Array antenna with forced excitation

An array antenna, comprising:

• terminal means for coupling signals;
• a plurality of antenna elements comprising a linear array of at least first, second and third antenna elements for coupling radiated signals;
• first excitation means, coupled between said terminal means and a first group of non-adjacent elements including at least said first and third elements, comprising individual signal transmission paths for coupling a signal component of predetermined relative phase and amplitude to each element of said first group by way of a point of common voltage included in said first excitation means, said individual transmission paths including transmission line means having characteristics equivalent to a quarter wavelength transformer coupled between said point of common voltage and each element of said first group, said wavelength corresponding to approximately the average design frequency;
• second excitation means, coupled between said terminal means and the remaining elements including at least said second element, comprising at least one additional signal transmission path for coupling a signal component of predetermined phase and amplitude to each of said remaining elements;
• and
• tuning means coupled to said point of common voltage for providing tuning for said first group of non-adjacent elements in a desired frequency range;
• whereby signal components in said antenna elements are caused to have a predetermined relationship of phase and amplitude, substantially independently of intercoupling affecting antenna elements of the array antenna.

An array antenna, comprising:

• terminal means for coupling signals;
• five antenna elements comprising a linear array of first, second and third elements preceded by a leading element and followed by a trailing element;
• first excitation means coupled between said terminal means and a first group of non-adjacent elements consisting of said first and third elements, comprising individual signal transmission paths for coupling a signal component of predetermined relative phase and amplitude to each element of said first group by way of a first point of common voltage included in said first excitation means, said individual transmission paths including transmission line means coupled between said first and third elements and having predetermined electrical characteristics effective for substantially preventing coupling of intercoupling effects occurring at said first and third elements;
• second excitation means, coupled between said terminal means and said second, leading and trailing elements, comprising individual signal transmission paths for coupling a signal component of predetermined phase and amplitude to each of said second, leading and trailing elements by way of a second point of common voltage included in said second excitation means, said individual transmission paths each including transmission line means coupled between said second, leading and trailing elements and having predetermined electrical characteristics effective for substantially preventing coupling of intercoupling effects occurring at said second, leading and trailing elements;
• first tuning means coupled to said first point of common voltage for providing tuning in a desired frequency range;
• and
• second tuning means coupled to said second point of common voltage for providing tuning in said desired frequency range;
• and
• whereby signal components coupled to said antenna elements are caused to have a predetermined relationship of phase and amplitude, substantially independently of intercoupling affecting antenna elements of the array antenna.

An array antenna, comprising:

• terminal means for coupling signals;
• a plurality of antenna elements comprising at least first, second and third antenna elements, said antenna elements being slots in the form of elongated windows in a conductive surface, for coupling radiated signals;
• first excitation means, coupled between said terminal means and said first and third elements, comprising first and third signal transmission paths for coupling signal components of predetermined relative phase and amplitude to said first and third elements, respectively, by way of a point of common voltage included in said first excitation means, said first and third transmission paths including transmission line means having characteristics equivalent to a quarter wavelength transformer coupled between said point of common voltage and each of said first and third elements, said wavelength corresponding to approximately the average design frequency;
• second excitation means, coupled between said terminal means and said second element, comprising a second signal transmission path for coupling to said second element a signal component of predetermined phase and amplitude relative to said signal components coupled to said first and third elements;
• and
• tuning means coupled to said point of common voltage for providing impedance matching for said first and third elements in a desired frequency range;
• whereby signal components in said antenna elements are caused to have a predetermined relationship of phase and amplitude, substantially independently of intercoupling affecting antenna elements of the array antenna.

An end-fire array antenna, comprising:

• terminal means for coupling signals;
• a plurality of antenna elements, comprising at least first, second and third monopole antenna elements;
• first excitation means for coupling signals from said terminal means to said first and third elements for providing radiated signals of different phase at one element relative to the other, said first excitation means including transmission line means having characteristics equivalent to a quarter wavelength transformer coupled to said third element and transmission line means equivalent to the series combination of a quarter wavelength transformer and a half wavelength transmission line coupled to said first element, said wavelength corresponding to approximately the average design frequency;
• second excitation means for coupling signals from said terminal means to said second element with a predetermined phase and amplitude different from said signals coupled to said first and third elements;
• and
• tuning means coupled to said first excitation means for providing double tuning in a desired frequency range;
• whereby said excitation means are effective to cause signals in said antenna elements to have a predetermined relationship of phase and amplitude resulting in an antenna pattern having a principal beam in a forward direction.

An end-fire slot array antenna, comprising:

• terminal means for coupling signals;
• a plurality of slot antenna elements, comprising at least first, second and third antenna elements;
• first excitation means for coupling signals from said terminal means to said first and third elements for providing radiated signals of different phase at one element relative to the other, said first excitation means including transmission line means having predetermined electrical characteristics coupled to each of said first and third elements for isolating said first element from intercoupling effects affecting said third element and isolating said third element from intercoupling affects affecting said first element;
• and
• second excitation means for coupling signals from said terminal means to said second element with a predetermined phase and amplitude different from said signals coupled to said forward and rear elements;
• whereby said excitation means are effective to cause signals in said antenna elements to have a predetermined relationship of phase and amplitude resulting in an antenna pattern having a principal beam in a forward direction.

A low-profile array antenna suitable for aircraft installation, comprising:

• a connector for coupling signals;
• a first planar conductor pattern comprising first, second and third monopole antenna elements each less than one-eighth wavelength in height;
• a second planar conductor pattern comprising first excitation means for coupling said connector to said first and third elements by way of quarter wavelength transformer means for coupling signal components, second excitation means for coupling said connector to said middle second element, and tuning means coupled to said first excitation means for providing double tuning in a desired frequency range;
• and
• a protective cover of radiation transmissive material;
• wherein said wavelength corresponds to approximately the average design frequency, and whereby the antenna is suited for aircraft installation with reduced visual and air flow interference.

An array antenna comprising:

• a connector;
• first, second and third monopole antenna elements;
• three inductive tuners, one connected to each element;
• a first excitation circuit comprising a quarter wavelength transformer connected between said third element tuner and a point of common voltage, a quarter wavelength transformer in series with a half wavelength transmission line connected between said first element tuner and said common voltage point and a reactive tuning circuit connected between said common voltage point and said connector;
• a second excitation circuit comprising a directional coupler and transmission line section connected in series between said second element tuner and said connector, and a reactive tuning circuit coupled to said transmission line section;
• a protective cover;
• and
• a base member for supporting said antenna elements.