA SYSTEM
NETWORK
DI 726
RF OUT RF IN
DUAL ANTENNA SYSTEM
RF OUT
RF IN
5050
HBK914-1