Antenna and RFID tag issuing apparatus
According to one or more embodiments, an antenna comprises a dielectric substrate, a line formed on a first surface of the dielectric substrate, and a ground layer formed on a second surface of the dielectric substrate. A maximum width of the line in a first direction of the first surface is greater than a maximum width of the line in a second direction orthogonal to the first direction. A width of the ground layer in the second direction is equal to the maximum width of the line in the second direction.
1. An antenna, comprising:
a dielectric substrate;
a line on a first surface of the dielectric substrate, a maximum width WL 1 of the line in a first direction of the first surface being greater than a maximum width WL 2 of the line in a second direction orthogonal to the first direction;
a ground layer on a second surface of the dielectric substrate, a width WG 2 of the ground layer in the second direction being equal to the maximum width WL 2 of the line in the second direction; and
a termination resistor connected at an end of the line.
2. The antenna according to claim 1 , wherein
a first end of the line is on a first end side of the first surface in the first direction, and
a second end of the line is on the first end side or a second end side of the first surface in the first direction.
3. The antenna according to claim 2 , wherein the line bends at multiple positions and extends in the first direction multiple times on the first surface of the dielectric substrate.
4. The antenna according to claim 2 , wherein the line extends in the first direction, then bends in the second direction, and again extends in the first direction.
5. The antenna according to claim 2 , further comprising:
a feeding point at the first end of the line, wherein
the termination resistor is at the second end of the line, the termination resistor having a resistance value corresponding to a characteristic impedance of the line.
6. The antenna according to claim 5 , wherein the feeding point and the termination resistor are on the second surface of the dielectric substrate.
7. The antenna according to claim 5 , wherein the ground layer avoids a region around the feeding point and the termination resistor.
8. The antenna according to claim 5 , wherein the feeding point and the termination resistor are on the first surface of the dielectric substrate.
9. The antenna according to claim 1 , wherein the maximum width WL 1 of the line in the first direction is equal to or less than a width W 1 of the dielectric substrate in the first direction.
10. The antenna according to claim 1 , wherein the maximum width WL 2 of the line in the second direction is less than a width W 2 of the dielectric substrate in the second direction.
11. The antenna according to claim 1 , wherein a width WG 1 of the ground layer in the first direction is equal to or greater than the maximum width WL 1 of the line in the first direction and equal to or less than the width W 1 of the dielectric substrate in the first direction.
12. The antenna according to claim 1 , wherein the width WG 2 of the ground layer in the second direction is less than a width W 2 of the dielectric substrate in the second direction.
13. The antenna according to claim 1 , wherein the maximum width WL 2 of the line in the second direction and the width WG 2 of the ground layer in the second direction are set such that the antenna achieves a predetermined increase in the electric field intensity.
14. The antenna according to claim 13 , wherein the increase in the electric field intensity is at least 70% of a difference between the electric field intensity when the width WG 2 is equal to the maximum width WL 2 and the lowest electric field intensity when the width WG 2 is larger than the maximum width WL 2 , where the maximum difference is defined as 100%.
15. The antenna according to claim 1 , wherein the ground layer is in a region of the second surface corresponding to the line on the first surface.
16. The antenna according to claim 1 , further comprising:
a plurality of via holes formed through the dielectric substrate.
17. An antenna, comprising:
a dielectric substrate;
a line on a first surface of the dielectric substrate; and
a ground layer on a second surface of the dielectric substrate, wherein
a termination resistor is on the dielectric substrate and connected at an end of the line,
a maximum width WL 1 of the line in a first direction is greater than a maximum width WL 2 of the line in a second direction orthogonal to the first direction,
a width WG 2 of the ground layer in the second direction is equal to the maximum width WL 2 of the line in the second direction, and
a width WG 1 of the ground layer in the first direction is equal to or greater than the maximum width WL 1 of the line in the first direction and is equal to or less than the width W 1 of the dielectric substrate in the first direction.
18. The antenna according to claim 17 , wherein
a first end of the line is on a first end side of the first surface in the first direction, and
a second end of the line is on the first end side or a second end side of the first surface in the first direction.
19. An RFID tag issuing apparatus, comprising:
an antenna comprising:
a dielectric substrate;
a line on a first surface of the dielectric substrate, a maximum width of the line in a first direction of the first surface being greater than a maximum width of the line in a second direction orthogonal to the first direction;
a ground layer on a second surface of the dielectric substrate, a width of the ground layer in the second direction being equal to the maximum width of the line in the second direction; and
a termination resistor connected at an end of the line; and
a reader/writer configured to communicate with an RFID tag via the antenna.
20. The RFID tag issuing apparatus according to claim 19 , wherein
a first end of the line is on a first end side of the first surface in the first direction, and
a second end of the line is on the first end side or a second end side of the first surface in the first direction.