JP3501206B2 - Planar spiral antenna with driving reflector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar spiral antenna with a driving reflector.

[0002]

2. Description of the Related Art In recent years, mobile communication has been widely spread and used in society, and many systems including future multimedia communication services have been proposed. Frequency seems to be used. Therefore, an antenna used for such mobile communication is required to have wideband frequency characteristics that can be applied to a system using various frequencies. Spiral antenna
It is well known as an antenna with wideband frequency characteristics, and the details of its operating principle are described in "Antenna Engineering Handbook", pp.79-81, 1989, Ohmsha, Inc., edited by The Institute of Electronics, Information and Communication Engineers. , Here is a brief description.
FIG. 3 is a plan view illustrating a structural example of a conformal planar spiral antenna, and FIG. 4 is a perspective view illustrating a structural example of a conformal three-dimensional spiral antenna. The equiangular planar spiral antenna shown in Fig. 3 has two conductors 31 and 32 arranged on the same plane in a spiral pattern at an equal angle.
Since the 32 and non-conductor portions 31a and 32a are self-similar types that appear to be constant regardless of frequency, and the structure is determined by the spiral angle instead of the conductor length, the antenna characteristics are constant regardless of frequency. Wideband frequency characteristics are realized. Since the planar spiral antenna is usually constructed by using a dielectric substrate, it has an advantage that it can be easily mass-produced by the photo edging technique. However, since it has a radiation directivity that radiates energy to both surfaces of the dielectric substrate due to its planar structure, the radiant energy is more easily dispersed as compared with a three-dimensional spiral antenna described later, and therefore,
There is a drawback that the antenna gain is low. The gain of an actual planar conformal spiral antenna is the same as that of a dipole antenna.
It is known to be about 2 dBi.

On the other hand, the conformal three-dimensional spiral antenna shown in FIG. 4 was devised to improve the radiation directivity of the above-mentioned conformal planar spiral antenna.
The two spiral conductors 34 and 35 are arranged in a self-similar form like the above-mentioned equiangular planar spiral antenna, and the currents excited on the conductors 34 and 35 are three-dimensionally distributed from the zenith. Therefore, the operating principle is the same as that of the planar spiral antenna described above, so it has a wide-band frequency characteristic, and due to the three-dimensional excitation current distribution, a single radiation direction similar to that of a helical antenna is formed in the direction perpendicular to the conical zenith to the bottom surface. The radiated energy is concentrated in one direction and the antenna gain is higher than that of the planar spiral antenna. However, since it has a three-dimensional structure, it has drawbacks that it is not easy to manufacture and mass production is difficult. Therefore, in order to improve the antenna gain by making the radiation directivity of the above-mentioned planar spiral antenna suitable for mass production into a single characteristic, a planar spiral antenna with a reflector having a metal reflector under the dielectric substrate has been proposed. ing. FIG. 5 is a perspective view showing a structural example of an equiangular planar spiral antenna with a reflector. The equiangular planar spiral antenna with a reflector shown in this example, like the antenna shown in FIG. 3, spirals two conductors 42 and 43 on the dielectric substrate 41 at an equal angle so as to form a self-similar shape (spiral). Arranged in a shape. Further, a length h is provided behind the dielectric substrate 41.
The metal reflection plate 45 is arranged via the first dielectric spacer 44 of. Power supply to the antenna is balanced by a microstrip line from a coaxial connector 47 attached to the housing 46.
/ By connecting to the center points of the spiral conductors 42, 43 via the unbalance conversion unit 48, the metal reflection plate 45 is held on the housing 46 by the second dielectric spacer 49. Here, specific dimensions of the spiral conductors 42, 43 or the balanced / unbalanced conversion unit 48 for matching the balanced spiral antenna and the unbalanced coaxial line (coaxial connector) are described in the present invention. Details by authors, Takemura et al., "Consideration of conformal spiral in UHF band", IEICE, Material of Antenna and Propagation Research Group (Technical Report), scheduled to be announced on October 17th. Detailed description is omitted. In this planar spiral antenna with a reflector, the high-frequency power input to the connector 47 passes through the balanced / unbalanced conversion unit 48 and is a spiral conductor.
Power is supplied to the center points of 42 and 43 to excite the spiral antenna. If the distance between the dielectric substrate 41 on which the spiral conductors 42 and 43 are formed and the metal reflector 45 is set to h, the mirror image theory causes the two dielectric substrates 41 to be equivalently arranged at an interval of 2h. To do.

