JP2005079831A - Antenna circuit and antenna system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna circuit and an antenna system where machine parts of for general purposes can be utilized and with which stable reception is always possible even in the case of intense electric field and a transmission distance is improved by reducing suppression by the interfering wave of a near frequency. <P>SOLUTION: The antenna circuit is provided with a receiving circuit part connected to an antenna 1 for receiving radio waves of a microwave band. The receiving circuit part comprises: a low-noise amplifying circuit 3 which amplifies a received signal; and a bandpass filter 2 which transmits a desired frequency. The bandpass filter 2 is arranged between the antenna 1 and the low-noise amplifying circuit 3, and connected directly to the antenna 1 with a connector C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an antenna circuit and an antenna device that are effective as a technique for reducing the influence of a strong electric field at a nearby frequency, particularly when transmitting / receiving microwave radio waves.

  In an antenna circuit that receives weak radio waves of about −100 dB or less, such as radio waves from a communication satellite or the like in a microwave band or a quasi-microwave band, the signal received by the antenna is amplified by an amplifier circuit, and then a dielectric filter A signal having a target frequency is obtained through a band-pass filter composed of the like.

  In such an antenna circuit, there is a problem that a suppression level due to an interference wave of a nearby frequency is large, and stable reception is difficult in a strong electric field region.

  As a countermeasure against this point, an antenna circuit technique disclosed in Patent Document 1 is known. This antenna circuit inserts a bandpass filter that passes the target frequency at a position immediately after the antenna between the antenna that receives radio waves in the microwave band and quasi-microwave band and the low-noise amplifier circuit that amplifies the received signal. Connected.

As a result, compared to the case where a band-pass filter is inserted after the amplifier circuit, suppression by interference waves in the vicinity of the frequency is reduced, relatively stable reception is possible even in strong electric fields, and a low-noise amplifier circuit is used. Therefore, there is an advantage that the noise figure can be suppressed even if a band pass filter is inserted immediately after the antenna.
By the way, in this type of antenna circuit, the antenna and the band-pass filter or the antenna and the amplifier circuit are often connected by a coaxial cable. For example, a transmission distance in a wireless image transmission system using this coaxial cable and having a use frequency of 2.4 GHz and a transmission power of 10 mW / MHz is 1 to 3 Km, and stable reception cannot be obtained beyond that.

  The inventors of the present application have studied various measures for improving the transmission distance in this wireless image transmission system that does not require a radio operator license, and as a result of repeated experiments, the main cause is the coaxial cable used in the antenna circuit. I found out. That is, although this coaxial cable has a shield layer, it has been found that the ability to shield external noise is not sufficient depending on the frequency band used, and the influence is particularly remarkable in a strong electric field region.

  An object of the present invention is to provide a general-purpose equipment that can be used, an antenna capable of reducing the suppression by interference waves in the vicinity of the frequency, enabling stable reception even in a strong electric field, and greatly improving the transmission distance. An object is to provide a circuit and an antenna device.

An antenna circuit of the present invention includes a receiving circuit unit connected to an antenna that receives microwave waves, and the receiving circuit unit includes a low-noise amplifier circuit that amplifies a received signal, and a band-pass filter that passes a target frequency. The band-pass filter is arranged between the antenna and the low-noise amplifier circuit and is directly connected to the antenna by a connector.

  According to the present invention, the connection of the band-pass filter to the antenna is directly connected by a connector without using a coaxial cable, so that it is possible to eliminate the cause of being easily disturbed by a strong electric field at a nearby frequency. it can. As a result, suppression by interference waves in the near frequency is remarkably reduced, stable reception is always possible even with a strong electric field, and the transmission distance can be significantly improved. In addition, since a commercially available connector can be adopted, the antenna circuit can be configured using general-purpose equipment as a whole.

  The antenna circuit of the present invention includes a receiving circuit unit connected to an antenna that receives microwave radio waves and a transmitting circuit unit connected to the antenna, and the receiving circuit unit amplifies the received signal of the antenna. And a band-pass filter that passes the target frequency, and the band-pass filter is disposed between the antenna and the low-noise amplifier circuit and is directly connected to the antenna by a connector; did.

  According to this antenna circuit, in addition to the above-described effects, it can be used as an antenna circuit for transmission and reception.

