Microstrip array antenna

A planar microstrip array antenna with beam tilt, comprising an array, formed of a plurality of circularly polarized wave radiating elements each of which includes a circular feeding patch having a pair of diametrically opposed notches, and a feed line coupled to the radiating elements, wherein

• said circularly polarized wave radiating elements are grouped into a plurality of pairs, one radiating element in each said pair being oriented with respect to said notches at a rotational angle .alpha..degree. to the other radiating element, within the plane of the planar antenna;
• said feed line is provided with a plurality of pairs of terminal feeding portions corresponding individually to the pairs of circularly polarized wave radiating elements, said terminal feeding portions for each said pair of radiating elements diverging individually from a first diverging portion and being equal in electrical length;
• said feed line is further provided with additional feeding portions connecting the first diverging portions of adjacent pairs of radiating elements to an additional diverging portion, one of the additional feeding portions including a phase shift portion;
• said angle .alpha..degree. is set so as to satisfy an equation given by
• .theta..apprxeq.sin.sup.-1 (.alpha..degree..lambda..sub.o /2.pi.d),
• where .theta. is a desired beam tilt angle, d is the distance between the circularly polarized wave radiating elements in each pair, and .lambda..sub.o is the wavelength of electromagnetic waves within a free space;
• said feed line being formed on a printed feeder board so as to be coupled electromagnetically to the circularly polarized wave radiating elements;
• said radiating elements being formed on a printed radiation board;
• and
• further comprising a body made of electrically conductive material in the form of a rectangular plate having a front face and a peripheral flange, and wherein a first dielectric sheet made of synthetic resin foam is superposed on the front face of the body, said printed feeder board is superposed on the first dielectric sheet, a second dielectric sheet made of synthetic resin foam is superposed on the printed feeder board, said printed radiation board is superposed on the second dielectric sheet, a protector plate made of synthetic foam is superposed on the printed radiation board, and a cover is superposed on the protector plate, the antenna further including frame means for joining the respective edge portions of said cover and said body together.

A planar microstrip array antenna with beam tilt, comprising an array formed of a plurality of circularly polarized wave radiating elements each of which includes a circular feeding patch having a pair of diametrically opposed notches, and a feed line coupled to the radiating elements, wherein

• said circularly polarized wave radiating elements are grouped into a plurality of pairs, one element of each pair being oriented with respect to said notches at a rotational angle of 90.degree. to the other radiating element of each pair, within the plane of the planar antenna, the elements of adjacent pairs of wave radiating elements being in straight line relation to one another;
• said feed line is provided with a plurality of pairs of first feeding portions corresponding respectively to the pairs of circularly polarized wave radiating elements diverging respectively from a first diverging portions, said first feeding portions being equal in electrical length;
• said feed line is further provided with additional feeding portions connecting the first diverging portions of adjacent pairs of radiating elements to a second diverging portion, said additional feeding portions being equal in electrical length;
• said feed line is further provided with further additional feeding portions connecting adjacent two second diverging portions to a third diverging portion, one of said further additional feeding portions including a phase shift portion for producing a phase difference of 180.degree..