Circular polarization slot antenna apparatus capable of being easily miniaturized
A slot antenna apparatus 10 contains a circuit substrate having a high-frequency circuit arranged therein and a shield case accommodating the circuit substrate. A cross-shaped slot and a feeding pin are formed in an upper plate of the shield case. The cross-shaped slot is composed of first and second slots. The lengths of the slots are different and the slots are perpendicular to each other. The shortest distances from the feeding pin to the first slots are approximately equal. When the power is fed to the upper plate through the feeding pin, the slots are excited to irradiate linearly polarized waves perpendicular to each other, respectively.
1. A slot antenna apparatus, comprising:
a conductor member having a cross-shaped slot composed of a first slot and a second slot therein, the first and second slots being perpendicular to each other;
a feeding pin for feeding power to the conductor member at a predetermined location spaced from the cross-shaped slot; and
a circuit substrate connected to the feeding pin and having a high-frequency circuit arranged therein,
wherein the first and second slots are excited by feeding the power through the feeding pin, and the second slot is excited with a phase difference of about 90 degrees with respect to a resonance mode of the first slot such that the slot antenna apparatus is operated as a circular polarization antenna,
wherein lengths of the first and second slots are approximately equal to each other, and a location of the feeding pin is set such that a shortest distance from the feeding pin to the first slot is different from a shortest distance from the feeding pin to the second slot by a predetermined size.
2. The slot antenna apparatus according to claim 1 , wherein the conductor member is composed of a metal plate, a metal piece made by cutting and erecting a portion of the metal plate is used as the feeding pin, and a front end of the feeding pin is connected to the circuit substrate.
3. The slot antenna apparatus according to claim 2 , further comprising:
a shield case for accommodating the circuit substrate,
wherein one surface of the shield case is used as the conductor member.
4. The slot antenna apparatus according to claim 1 , wherein closed ends of the first and second slots are wider than the other portion thereof.
5. The slot antenna apparatus according to claim 1 , wherein the conductor member has cut portions at locations respectively opposite to closed ends of the first and second slots.