TELE-TECH & - AmericanRadioHistory.Com

ASDE Radar
(Continued from page 87)
No Antenna Design
Guesswork Here!
The difficult problem of "broadbanding" curtain antennas used
for international broadcasting was mastered for the first time
in this recent Trylon installation. Here, two curtain antennas were
designed for bandwidths of ±15% of center frequencies
(13.5 and 19.85 mc) with a maximum VSWR of only 1.5. Careful
consideration of side lobes and back radiation was necessary to reduce
interference as well as to achieve the hard -to- realize 5 to 10%
improvement in readability compared with conventional
rhombics of the same gain.
The experience of Try lon antenna specialists is no better
demonstrated than by the actual "on the air" field measurements
made after the completion of this complicated installation.
Not only did the radiation pattern remain essentially as
predicted in Trylon's initial calculations, but a gain of 18 db
over a quarter -wave dipole was obtained.
Trylon welcomes the opportunity to apply the same sound
engineering approach to every phase of your next
antenna installation -whether for AM, FM, TV, Microwave,
or long -distance communications.
TRYLON
ANTENNA DESIGN, FABRICATION,
INSTALLATION
GALVANIZED STEEL TOWERS
ANTENNA SELECTOR, SHORTING,
and SLEWING SWITCHES
HEAVY -DUTY ANTENNA ROTATORS
WIND TURBINE COMPANY, West Chester, Pa.
In Canada: The Wind Turbine Company of Canada, Ltd., Toronto 9, Ontario
side the ASR and PAR indicators.
This installation was made just before
the new tower was put in operation,
and the radar was used there
for a period of about one year.
Fig. 2 is a photograph taken in the
control tower showing the location
of the PPI. It should be noted that
this picture is a deliberate double
exposure. An exposure was made
during daylight with a black mask
over the cathode -ray tube and, without
moving the camera, a second
exposure was made at night to catch
the PPI display. This picture was
taken before the second indicator
was placed in the approach control
room.
Fig. 1 is a photograph of the
PPI display showing most of Idle -
wild Airport.
Although no formal report covering
the use of ASDE at Idlewild
was issued, there is no question
that the controllers made good use
of the equipment. The experimental
equipment was not considered
to be integrated into their operating
procedures, but the controllers
found it convenient and reassuring
to glance frequently at the display
at night or during periods of poor
visibility. Further, they were able
to make some improvements in
their operating procedures based on
information learned from ASDE.
During the time that this modification
program was under way, the
Air Navigation Development Board
came into existence. Since ASDE
was considered part of the Common
System equipment, it came under
the jurisdiction of ANDB. However,
the Air Force continued to
handle the actual administration of
the program from Rome Air Development
Center. The operational
tests that had been made with the
original Taxi Radar and the early
tests of the equipment modified for
greater resolution had effectively
demonstrated the potentialities of
radar in the control of surface traffic.
There was general agreement
among the agencies concerned that
the program should be pursued further,
and specifications for an Engineering
Model of ASDE were
prepared, based on the results ob-
(Continued on page 182)
180 For product information, use inquiry cord on pages 209 -210.
Tele -Tech & ELECTRONIC INDUSTRIES June 1956