JP2000165134A - Patch antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circularly polarized wave patch antenna where the axial ratio and the matching behavior can be set mechanically. SOLUTION: In a patch 1 made of a conductor formed on a dielectric base 4 where a power feeding point 12 is provided, a plurality of finger-like slots 16 that are orthogonal to a concerned side and extend toward an inside of the patch 1 are formed to two adjacent sides Ed1, Ed2. The axial ratio and the matching can be optimized by optimizing a length Len of the finger slots 16, a width W and a mutual separation interval Sep. A rectangular slot 7 as an opening may be provided to the patch 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circularly polarized patch antenna used for a mobile communication system and the like,
The present invention relates to a patch antenna whose axis ratio has been corrected.

[0002]

2. Description of the Related Art In the field of mobile communications and the like, patch antennas in which a patch made of a conductor is arranged on the surface of a plate-shaped dielectric have been widely used in order to reduce the size of the antenna. As the circularly polarized patch antenna, for example, as shown in FIG. 6, a rectangular patch 51 having one side length of L1 and L2 is formed on the surface of the dielectric 50, and the feeding point 52 is accurately positioned. In some cases, the adjustment between the matching (matching) and the axial ratio at the used frequency f1 can be performed (see FIG. 6, Sharma et al., "Analysis and o").
ptimized design of single feed circularly polarize
d microstrip antennas ", IEEE TAP 1983, vol.31, pp.
949-955). A ground plane 53 is provided on the back side of the dielectric 50.

[0003] Further, D. Sauchez-Hernandez, G. Passiop, which can be used at two different frequencies f1 and f2, are disclosed.
oulos Ian, D. Robertson, "single fed dual band circ
ularly polarized microstrip patch antennas ", 26th
EuMc 9-12, september 1996, Prague, 273-277. FIG. 7 shows such a circularly polarized patch antenna (dual frequency antenna) usable at two different frequencies. In this antenna, a rectangular patch 5 receiving power supply from a feed point 56 is provided on the surface of a dielectric 55.
7 are provided, and the patch 57 is configured to match the first frequency f1. Further, two adjacent sides of the four sides of the patch 57 are provided with slit portions 58 that are cut inward. The shape of the slit portion 58 is an inverted L-shape in which a portion parallel to the corresponding side is long. If the slit width of the slit portion 58 is WLSL and the length of the portion of the slit portion 58 parallel to the side is LSL, the slit portion 58 has a filter effect by adjusting the WLSL and LSL. Thus, resonance can be achieved with respect to the second frequency f2. As a result, this patch antenna
It can be used at two different frequencies f1 and f2, and functions as a dual frequency antenna. In this antenna, the axial ratio can be adjusted depending on the size and position of the slit portion 58.

[0004]

One of the problems with prior art patch antennas, such as that shown in FIG. 6, relates to the need to make adjustments between axial ratio and matching, and requires a single feed. In addition, since a simple structure is used, the degree of freedom is insufficient to set the axial ratio and the matching at the same time in an optimal manner.

When it is desired to provide a monopole or dipole above the patch antenna, it is sometimes desirable to provide a square or rectangular opening (slot) in the conductor patch. If provided,
Adjustment of the position of the feed point is not easy, and merely changing the position of the feed point cannot compensate for variations in the axial ratio with respect to matching.

As shown in FIG. 7, in a patch antenna provided with an inverted L-shaped slit portion to perform a dual frequency mode, adjustment of an axial ratio and matching when a slot (opening) is provided inside the patch. Therefore, it is difficult to arrange a monopole on the patch antenna.

Several methods have been proposed to mechanically set the axial ratio and the matching at a plurality of operating frequencies at the same time, but they provide two different arrays on the same substrate. This requires a lot of space and the antenna structure itself is large. To add a reverse L-shaped slit,
If internal slots are desired, the method is not satisfactory because of the shift in axial ratio and matching.

[0008] Practical communication systems require low cost, small, circularly polarized antennas with good axial ratio and matching at the same time. Actual patch antennas provide good matching or good axial ratio, but they are not simultaneously satisfied. To do so, an adjustment between the two performances will be made.

An object of the present invention is to solve the drawbacks of the conventional method and to provide a patch antenna used for applications such as personal communication, which can mechanically set an axial ratio and a matching behavior. To provide.

[0010]

A patch antenna according to the present invention has a dielectric substrate, a substantially rectangular patch formed of a conductor formed on the dielectric substrate, and a feeding point for feeding power to the patch. Finger-like slots are formed on two adjacent sides of the patch, each of which extends perpendicularly to the side toward the inside of the patch.