  Here, it is desirable that the bandpass filter and the low noise amplifier circuit are directly connected by a connector. By doing so, it is possible to eliminate the cause of strong electric field interference in the vicinity of the frequency as in the case of the connector connecting the antenna and the bandpass filter.

  The connector is preferably made of metal and includes a jack-to-jack combination. This is because commercially available antennas, band-pass filters, and terminals on the low-noise amplifier circuit side are often plugs, and can easily cope with replacement or change of these equipments.

  It is desirable that an attenuator for matching with the receiver is connected immediately after the low noise amplifier circuit. As described above, when an attenuator for matching with the receiver is connected immediately after the low noise amplifier circuit, the stability of the reception state can be further improved.

  The antenna is a planar antenna, and the connector, the bandpass filter, the low-noise amplifier circuit, and the attenuator are preferably arranged on a uniaxial extension orthogonal to the planar antenna. If arranged in this way, attenuation in the coaxial is reduced, so not only weak radio waves can be received stably, but the surrounding strong electric field is not mixed in as much as possible by arranging the circuit system linearly. It can be configured.

  It is desirable that a switching circuit for switching between the receiving circuit unit and the transmitting circuit unit is connected immediately after the band pass filter. By connecting the switching circuit immediately after the band-pass filter, the configuration in which the antenna and the band-pass filter are directly connected by the connector can be realized without changing.

  In the antenna device of the present invention, at least the receiving circuit unit and the antenna of the receiving circuit unit and the transmitting circuit unit are accommodated in the case, and the case is provided with a mounting part for attaching a tripod for maintaining the posture of the case. It can be configured. By providing a tripod mounting portion on the case, it is possible not only to use a commercially available tripod as it is, but also to easily carry and move the antenna device.

Since the antenna circuit of the present invention adopts a configuration in which a connector is directly connected instead of a coaxial cable, suppression by interference waves in the vicinity frequency is reduced, stable reception is always possible even in a strong electric field, and a transmission distance is also increased. It can be improved dramatically and general-purpose equipment can be used. Further, in the antenna device of the present invention, by providing a tripod mounting portion on the case, not only a commercially available tripod can be used as it is, but also the antenna device can be easily carried and moved.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

(First embodiment)
FIGS. 1-8 is a figure which shows the antenna circuit and antenna apparatus which concern on the 1st Embodiment of this invention. In these drawings, FIG. 1 is a configuration diagram of an antenna circuit, and FIG. 2 is a component layout diagram thereof. 3 to 7 show specific configuration diagrams of an antenna apparatus employing the antenna circuit. FIG. 8 is a diagram showing experimental results.

  As shown in FIG. 1, the antenna circuit according to this embodiment includes an antenna 1 that receives a microwave band radio wave, and a receiving circuit unit connected to the antenna 1. The receiving circuit unit includes a low noise amplifying circuit 3 for amplifying a received signal, a bandpass filter 2 for passing a target frequency, and an attenuator (attenuator) 4 connected for the purpose of matching with the receiver.

  The band-pass filter 2 is disposed between the antenna 1 and the low noise amplifier circuit 3 and is directly connected to the antenna 1 by a connector C shown in FIG. Further, the band pass filter 2 and the low noise amplifier circuit 3 are also directly connected by the connector C.

  FIG. 3 shows an external view of the antenna device. As shown in FIGS. 3 and 2, the antenna 1 is a planar antenna and serves as a lid of a case 5 that houses an antenna circuit. The case 5 has a substantially rectangular box shape, and an antenna circuit is accommodated therein. One end side of the case 5 is open, and the antenna 1 covers the open portion.

  The case 5 includes a case main body 54 having a plurality of (four) frames 51, a bottom plate 52 fixed to the frame 51, a back plate 53 fixed to one end side of the frame 51, and a detachable covering the case main body 54. And a cover 55. The cover 55 is formed in an inverted U shape having a top plate 56 and left and right side plates 57.

  As shown in FIG. 4, the antenna 1 is provided with a plug 11 as a terminal and protrudes from the inner surface of the antenna 1 into the case 5. On the bottom plate 52 of the case 5, the band pass filter 2 is fixed with screws 6, and the low noise amplifier circuit 3 is fixed at the subsequent stage.

  The connector C is made of metal and includes a connection between the jack and the jack. This is because the commercially available antenna 1, the bandpass filter 2, and the terminals on the low-noise amplifier circuit 3 side are often plugs, so that these equipments (parts) can be easily replaced or changed. It is.