FIG. 6 shows measured values of gain characteristics of the planar spiral antenna with a reflector shown in FIG. However, the design frequency was set to 568 MHz (long λ) and h = 132 mm = λ / 4. From Fig. 6, in order to maximize the antenna gain of the planar spiral antenna with reflector, the dielectric substrate 41
It can be seen that the distance h between the metal reflection plate 45 and the metal reflection plate 45 may be set to λ / 4 of the design frequency or an odd multiple of λ / 4. That is, the design frequency of 568 MHz (h = λ / 4 = 0.25 λ), or
At 1700MHz (h = 0.75λ), the antenna gain is about 5dBi-10
It is maximized to dBi, improving the gain of 2 dBi of the above-mentioned planar spiral antenna without a reflector. It is considered that this is because the radio wave directly radiated from the spiral conductors 42 and 43 and the radio wave reflected by the metal reflection plate 45 are combined in the same phase. If the distance h between the dielectric substrate 41 and the metal reflection plate 45 is set to an even multiple of λ / 4, the radio wave directly radiated from the spiral conductors 42 and 43 and the radio wave reflected by the metal reflection plate 45 will be transmitted. Since and are likely to be combined in opposite phases,
The antenna gain is theoretically null. Actually, the gain characteristic shown in Fig. 6 has a frequency of 1200MHz (h = 0.5λ) or 2200
At MHz (h = 1 λ), the antenna gain drops below -10 dBi and deteriorates sharply.

[0005]

However, the above-described conventional planar spiral antenna with a reflector has the following problems. In other words, when it is necessary to operate the planar spiral antenna with reflector in a wide frequency bandwidth such as mobile communication in the future,
The distance h between the dielectric substrate on which the spiral conductor pattern is formed and the metal reflection plate changes from λ / 4 or an odd multiple of λ / 4 depending on the frequency used, and the antenna gain deteriorates. For example, according to the gain characteristics shown in Fig. 6, when the operating frequency is around 1200MHz or 2200MHz, the gain deteriorates sharply and communication becomes impossible. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems associated with the conventional planar spiral antenna with a reflector, and an object of the present invention is to provide a planar spiral antenna with a reflector that does not cause gain deterioration in a wide operating frequency range.

[0006]

In order to achieve the above object, the invention according to claim 1 of the planar spiral antenna with a driving reflector according to the present invention is a dielectric substrate having a spiral conductor pattern arranged on the surface thereof, and A spiral antenna comprising a metal reflector placed behind a dielectric substrate, wherein the spiral antenna varies depending on the frequency used.
The dielectric substrate and the metal reflection according to the wavelength λ
The distance to the plate is always λ / 4 or an odd multiple of λ / 4
Means for moving the position of said metal reflector
And the drive means is provided on the spiral antenna.
Drive based on frequency information from the connected transceiver
And a drive control unit for controlling the means.
It is a planar spiral antenna with a driving reflector. The invention according to claim 2 of the planar spiral antenna with a driving reflector according to the present invention is a spiral antenna comprising a dielectric substrate having a surface on which a spiral conductor pattern is arranged, and a metal reflecting plate arranged behind the dielectric substrate. there is, before
The spiral antenna is a wave that changes depending on the frequency used.
Between the dielectric substrate and the metal reflector depending on the length λ
The distance is always λ / 4 or an odd multiple of λ / 4
Drive means for moving the position of the dielectric substrate
The driving means is connected to the spiral antenna.
Based on the frequency information from the transceiver
A drive characterized by having a drive control unit for controlling
It is a planar spiral antenna with a dynamic reflector.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on the illustrated embodiments. FIG. 1 is a structural cross-sectional view showing an embodiment of a flat spiral antenna with a driving reflector according to the present invention. The planar spiral antenna 20 with a driving reflector shown in this example has spiral conductors 1 and 2
Via the dielectric substrate 3 disposed on the upper surface, the metal reflector 4 disposed behind the dielectric substrate 3 with a distance h, and the through holes 5 provided at the four corners of the metal reflector 4. A dielectric spacer 6 for supporting the dielectric substrate 3, a rack 7 fixed to the metal reflection plate 4, and a rack 7 mounted on the drive shaft 8a.
Via the step motor 8 having the pinion 9 fitted to the motor, the motor placement table 11 for installing the step motor 8 placed on the housing 10, and the through hole 3a provided in the dielectric substrate 3 to the spiral conductor. Balanced line 12 connected to 1 and 2, and coaxial line (unbalanced line) 13 connected to transceiver 21 described later.
And a balun 14 for matching the balanced line 12 and the coaxial line (unbalanced line) 13. The balun 14 may be replaced by the balanced / unbalanced conversion unit 48 shown in FIG.

