Notch antenna for a radio communications system

Claim 2

An antenna system having a notch type antenna pattern coupled to radio communications apparatus, comprising: antenna means having an omnidirectional antenna beam pattern; and a shield of a predetermined size and shape located a predetermined distance away from said antenna means and capable of being selectively positioned for a predetermined azimuth and elevation so that energy of a selected type is blocked within a relatively small angular sector.

Claim 3

The antenna system as defined by claim 1 wherein said shield comprises an electromagnetic wave shield.

Claim 4

The antenna system as defined by claim 1 wherein said shield comprises an electrically conductive shield of radio signals.

Claim 5

The antenna system of claim 3 wherein said shield is connected to a point of reference potential and operates to block electromagnetic waves within an angular arc encompassed by the size, shape and position of said shield.

Claim 6

The antenna system of claim 1 wherein said shield comprises a grounded electrically conductive shield of electromagnetic waves.

Claim 7

The antenna system as defined by claim 5 wherein said antenna means comprises a receiving antenna, and said radio communications apparatus comprises a radio receiver.

Claim 8

In a signal communications system: first means for generating a single first antenna beam pattern to provide a signal return from a desired signal source accompanied by all undesired interference returns arriving from a plurality of interference sources from any direction except for a narrow sector; second means for generating a single second antenna beam pattern to provide from all of said interference sources a coherent correlated replica of all said undesired interference returns provided by said first antenna beam pattern unaccompanied by said desired signal source; third means coupled to said first and second means for subtracting the returns provided by said first and second antenna beam patterns to produce substantially only said desired signal return as an output of said system; wherein said first means includes a first onmidirectional antenna; and wherein said second means includes a second omnidirectional antenna and an electromagnetic wave shield of a predetermined size and shape located a predetermined distance away from said second omnidirectional antenna and capable of being selectively positioned for a predetermined azimuth and elevation for blocking signals arriving within a relatively small angular sector defined by said shield in its position relative to said second omnidirectional antenna and providing thereby an antenna having a notch beam pattern.

Claim 9

In a signal communications system: first means for generating a single first antenna beam pattern to provide a signal return from a desired signal source accompanied by all undesired interference returns arriving from a plurality of interference sources from any direction except for a narrow sector; second means for generating a single second antenna beam pattern to provide from all of said interference sources a coherent correlated replica of all said undesired interference returns provided by said first antenna beam pattern unaccompanied by said desired signal source; third means coupled to said first and second means for subtracting the returns provided by said first and second antenna beam patterns to produce substantially only said desired signal return as an output of said system; wherein said first means includes a first onmidirectional antenna; and wherein said second means includes a second omnidirectional antenna and an electromagnetic wave shield of a predetermined size and shape located a predetermined distance away from said second omnidirectional antenna and capable of being selectively positioned for a predetermined azimuth and elevation for blocking signals arriving within a relatively small angular sector defined by said shield in its position relative to said second omnidirectional antenna and providing thereby an antenna having a notch beam pattern.

Claim 10

The communications system as defined by claim 7 wherein said shield comprises an electrically conductive shield coupled to a point of reference potential.

Claim 11

The communications system as defined by claim 7 wherein said shield comprises an electrically conductive shield element connected to ground potential.