When a circularly polarized patch is formed on a planar structure, the gain obtained is determined by the resonance length of the rectangular patch. Therefore, the position of the feeding point in the rectangular patch determines the position of the optimal adjustment between the axial ratio and the matching. On the other hand, when an internal dipole is provided by providing a slot-shaped opening (hole), it is relatively difficult to perform good adjustment between matching performance and axial ratio performance. Therefore, in the present invention, by providing a group of finger-like slots extending in a direction perpendicular to the sides of the rectangular patch, the axial ratio performance and the matching performance of the patch antenna can be simultaneously set mechanically. Here, “mechanical” means that an optimum value can be immediately obtained by performing computer simulation of the antenna. Accurate sizing of all at the frequency of interest allows a planar structure or patch antenna to provide good matching and a low axial ratio while using only its single feed point.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the drawings. Fig. 1 (a), (b)
3A and 3B are a plan view and a perspective view, respectively, of the patch antenna according to the first embodiment of the present invention.

A patch 1 made of a rectangular conductor having a predetermined size.
Is formed on the surface of the dielectric substrate 4 having a thickness TC and a dielectric constant P1. The ground plate 3 is formed on the back surface side of the dielectric substrate 4. The lengths of two adjacent sides of the patch 1 are L1 and L2, respectively (here, L1> L2).
Patch 1 has two adjacent sides D1 and D, respectively.
2, a rectangular slot (opening) 7 is provided.
In FIG. 1 (a), the hatched portions indicate
This shows that a part of the rectangular patch 1 has been removed and the underlying dielectric substrate 4 is exposed and visible.

If the corner of the patch 1 that is closest to the rectangular slot is the corner C, the position of the corner of the rectangular slot 7 that is closest to the corner C is from the corner C of the patch 1 This is a position moved by E1 in the side direction of the length L1 and by E2 in the side direction of the length L2. Feeding point 12 to patch 1
Is a corner D of the corner of the patch 1 opposite to the corner C.
From the position G1 in the direction of the side L1 and G2 in the direction of the side L2. Then, power is supplied to the power supply point 12 from the back side of the patch 1 through the dielectric substrate 4 by a power supply line (not shown).

Further, in this patch antenna, N finger-like slots 16 are provided on each of two sides Ed1 and Ed2 sandwiching the corner C among the sides of the patch 1.
Each slot 16 extends inwardly of the patch 1 in a direction orthogonal to the side of the corresponding patch 1. Here, the length of the slot 16 (the length in the direction orthogonal to the side of the patch 1) is Len, the width of the slot 16 is W1, and the separation distance between the slots is Sep.

In this patch antenna, by optimizing these parameters Len, W and Sep, an optimal axial ratio and matching can be obtained at the first frequency f1. In addition, the length Len and the width W1 may be changed for each slot 16, and the separation distance Sep between the slots may be different.

Hereinafter, a case where a patch antenna adapted to 2.2 GHz as a working frequency is configured will be described with reference to numerical values.

The thickness TC of the dielectric substrate 4 is 3.2.
mm, a polyphenylene oxide (PPO) having a dielectric constant P1 of 10 is used.
Patch 1 was printed so that 9.32 mm and L2 was 18.29 mm. This patch 1 has a D1 of 7 mm,
The rectangular slot 7 whose D2 is 6.726 mm
Is 3.5 mm and E2 is also 3.5 mm.

The feed point 12 has a G1 of 8.26 m.
m and G2 were arranged so as to be 8.1 mm. In addition, three finger-like slots 16 are provided on the sides Ed1 and Ed2 of the patch 1, respectively. Width W of slot 16
1 was 0.5 mm, and the length Len was 2 mm. The separation distance Sep between the slots was 0.5 mm. W1, L
en and Sep were the same irrespective of the slot 16.

FIG. 2 shows the results obtained by simulation of the axial ratio and matching frequency change of the patch antenna whose sizes have been determined as described above. Here, the matching is performed by using S among the S parameters.
It is shown as a value of 11 components (the ratio of the reflected wave to the incident wave). From this, the axial ratio centering on the matching at a frequency of 2.2 GHz is shown. The matching in this case is better than 14 dB and the axial ratio is less than 1 dB.

FIG. 3 shows a radiation pattern of the above-mentioned patch antenna, and shows a pick gain of 4.5 dBc.

FIG. 4 shows a 2.2G antenna in a patch antenna.
6 is a graph showing in detail a frequency change of a gain and an axial ratio in the vicinity of Hz.

Next, a second embodiment of the present invention will be described. The patch antenna of the present invention functions as a dual-frequency antenna by stacking two patches via a dielectric. Hereinafter, an example configured as a dual frequency patch antenna will be described. FIGS. 5 (a) and 5 (b) respectively show
It is a perspective view and a top view partially showing the patch antenna of the second embodiment.

