NCJ Number
57724
Date Published
1976
Length
7 pages
Annotation
THIS PAPER DESCRIBES DESIGN TECHNIQUES AND EXPERIMENTAL RESULTS FOR SEVERAL TYPES OF COVERT SLOT ANTENNAS, AS DEVELOPED BY THE DRUG ENFORCEMENT ADMINISTRATION (DEA) FOR LAW ENFORCEMENT APPLICATIONS.
Abstract
THE ADVANCED TECHNOLOGY DIVISION OF THE DRUG ENFORCEMENT ADMINISTRATION (DEA) HAS APPLIED THE SLOT ANTENNA DESIGN TO A VARIETY OF SPECIALIZED LAW ENFORCEMENT SITUATIONS. A TECHNICAL DESCRIPTION OF THE BASIC SLOT ANTENNA DESIGN IN TERMS OF THE COMPLEMENTARY DIPOLE SHOWS THAT A MAJOR ADVANTAGE OF THIS CLASS OF ANTENNA IS ITS ABILITY TO BE FABRICATED INTO METALLIC OBJECTS AND, IN CONJUNCTION WITH A SMALL TRANSMITTER, PROVIDE COVERT COMMUNICATIONS. SLOT ANTENNAS CAN BE BUILT INTO CONTAINERS, VEHICLE ROOFTOPS, AND TRUNK LIDS. ONE SUCH APPLICATION IS THE USE OF A SLOT ANTENNA AND A BEACON TRANSMITTER MOUNTED IN A STEEL CONTAINER BEING USED BY SUSPECTED CRIMINALS. THE CONTAINER IS TRACKED THROUGH A NUMBER OF INTERMEDIATE DESTINATIONS AND TO AN UNKNOWN FINAL DESTINATION. SINCE THE DEA DOES NOT HAVE CONTROL OF THE CONTAINER WHILE IT IS IN THE HANDS OF THE SUSPECTED CRIMINALS, SATISFACTORY TRACKING PERFORMANCE OF THE ANTENNA/TRANSMITTER SYSTEM HAS TO BE ASSURED EVEN THOUGH THE CONTAINER MAY BE ORIENTED IN ANY CONCEIVABLE POSITION. ANOTHER APPLICATION OF THE SLOT ANTENNA IS ITS USE IN AN UNDERCOVER VEHICLE AS A COMMUNICATIONS AND TRACKING ANTENNA. IN THIS CASE THE SLOT ANTENNA MAY BE CONTRUCTED TO MAKE USE OF AN EXISTING DISCONTINUITY SUCH AS THE GAP BETWEEN THE TRUNK LID AND THE BODY OF THE CAR, OR IT CAN BE FABRICATED AS A SLOT CUT INTO THE ROOF OR BODY OF A CAR. MEASURED ANTENNA RADIATION PATTERNS ARE PRESENTED FOR EACH ANTENNA CONFIGURATION, AND DESIGN FIGURES FOR THE FOLLOWING VARIATIONS ON THE SLOT ANTENNA ARE PROVIDED: THE BASIC AND PRACTICAL SLOT ANTENNAS, THE SLOT ANTENNA ON A CYLINDER AT VHF HI-BAND, THE UHF SLOT ANTENNA, AND THE SLOT ANTENNA MADE FROM A DIELECTRIC SLAB. (AUTHOR ABSTRACT MODIFIED--MHP)