FIG. 2 is a functional block diagram for explaining an operation example of the planar spiral antenna with a driving reflector according to the present invention. The functional block diagram shown in this example is a planar spiral antenna 20 with a driving reflector, a transceiver 21 that inputs and outputs an RF signal 20a and is connected to the planar spiral antenna 20 with a driving reflector, and frequency information from the transceiver 21. A signal 21a is input and a reflector drive position information signal 22a is output to the planar spiral antenna 20 with a drive reflector, and a reflector drive controller 22 is provided. The operation of the planar spiral antenna with a driving reflector shown in FIG. 1 will be described in detail below with reference to FIG. When the plane spiral antenna 20 with a driving reflector according to the present invention receives an incoming signal 23, it transmits it to the transceiver 21 as an RF signal 20a. The transceiver 21 demodulates the RF signal 20a and
When the frequency component of a is detected and the detected frequency information is sent to the reflector drive control unit 22 as a frequency information signal 21a,
The reflector drive control unit 22 calculates the distance of λ / 4 at the wavelength λ of the frequency currently used based on the frequency information signal 21a, and uses this as the reflector drive position information signal 22a to drive the planar spiral antenna 20 with a reflector. Send to. Then, in the planar spiral antenna 20 with a driving reflector, when the step motor 8 gives a predetermined rotation to the drive shaft 8a based on the reflector driving position information signal 22a, the pinion 9 attached to the drive shaft 8a rotates, so the pinion. The rack 7 fitted in 9 moves up and down by the rack-and-pinion system, and the metal reflection plate 4 moves by a predetermined distance so that the distance h between the dielectric substrate 3 and the metal reflection plate 4 becomes λ / 4.

Since the planar spiral antenna 20 with a driving reflector according to the present invention operates as described above, the dielectric substrate 3 and the metal reflector are automatically detected even if the frequency used changes. Since the metal reflector 4 can be controlled so that the distance h to 4 is always λ / 4 at the used frequency, the antenna gain can be kept at the maximum (maximum) regardless of the used frequency. Above, dielectric substrate
Although the example in which the distance h between the metal plate 3 and the metal reflector 4 is set to λ / 4 has been described, the distance h is set to λ as described in the prior art.
Even if it is set to an odd multiple of / 4, the same effect as λ / 4 can be obtained, so the position of the metal reflector 4 may be controlled so that the distance h becomes an odd multiple of λ / 4. .

In the above description, an example in which the incoming signal 23 is received has been described. However, when the RF signal is transmitted from the transceiver 21, the frequency used is known, so this frequency information is used as the frequency information signal 21a. Reflector drive controller 22
As in the case of the above-mentioned reception, the position of the metal reflector 4 can be controlled so that the distance h 1 becomes λ / 4 of the used frequency or an odd multiple of λ / 4. In addition, in the embodiment of the present invention described above, the metal reflector 4 is driven. However, the present invention is not limited to this example. For example, the dielectric spacer 6 is described above. The position of the dielectric substrate 3 may be controlled by being driven by a driving unit or the like.