  In this embodiment, the connector C is a combination of a so-called jack-to-jack (female connector) 10 having jacks at both ends and plugs (male connectors) 11, 21, 22, 31 provided on each component. The method of combining with each other is adopted. That is, the antenna 1, the band pass filter 2, and the low noise amplifying circuit 3 are connected linearly using two jacks to jacks.

Specifically, the plug 11 of the antenna 1 and the plug 21 on the input side of the band pass filter 2 are directly connected by a jack-to-jack (female connector) 10. Further, the output-side plug 22 of the band-pass filter 2 and the input-side plug 31 of the low-noise attenuator 3 are directly connected by a jack-to-jack (female connector) 10.

  By connecting the parts linearly in this way, the surrounding strong electric field is prevented from being mixed as much as possible, and the connection length of the connector part can be shortened by using a connector such as a jack-to-jack. It becomes possible.

  That is, the antenna 1 is a planar antenna, and a connector C, a bandpass filter 2, a low noise amplification circuit 3, and an attenuator 4 are arranged on a uniaxial extension orthogonal to the planar antenna. By arranging in this way, the attenuation in the coaxial is reduced and not only can weak radio waves be stably received, but the circuit system is arranged in a straight line so that surrounding strong electric fields are not mixed in as much as possible. It can be.

  Further, in this antenna device, at least the receiving circuit unit and the antenna 1 of the receiving circuit unit and the transmitting circuit unit are accommodated in the case 5, and the case 5 is for holding the posture of the case 5 as shown in FIG. A mounting portion 8 for attaching a tripod is provided. By providing the case 5 with the tripod mounting portion 8, it is possible not only to use a commercially available tripod as it is, but also to easily carry and move the antenna device.

  According to this embodiment, the band pass filter 2 is connected to the antenna 1 directly by the connector C without using a coaxial cable. Can be removed from. As a result, suppression by interference waves in the near frequency is remarkably reduced, stable reception is always possible even with a strong electric field, and the transmission distance can be significantly improved.

  In addition, since a commercially available connector can be adopted, the antenna circuit can be configured using general-purpose equipment as a whole. Furthermore, as shown in FIG. 3, the antenna device can be downsized as a whole.

  In addition, the transmission experiment result of the image image | photographed from the Tokyo bay coast sky using a helicopter was shown by the table form in FIG. The equipment standards used are as follows.

Bandpass filter: Passband 2.2 GHz to 2.6 GHz
: Cutoff attenuation -40dBm
Low noise preamplifier: Amplification width 400 MHz to 3 GHz
: Amplification amount 31dBm
Attenuator: Attenuation -3dBm
As can be understood from FIG. 8, the distance that can be normally received is improved to about 8 times that of the conventional type.

(Second Embodiment)
9 to 11 show a second embodiment of the present invention. FIG. 9 is a configuration diagram of the antenna circuit, and FIGS. 10 and 11 are configuration diagrams showing the component arrangement.

  The antenna circuit of this embodiment is different from the first embodiment in that a transmission circuit unit is provided in addition to the reception circuit unit. That is, as shown in FIG. 9, the antenna circuit includes a receiving circuit unit connected to the antenna 1 that receives a radio wave in the microwave band and a transmitting circuit unit connected to the antenna 1.

The reception circuit unit includes a low noise amplification circuit (reception amplifier) 3 that amplifies a reception signal of the antenna 1, a band pass filter 2 that passes a target frequency, and an attenuator 4, and the band pass filter 2 is connected to the antenna 1. It is arranged between the low-noise amplifier circuit 3 and is directly connected to the antenna 1 by a connector C.

  The transmission circuit unit includes an antenna 1, a band pass filter 2, a transmission amplifier 3a, and a variable attenuator 4a. The diode switching circuit 3b for switching to the reception amplifier 3 or the transmission amplifier 3a and switching to the reception circuit side attenuator 4 or the transmission circuit side variable attenuator 4a at the time of reception or transmission due to the provision of the transmission circuit unit. Has been inserted. Reference numeral 3c denotes an ALC (auto range controller) of the variable attenuator 4a. This is a combination of the variable attenuator 4a and the auto range controller 3c in order to supply the antenna 1 with the maximum output as the transmission side. 3d indicates a transmission / reception switcher.

