JPH06232625A - Dual resonance inverted-f antenna - Google Patents

Abstract

PURPOSE:To provide the dual resonance inverted-F antenna with a wide band and less gain deterioration. CONSTITUTION:A main radiator 2 is provided on a grounded conductor plate 1 and one end of the major radiator 2 is connected electrically to the grounded conductor plate 1 via a short-circuit piece 3. A feeder 5 is connected to a feeding point 4 of the major radiator 2, and the feeder 5 is connected to a transmitter- receiver (not shown). A sub radiator 6 is provided to an upper part of the major radiator 2, a short-circuit piece 7 is connected electrically from one end of the sub radiator 6 to a ground conductor plate 1 separately from the short- circuit piece 3. The major radiator 2 and the sub radiator 6 may be a conductive material and, for example, copper is suitable for the material. The grounded conductor plate 1 is connected to a case of a portable radio equipment usually. Since the major radiator 2 is connected to the grounded conductor plate 1 and the sub radiator 6 is connected to the grounded conductor plate 1 separately respectively, the dual resonance inverted-F antenna with a broad band and less gain deterioration within a band of the operating frequency is provided while keeping the size of the antenna small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-resonance inverted-F antenna used in a portable radio device, and more specifically, a multi-resonance inverted-F antenna whose sub-radiator is grounded separately from a main radiator. It relates to the structure of a resonant inverted F antenna.

[0002]

2. Description of the Related Art A multi-resonant inverted F antenna has been well known, and various improvements have been made. The multi-resonance inverted-F antenna has a conductor radiating plate arranged to oppose a grounded conductor plate, and one end of the conductor radiating plate is connected to the grounded conductor plate. When this structure is viewed from the side, it is as if it had an F-shape, so it is called as described above. As an improvement over the conventional multi-resonance inverted F antenna, for example, JP-A-60-58704 (multi-resonance inverted F antenna), JP-A-61-41205 (broadband transmission line antenna), and U.S. Pat. No. 4,070,676 (Multiple). Reso
nonce Radio Frequency Mic
rostripe anne Structur
e), U.S. Pat. No. 4,131,893 (Microstr
ip Radiator with Folded R
essonant Cavity), and US Pat.
218,681 (Multiple Band Cir)
circularly Polarized Microstr
ip Antenne).

[0003]

Problems to be Solved by the Invention JP-A-60-5870
In the multi-resonance type inverted F antenna disclosed in 4, there are two frequencies at which the return loss becomes low, as shown in FIG. 3, and multiple resonance occurs. However, in the band including the above two frequencies, the gain is not constant and deteriorates. In the wideband transmission line antenna disclosed in Japanese Patent Laid-Open No. 61-41205, the gain is constant and the deterioration is small, but if the distance between the conductor plates is shortened in order to reduce the shape of the antenna, the effect of widening the band is weakened. Becomes Further, in the microstrip antenna disclosed in U.S. Pat. No. 4,070,676, if the distance between the conductor elements is shortened, the effect of widening the band is reduced. Furthermore, the microstrip radiator of US Pat. No. 4,131,893 has a complicated structure, and the radiator (radiator) to be fed is a half-wavelength type, so there is a limit to miniaturization. Also, US Pat. No. 4,218,68
In the microstrip antenna disclosed in 1), if the distance between the conductor elements is shortened, the effect of widening the band is weakened as described above, and the radiator to be fed is a half-wave type, so that the size is reduced. Is limited.

As described above, the conventional multi-resonance inverted-F antenna has problems in miniaturization, wide band, and gain deterioration. The present invention is a novel multi-resonant inverted F antenna that solves the above problems.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a main radiator of a plate-shaped conductor arranged so as to oppose a grounded plate-shaped conductor by a predetermined distance, and a feed line is a feeding point of the main radiator. A main radiator electrically connected to the main radiator, and a sub-radiator of a plate conductor disposed opposite to the grounded plate conductor by a predetermined distance from the main radiator. In the multi-resonance inverted-F antenna, the main radiator and the sub-radiator are multiple-resonance inverted-F antennas that are electrically connected to the grounded plate conductors, respectively.