[0011]

As described above, according to the present invention, the distance h between the dielectric substrate on which the spiral conductor is arranged and the metal reflector is λ / 4 for each used frequency (wavelength λ) or an odd multiple of λ / 4. Since the position of the metal reflector is changed so as to achieve the above, it is effective in realizing a planar spiral antenna with a reflector without gain deterioration in a wide operating frequency range.

[Brief description of drawings]

FIG. 1 is a structural cross-sectional view illustrating an embodiment of a flat spiral antenna with a driving reflector according to the present invention.

FIG. 2 is a functional block diagram for explaining an operation example of the planar spiral antenna with a driving reflector according to the present invention.

FIG. 3 is a plan view illustrating a structural example of a conventional equiangular planar spiral antenna.

FIG. 4 is a perspective view illustrating a structural example of a conventional conformal three-dimensional spiral antenna.

FIG. 5 is a perspective view illustrating a structural example of a conventional planar spiral antenna with a reflector.

FIG. 6 is a diagram showing a gain characteristic of a conventional planar spiral antenna with a reflector.

[Explanation of symbols]

1, 2 ... Swirl (spiral) conductor, 3 ... Dielectric substrate,
3a ... Through holes provided in the dielectric substrate, 4 ... Metal reflector,
5 ・ ・ Through hole on metal reflector, 6 ・ ・ Dielectric spacer, 7 ・ ・ Rack, 8 ・ ・ Step motor, 8a ・ ・ Step motor drive shaft, 9 ・ ・ Pinion, 10 ・ ・ Housing, 11
..Motor placement stand, 12 ... Balanced line, 13 ... Coaxial line (unbalanced line), 14 ... Balan, 20 ... Flat spiral antenna with driving reflector, 20a ... RF signal, 21 ... Transceiver,
21a ... Frequency information signal, 22 ... Reflector drive control unit,
22a..Reflector drive position information signal, 23..arrival signal

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Teruo Onishi Inventor Teruo Onishi 2-1-1 Kotani, Samukawa-cho, Takaza-gun, Kanagawa Toyo Communication Equipment Co., Ltd. (72) Yukio Naito 2-chome, Otani, Samukawa-cho, Takaza-gun, Kanagawa Prefecture No. 1 Toyo Communication Equipment Co., Ltd. (56) Reference JP-A-6-181408 (JP, A) JP-A-9-162632 (JP, A) JP-A-9-270630 (JP, A) JP-A 53-5947 (JP, A) Actual development 60-22009 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01Q 9/00-11/20 H01Q 19/10

Claims (2)

(57) [Claims] 1. A spiral antenna comprising a dielectric substrate having a surface on which a spiral conductor pattern is arranged, and a metal reflecting plate arranged behind the dielectric substrate, wherein the spiral antenna changes depending on a frequency used.
Depending on the wavelength λ, the dielectric substrate and the metal reflector
The spacing should always be λ / 4 or an odd multiple of λ / 4
A driving means for moving the position of the metal reflector;
And the drive means is connected to the spiral antenna
Controls the drive means based on frequency information from the transceiver
Drive control section for
Planar spiral antenna with firing plate. 2. A spiral antenna comprising a dielectric substrate having a surface on which a spiral conductor pattern is arranged, and a metal reflecting plate arranged behind the dielectric substrate, wherein the spiral antenna changes depending on a frequency used.
Depending on the wavelength λ, the dielectric substrate and the metal reflector
The spacing should always be λ / 4 or an odd multiple of λ / 4
Drive means for moving the position of the dielectric substrate
And the drive means is connected to the spiral antenna
Controls the drive means based on frequency information from the transceiver
Drive control section for
Planar spiral antenna with firing plate.