Radiant energy type intrusion alarm system

Claim 2

AN INTRUSION DETECTOR SYSTEM COMPRISING DIRECTIONAL TRANSMITTING AND RECEIVING ANTENNAE POSITIONED ON A COMMON BASE LINE IN AN AZIMUTH PLANE AND EACH HAVING A PRINCIPAL AXIS OF DIRECTIVITY ANGLED TO SAID LINE TO DEFINE A TRIANGLE THEREWITH, MEANS APPLYING ENERGY TO SAID TRANSMITTING ANTENNA, AND DETECTOR MEANS RESPONSIVELY CONNECTED TO THE RECEIVING ANTENNA, SAID ANTENNAE HAVING RESPECTIVE FIELD PATTERNS DEFINED IN POLAR COORDINATES REFERENCED TO THEIR DIRECTIONAL AXES WHICH VERY AS A FUNCTION OF COS 20, WHERE 0 IS THE COORDINATE ANGLE, WITHIN A DETECTION REGION SUBSTANTIALLY INCLUDING SAID TRIANGLE SO THAT THE RECEIVED SIGNAL FROM AN INTRUDING SUBJECT IN THE AZIMUTH PLANE REMAINS SUBSTANTIALLY CONSTANT AT DIFFERENT POINTS OF ENTRY WITHIN SUCH DETECTION REGION.

Claim 3

AN INTRUSION DETECTOR SYSTEM COMPRISING TWO PAIRS OF DIRECTIONAL TRANSMITTING AND RECEIVING ANTENNAE, THE TRANSMITTING AND RECEIVING ANTENNAE OF EACH PAIR BEING POSITIONED ON A COMMON BASE LINE AND EACH HAVING A PRINCIPAL AXIS OF DIRECTIVITY ANGLED TO SAID LINE TO DEFINE A TRIANGLE THEREWITH, MEANS APPLYING ENEGY TO THE TRANSMITTING ANTENNA OF EACH PAIR, AND DETECTOR MEANS RESPONSIVELY CONNECTED TO THE RECEIVING ANTENNAE OF THE TWO PAIRS, INCLUDING MEANS RESPONSIVE SELECTIVELY TO A DIFFERENCE BETWEEN THE RECEIVED SIGNALS IN THE TWO RECEIVING ANTENNAE, SAID ANTENNAE IN EACH PAIR HAVING RESPECTIVE FIELD PATTERNS SO SHAPED WITHIN A DETECTION REGION SUBSTANTIALLY INCLUDING SAID TRIANGLE THAT THE RECEIVED SIGNAL FROM AN INTRUDING SUBJECT IN THE AZIMUTH PLANE REMAINS SUBSTANTIALLY CONSTANT AT DIFFERENT POINTS OF ENTRY WITHIN SUCH REGION, THE ANTENNAE OF ONE PAIR BEING ARRANGED WITH FIELD PATTERNS IN OVERLAPPING RELATIONSHIP WITH FIELD PATTERNS OF THE OTHER PAIR.

Claim 4

AN INTRUSION DETECTOR SYSTEM COMPRISING TWO PAIRS OF DIRECTIONAL TRANSMITTING AND RECEIVING ANTENNAE, THE TRANSMITTING AND RECEIVING ANTENNAE OF EACH PAIR BEING POSITIONED ON A COMMON BASE LINE AND EACH HAVING A PRINCIPAL AXIS OF DIRECTIVITY ANGLED TO SAID LINE TO DEFINE A TRIANGLE THEREWITH, MEANS APPLYING ENEGY TO THE TRANSMITTING ANTENNA OF EACH PAIR, AND DETECTOR MEANS RESPONSIVELY CONNECTED TO THE RECEIVING ANTENNAE OF THE TWO PAIRS, INCLUDING MEANS RESPONSIVE SELECTIVELY TO A DIFFERENCE BETWEEN THE RECEIVED SIGNALS IN THE TWO RECEIVING ANTENNAE, SAID ANTENNAE IN EACH PAIR HAVING RESPECTIVE FIELD PATTERNS SO SHAPED WITHIN A DETECTION REGION SUBSTANTIALLY INCLUDING SAID TRIANGLE THAT THE RECEIVED SIGNAL FROM AN INTRUDING SUBJECT IN THE AZIMUTH PLANE REMAINS SUBSTANTIALLY CONSTANT AT DIFFERENT POINTS OF ENTRY WITHIN SUCH REGION, THE ANTENNAE OF ONE PAIR BEING ARRANGED WITH FIELD PATTERNS IN OVERLAPPING RELATIONSHIP WITH FIELD PATTERNS OF THE OTHER PAIR.