Microstrip antenna and information apparatus

A microstrip antenna corresponding to a rectangular resonator, the rectangular resonator having:

• a first side and a second side being parallel to a first direction and having a length corresponding to 3/2 wavelength;
• and
• a third side and a fourth side being parallel to a second direction orthogonal to the first direction, the rectangular resonator having a shape notched from each of the first side and the second side toward a center of the rectangular resonator,
• the microstrip antenna comprising:
• a first portion constituting a periphery of the notched shape;
• and
• a second portion and a third portion facing each other across the first portion,
• the notched shape allowing the first portion to contribute to a radiation characteristic for the second portion and the third portion,
• the first portion, the second portion, and the third portion each having a length corresponding to ½ wavelength in the first direction,
• the first portion having a width in the second direction that is narrower because of the notched shape than a width of the second portion and the third portion in the second direction, and
• either the second portion or the third portion being provided with a feeding point.