On the patch antenna shown in FIGS. 1 (a) and 1 (b),
A dielectric layer 25 having a thickness of TC1 and a dielectric constant of P2 is formed, and a second conductive layer is formed on the surface of the dielectric layer 25.
Are formed. The planar shape of the second patch 22 is as shown in FIG. That is, the second
Is a rectangular patch whose adjacent sides are L11 and L12, respectively.
2, a rectangular slot (opening) 28 whose adjacent two sides are D3 and D4, respectively, like the patch (hereinafter referred to as the first patch) 1 in the first embodiment. And N1 finger-like slots 34 are formed. The corner of the slot 28 is located at a position shifted from the corner C1 of the second patch 22 by E3 in the L11 direction and by E4 in the L12 direction. The finger-like slots 34 are respectively provided on two sides Ed11 and Ed22 sandwiching the corner C of the second patch 22. The slot 34 is provided with a length Len1 orthogonal to a corresponding side of the second patch 22, and has a width of W11. The separation distance between the slots 34 is S
ep1. These parameters W11, Len1, and Sep may be different for each slot. In the second patch 22, by optimizing the parameters W11, Len1, and Sep1, an optimal axial ratio and matching can be obtained at the second frequency f2 different from the first frequency f1.

As described above, the patch antenna of the second embodiment functions as a dual-frequency circularly polarized patch antenna that operates at both the first frequency f1 and the second frequency f2.

[0026]

As described above, according to the present invention, by providing a group of finger-like slots extending in a direction perpendicular to the sides of a rectangular patch in the patch, the axial ratio performance and the matching performance can be simultaneously achieved. In addition, there is an effect that the setting can be performed mechanically.

[Brief description of the drawings]

FIG. 1A is a plan view showing a patch antenna according to a first embodiment of the present invention, and FIG. 1B is a perspective view of the patch antenna.

FIG. 2 is a graph showing matching with respect to frequency and an axial ratio in the patch antenna shown in FIGS. 1 (a) and 1 (b).

FIG. 3 is a radiation pattern of the patch antenna shown in FIGS. 1 (a) and 1 (b).

FIG. 4 is a graph showing a frequency change of a gain and an axial ratio in the vicinity of 2.2 GHz in the patch antenna shown in FIGS. 1 (a) and 1 (b).

FIG. 5A is a partially transparent perspective view showing a patch antenna according to a second embodiment of the present invention, and FIG. 5B is a top view of the patch antenna.

FIG. 6 is a perspective view showing a conventional circularly polarized patch antenna.

FIG. 7 is a perspective view showing a conventional dual frequency patch antenna.

[Explanation of symbols]

 1, 22 patch 3 ground plane 4 dielectric substrate 7, 28 rectangular slot 12 feeding point 16, 34 finger-like slot 25 dielectric layer

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 5J021 AA02 AA05 AA09 AA13 AB06 CA03 GA08 HA05 HA10 JA02 JA03 JA06 5J045 AA01 AA02 AA16 AB05 CA04 DA06 DA10 EA07 FA02 GA01 HA03 LA01 MA07 NA01

Claims (9)

[Claims] 1. A patch comprising: a dielectric substrate; a substantially rectangular patch formed on the dielectric substrate and made of a conductor; and a feeding point for feeding the patch, two adjacent sides of the patch: Patch antennas, each having a finger-like slot extending perpendicularly to the side toward the inside of the patch. 2. The patch antenna according to claim 1, wherein a rectangular slot is formed as an opening in the patch. 3. The patch antenna according to claim 1, wherein a plurality of finger-like slots are formed on each side of the patch. 4. The patch antenna according to claim 3, wherein the length and width of the finger-like slots are different for each finger-like slot. 5. A finger-like slot, wherein three or more finger-like slots are formed on each side of the patch, and the length and width of the finger-like slots are different for each finger-like slot. The patch antenna according to claim 1, wherein separation distances between the patch antennas are unequal. 6. The method according to claim 1, wherein a length and a width of the finger-like slot and a separation distance between the finger-like slots are optimized so that an optimum axial ratio and matching can be obtained at a predetermined frequency. The patch antenna according to any one of claims 3 to 5. 7. A dielectric substrate, a first substantially rectangular patch formed of a conductor formed on the dielectric substrate, and a dielectric layer formed to cover the dielectric substrate and the first patch. And a substantially rectangular second patch formed of a conductor formed on the dielectric layer, wherein a first rectangular slot is formed as an opening in the first patch, and an opening is formed in the second patch. A first finger-like slot extending toward the inside of the first patch at right angles to the side is formed on each of two adjacent sides of the first patch. A patch antenna, wherein a second finger-like slot is formed on each of two adjacent sides of the second patch, the second finger-like slot being orthogonal to the side and extending toward the inside of the second patch. 8. The patch antenna according to claim 7, wherein a plurality of finger-like slots are formed on each side. 9. The method according to claim 1, further comprising optimizing a length and a width of the finger-like slot and a separation distance between the finger-like slots.
In order to obtain an optimal axial ratio and matching at a predetermined first frequency, and the second patch
9. The patch antenna according to claim 8, wherein an optimum axial ratio and matching are obtained at a second frequency different from the frequency of the patch antenna.