[0006]

1 is a perspective view showing the basic construction of an embodiment of the present invention. The main radiator 2 is provided on the grounded conductor plate 1, and one end of the main radiator 2 is electrically connected to the ground conductor plate 1 via the short-circuit piece 3. Feeding point 4 of main radiator 2
Is connected to a power supply line 5, and the power supply line 5 is connected to a transceiver (not shown). On the upper part of the main radiator 2, the sub radiator 6
Is provided, and the short-circuit piece 7 is electrically connected to the ground conductor plate 1 separately from the short-circuit piece 3 from one end of the sub radiator 6. The main radiator 2 and the sub radiator 6 may be conductive ones, for example, copper is preferable. The ground conductor plate 1 is usually connected to the housing of the portable wireless device.

The spacing between the ground conductor plate 1, the main radiator 2 and the sub radiator 6 differs depending on the frequency used, and the resonance frequency is the size of the main radiator 2 and the sub radiator 6 and the main radiator 2. And the distance between the sub radiator 6 and the sub radiator 6. FIG. 2 shows the actual measurement of antenna return loss when the sizes of the main radiator 2 and the sub radiator 6 are 25 mm × 25 mm, 10 mm × 15 mm, and the distance between the main radiator 2 and the sub radiator 6 is 5 mm. Indicates a value. As can be seen from FIG. 2, point A (1.41 GHz) and point B (1.
46 GHz) has a low return loss, that is, there are two resonance frequencies.

FIG. 3 is a Smith chart showing the characteristic impedance of the multi-resonance inverted F antenna of this embodiment, and FIG. 4 is its measured gain characteristic diagram. In FIG. 4, the characteristic D shows the gain characteristic of the dipole antenna, and the characteristic C shows the gain characteristic of the present invention. As can be seen from the gain characteristic diagram of FIG. 4, the multi-resonance inverted-F antenna according to the present invention causes a maximum gain reduction of 2 dB in the band of 1.38 GHz to 1.46 GHz (80 MHz) as compared with the dipole antenna.

As an embodiment of the present invention, the case where a single sub-radiator is provided has been described, but the same effect can be obtained when a plurality of sub-radiators are multi-layered. It is possible to obtain sub-resonant frequencies corresponding to the number of It is also possible to construct the main radiator in a sandwich form with a plurality of sub-radiators in multiple layers.

[0010]

As described above, according to the present invention,
Since the main radiator and the sub-radiator are connected to the ground conductor plate separately, the multi-resonance inverted F antenna with wide band and less gain deterioration in the operating frequency band while keeping the antenna shape small. Can be realized.

[Brief description of drawings]

FIG. 1 is a perspective view showing a basic configuration of a multi-resonance inverted F antenna according to an embodiment of the present invention.

FIG. 2 is an antenna return loss characteristic of the multi-resonance inverted F antenna according to the embodiment shown in FIG.

FIG. 3 is a characteristic impedance diagram on the Smith chart of the multi-resonance inverted F antenna according to the embodiment shown in FIG.

4 is a gain characteristic of the multi-resonance inverted F antenna according to the embodiment shown in FIG.

[Explanation of symbols]

 1 Grounding conductor plate 2 Main radiator 3 Short-circuit piece 4 Feed point 5 Feed line 6 Sub-radiator 7 Short-circuit piece

Claims (2)

[Claims] 1. A main radiator of a plate conductor arranged to oppose a grounded plate conductor by a predetermined distance, wherein a feed line is electrically connected to a feeding point of the main radiator. In a multi-resonance inverted-F antenna composed of a main radiator and a sub-radiator of a plate-shaped conductor arranged opposite to the grounded plate-shaped conductor by a predetermined distance from the main radiator, The multi-resonance inverted F antenna, wherein the main radiator and the sub radiator are electrically connected to the grounded plate-shaped conductor separately. 2. The multi-resonance inverted F antenna according to claim 1, wherein the sub-radiators are arranged in a plurality of layers with a predetermined distance maintained therebetween.