High-isolation collocated antenna systems

A high-isolation collocated antenna system, comprising:

• a first antenna providing an azimuth radiation pattern which is substantially omnidirectional with areas of radially symmetrical signal strength;
• a second antenna, displaced in elevation from said first antenna, including two antenna element pairs with each said pair comprising:
• first and second vertical dipole elements laterally spaced and substantially symmetrically positioned in areas of radially symmetrical signal strength of said first antenna;
• a first signal conductor for feeding signals from an upper arm of said first vertical dipole element;
• and a second signal conductor for feeding signals from a lower arm of said second vertical dipole element;
• signal cancelling means, coupled to said second antenna, including two junction points each of which directly connects said first and second signal conductors of only one of said two antenna element pairs, for substantially cancelling signals coupled to each said antenna element pair from said first antenna;
• and
• signal combining means, coupled to said two junction points of said signal cancelling means, for combining portions of signals received by each said antenna element pair to provide output signals including signal portions from all antenna elements of said second antenna for providing a first output signal representative of an azimuth antenna pattern with 360.degree. progressive clockwise phase variation and a second output signal representative of an azimuth antenna pattern with 360.degree. progressive counterclockwise phase variation;
• whereby said first and second output signals may be independently coupled to separate receivers for signal processing.

A high-isolation collocated antenna system, comprising:

• a first vertical dipole antenna providing an azimuth radiation pattern which is substantially omnidirectional with areas of radially symmetrical signal strength;
• a second antenna, displaced in elevation from said first antenna, including two antenna element pairs with each said pair comprising two vertical dipole elements laterally spaced and substantially symmetrically positioned in areas of radially symmetrical signal strength of said first antenna;
• signal cancelling means, coupled to said second antenna, for combining signals received by said two vertical dipole elements of each said antenna element pair in an out-of-phase relationship for substantially cancelling signals coupled to each said antenna element pair from said first antenna;
• signal combining means, coupled to said signal cancelling means, for combining portions of signals received by each said antenna element pair to provide output signals including signal portions from all antenna elements of said second antenna;
• and
• means for coupling a selected portion of signals from said first antenna for inclusion in said output signals to cancel signals non-symmetrically coupled from said first antenna to said second antenna as a result of nonuniformities in radiation pattern signal strength, whereby compensation may be provided for multi-path reflections caused by objects within the antenna pattern of said antennas.

A high-isolation collocated antenna system, comprising:

• a first vertical dipole antenna providing an azimuth radiation pattern which is substantially omnidirectional with areas of radially symmetrical signal strength;
• a second antenna including two vertical dipole elements laterally spaced and substantially symmetrically positioned in areas of radially symmetrical signal strength of said first antenna;
• signal cancelling means, coupled to said second antenna, for forming output signals by combining signals received by said two vertical dipole elements in an out-of-phase relationship for substantially cancelling signals coupled to said dipole elements from said first antenna;
• and
• means for coupling a selected portion of signals from said first antenna for inclusion in said output signals to cancel signals non-symmetrically coupled from said first antenna to said second antenna as a result of nonuniformities in radiation pattern signal strength, whereby compensation may be provided for multi-path reflections caused by objects within the antenna pattern of said antennas.

A high-isolation transmit/receive antenna system, comprising:

• a first antenna providing an azimuth radiation pattern having areas of radially symmetrical signal strength;
• a second antenna including first and second radiating elements substantially symmetrically positioned in first and second areas of radially symmetrical signal strength of said first antenna, a first signal conductor for feeding signals of a first phase from said first radiating element, and a second signal conductor for feeding signals of opposite phase, relative to said first phase, from said second radiating element;
• signal cancelling means, coupled to said second antenna, including a junction point directly connecting said first and second signal conductors to directly combine, in an out-of-phase relationship, signals associated with said two radiating elements, for substantially cancelling signals coupled between said first and second antennas to provide output signals;
• and
• means for coupling a selected portion of signals from said first antenna for inclusion in said output signals to cancel signals non-symmetrically coupled from said first antenna to said second antenna as a result of nonuniformities in radiation pattern signal strength, whereby compensation may be provided for multi-path refections caused by objects within the antenna pattern of said antennas.

A high-isolation collocated antenna system, comprising:

• a first antenna providing an azimuth radiation pattern which is substantially omnidirectional with areas of radially symmetrical signal strength;
• a second antenna, displaced in elevation form said first antenna, including two antenna element pairs with each said pair comprising:
• first and second vertical elements laterally spaced and substantially symmetrically positioned in areas of radially symmetrical signal strength of said first antenna;
• a first signal conductor for feeding signals from said first vertical element;
• and a second signal conductor for feeding signals from said second vertical element;
• a horizontally extending member upon which said first antenna is mounted so as to extend upward and upon which said second antenna is mounted below said first antenna so as to extend downward from said member, substantially co-axially with said first antenna;
• signal cancelling means, coupled to said second antenna, including two junction points each of which directly connects said first and second signal conductors of only one of said two antenna element pairs, for combining said signals from said first and second vertical elements in an out-of-phase relationship for substantially cancelling signals coupled to each said antenna element pair from said first antenna;
• and
• signal combining means, coupled to said two junction points of said signal cancelling means, for combining portions of signals received by each aid antenna element pair to provide output signals including signal portions from all antenna elements of said second antenna for providing a first output signal representative of an azimuth antenna pattern with 360.degree. progressive clockwise phase variation and a second output signal representative of an azimuth antenna pattern with 360.degree. progressive counterclockwise phase variation;
• whereby said first and second output signals may be independently coupled to separate receivers for signals processing.