Planar array antenna

A planar array antenna, comprising:

• a multi-layer substrate having an intermediate layer conductor on a laminated face;
• and
• four pieces of planar antenna units formed on said multi-layer substrate, and disposed in a matrix pattern;
• wherein each planar antenna unit comprises:
• first and second slot lines formed in said intermediate layer conductor, and intersecting each other;
• first and second microstrip lines formed on said multi-layer substrate, and traversing said first slot line, respectively, at a position corresponding to both end sides of said first slot line;
• third and fourth microstrip lines formed on said multi-layer substrate, and traversing said second slot line, respectively, at a position corresponding to both end sides of said second slot line;
• a first antenna element coupling to one end of said first microstrip line and one end of said third microstrip line;
• a second antenna element coupling to the other end of said first microstrip line and one end of said fourth microstrip line;
• a third antenna element coupling to one end of said second microstrip line and the other end of said fourth microstrip line;
• a fourth antenna element coupling to the other end of said second microstrip line and the other end of said third microstrip line;
• a fifth microstrip line provided on said multi-layer substrate, a top end side of said fifth microstrip line traversing said first slot line in a center region of said first slot line so as to be electromagnetically coupled to said first slot line, and a sixth microstrip line provided on said multi-layer substrate, a top end side of said sixth microstrip line traversing said second slot line in a center region of said second slot line so as to be electromagnetically coupled to said second slot line, and
• wherein said fifth microstrip lines of two pieces of said planar antenna units adjacent to a first direction are commonly connected, thereby configuring a first common microstrip line, and said sixth microstrip lines of two pieces of said planar antenna units adjacent to a second direction different from said first direction are commonly connected, thereby configuring a second common microstrip line,
• said planar array antenna, further comprising:
• third and fourth slot lines formed on said intermediate layer conductor, and mutually intersecting;
• a seventh microstrip line formed on said multi-layer substrate, a top end side of said seventh microstrip line traversing said third slot line in a center region of said third slot line so as to be electromagnetically coupled to said third slot line;
• and
• an eighth microstrip line provided on said multi-layer substrate, a top end side of said eighth microstrip line traversing said fourth slot line in a center region of said fourth slot line so as to be electromagnetically coupled to said fourth slot line;
• wherein said first common microstrip lines traverse said third slot line, respectively, at a position corresponding to both end sides of said third slot line, and said second common microstrip lines traverse said fourth slot line, respectively, at a position corresponding to both end sides of said fourth slot line.