  In the antenna circuit of this embodiment, as shown in FIGS. 10 and 11, a diode switching circuit 3b and a bandpass filter 2 are inserted immediately after the antenna 1 without using a coaxial cable. The band-pass filter 2 and the low-noise amplifier circuit (low-noise reception preamplifier) 3 are directly connected using the connector C as in the first embodiment.

  In addition, an antenna device equipped with this antenna circuit is equipped with a tripod mounting bolt hole (see FIG. 6) so that the entire antenna system can be stored in a case and mounted easily. A grip (not shown) can be attached so that it can be held in

  According to the antenna circuit of this embodiment, in addition to the function and effect of the first embodiment, it can be used as a transmission / reception antenna circuit, and in particular, the specified output on the transmission side can be sufficiently supplied to the antenna. Therefore, the image quality can be improved including the synergistic effect of both.

  In addition, the switching circuit 3b for switching between the receiving circuit unit and the transmitting circuit unit is connected immediately after the bandpass filter 2, so that the configuration in which the antenna 1 and the bandpass filter 2 are directly connected by the connector C is not changed. can do.

  The equipment standards used in this embodiment are exemplified below.

Bandpass filter: Passband 2.2 GHz to 2.6 GHz
: Cutoff attenuation -40dBm
Low noise preamplifier: Amplification width 400 MHz to 3 GHz
: Amplification amount 31dBm
Attenuator: Attenuation -3dBm
Transmitter amplifier: Maximum output 70mmW
: Minimum output 5mmW
Variable attenuator: Attenuation amount: -1 dBm to -6 dBm
It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

1 is a configuration diagram of an antenna circuit according to a first embodiment of the present invention. 1 is a component layout diagram of an antenna circuit according to a first embodiment of the present invention. 1 is an external view of an antenna device according to a first embodiment. It is an internal perspective view of the antenna device which concerns on 1st Embodiment. It is an internal perspective view of the antenna device which concerns on 1st Embodiment. It is a bottom view of the antenna apparatus which concerns on 1st Embodiment. It is the perspective view seen from the back of the antenna device concerning a 1st embodiment. It is a figure which shows the experimental result which concerns on 1st Embodiment. It is a block diagram of the antenna circuit which concerns on the 2nd Embodiment of this invention. It is a side view which shows the components arrangement | positioning of the antenna circuit of 2nd Embodiment. It is a top view which shows the components arrangement | positioning of the antenna circuit of 2nd Embodiment.

Explanation of symbols

1 Antenna (planar antenna)
2 Bandpass filter 3 Low noise amplifier (low noise receiving amplifier)
3a Transmission amplifier 3b Diode switching circuit 3c ALC (auto range controller)
4 Attenuator
4a Variable attenuator 5 Case 10 Female connector (jack to jack)
11, 21, 22, 31 Plug (male connector)
C connector

Claims (8)

A receiving circuit unit connected to an antenna for receiving microwave radio waves,
The receiver circuit unit includes a low noise amplifier circuit that amplifies a received signal, and a bandpass filter that passes a target frequency,
The antenna circuit, wherein the band pass filter is disposed between the antenna and the low noise amplifier circuit and is directly connected to the antenna by a connector. A receiving circuit unit connected to an antenna for receiving microwave radio waves, and a transmitting circuit unit connected to the antenna,
The reception circuit unit includes a low noise amplification circuit that amplifies a reception signal of the antenna, and a bandpass filter that passes a target frequency,
The antenna circuit, wherein the band pass filter is disposed between the antenna and the low noise amplifier circuit and is directly connected to the antenna by a connector.   The antenna circuit according to claim 1 or 2, wherein the band-pass filter and the low-noise amplifier circuit are directly connected by a connector.   4. The antenna circuit of claim 3, wherein the connector is made of metal and includes a jack-to-jack combination.   The antenna circuit according to claim 1, wherein an attenuator for matching with a receiver is connected immediately after the low-noise amplifier circuit.   The antenna is a planar antenna, and the connector, the band-pass filter, the low-noise amplifier circuit, and the attenuator are respectively disposed on a uniaxial extension orthogonal to the planar antenna. The antenna circuit described in 1.   The antenna circuit according to claim 2, wherein a switching circuit that switches between the reception circuit unit and the transmission circuit unit is connected immediately after the band-pass filter.   An antenna device, wherein at least a receiving circuit unit and an antenna of the receiving circuit unit and the transmitting circuit unit are accommodated in a case, and the case is provided with a mounting part for attaching a tripod for maintaining the posture of the case.

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