Monopole/crossed slot single antenna direction finding system

An apparatus for determining an angle of arrival of a signal, the apparatus comprising:

• a monopole/crossed slot antenna for receiving the signal, said antenna comprising:
• a first ground plane of conductive material defining first and second intersecting slots therein;
• a second ground plane of conductive material positioned substantially parallel to said first ground plane;
• a first stripline of a conductive material located between and substantially parallel to said first and second ground planes;
• a second stripline of a conductive material located between and substantially parallel to said first and second ground planes, said second stripline being positioned substantially perpendicular to said first stripline and intersecting said first stripline at a center thereof;
• and
• a monopole connected at the intersection of said first and second striplines and extending through the intersection of the first and second slots defined within said first ground plane;
• antenna configuring means for simultaneously configuring said monopole/crossed slot antenna according to both a first and a second predetermined reception pattern such that a signal received by said monopole/crossed slot antenna is transformed to both a first subsignal by said monopole/crossed slot antenna configured according to the first predetermined reception pattern and to a second subsignal by said monopole/crossed slot antenna configured according to the second reception pattern;
• means, responsive to said antenna configuring means, for determining a difference in amplitude between the first and second subsignals;
• and
• conversion means for converting the amplitude difference determined by said amplitude difference determining means between the first and second subsignals to an angular value corresponding to an angular difference between an angle at which the signals were received by said monopole/crossed slot antenna and a predetermined reference direction.

A method for determining an angle of arrival of a signal with a monopole/crossed slot antenna, the method comprising the steps of:

• simultaneously configuring the monopole/crossed slot antenna according to both first and second predetermined reception patterns;
• receiving the signal with the monopole/crossed slot antenna simultaneously configured according to both the first and second predetermined reception patterns;
• transforming the same received signal according to both the first and second reception patterns into first and second transformed subsignals, respectively;
• determining a difference in amplitude between the first and second transformed subsignals;
• and
• converting the amplitude difference between the first and second transferred subsignals into the angle of arrival of the received signal from a predetermined reference direction.