JP2019047415A - Antenna device - Google Patents

Abstract

The present invention provides an antenna device which can be miniaturized and which can be easily reduced in cost.
SOLUTION: A narrow band antenna which resonates only at a frequency width in which an FM wave band is subdivided by an inductance (L1 to L4) and a capacitance (C0 to C4) cut at each tap from a metal element 40 and a coil element L Configure. The control circuit 90 changes the magnitude of the reactance loaded on the metal element 40 in accordance with the tuning information input from the vehicle-side receiver, thereby enabling reception of the entire FM wave band. The control circuit 90 also enables demodulation of a signal of a frequency that can be received by the narrow band antenna by controlling the demodulation circuit 80. Thus, the metal element 40 is miniaturized, and the circuit configuration of the demodulation circuit 80 is also simplified.
[Selected figure] Figure 5

Description

  The present invention relates to an antenna device using a narrow band antenna.

  As an AM / FM shared antenna device mounted on a vehicle, an on-vehicle antenna device disclosed in Patent Documents 1 and 2 is known. In the on-vehicle antenna device disclosed in Patent Document 1, an antenna substrate on which an antenna pattern for FM broadcast reception is formed is erected on a flat antenna base, and is straddled above the antenna substrate. A roof-like top for AM / FM broadcast reception is arranged.

Further, in the on-vehicle antenna device disclosed in Patent Document 2, the circuit board is disposed below the radome (antenna case), and the first antenna element (for AM broadcast reception) is disposed above the radome. . In addition, the second antenna element (for AM / FM broadcast reception) is disposed outside the center in the radome, and the first antenna element, the second antenna element, and the circuit board draw a U-shape. Such an arrangement is said to be smaller than the on-vehicle antenna device disclosed in Patent Document 1.

Unexamined-Japanese-Patent No. 2010-21856 JP, 2013-110601, A

The antenna apparatuses disclosed in Patent Documents 1 and 2 are both wide-band antennas capable of receiving the entire area of the FM wave band, and therefore are provided with planar elements having a large area. Therefore, there is a limit to the miniaturization of the device.
In addition, in the on-vehicle antenna device disclosed in Patent Document 1 and many AM / FM shared antenna devices equipped with an amplifier circuit, the received signal is split into a signal in the AM waveband and a signal in the FM waveband. After amplifying each signal, both signals are combined and transmitted to the vehicle receiver. Therefore, a splitter and a coupler become indispensable, and not only the structure of the device becomes complicated, but there is also a problem that the signal level is lowered due to the branching loss and the coupling loss.

  Focusing on the fact that a specific broadcast frequency is assigned to the FM broadcast station, it is sufficient if the user can receive and demodulate only the frequency at which the broadcast is listened, and by implementing such an antenna device Can be simplified and further miniaturized.

  The main object of the present invention is to provide an antenna device which can be further miniaturized and whose cost can be easily reduced.

  According to the present invention, a rod-shaped or strip-shaped metal element capable of receiving a signal of a frequency width obtained by dividing a predetermined frequency band by loading a reactance, reactance loading means for loading the reactance to the metal element, and A control means for receiving input of tuning information representing the selected frequency and changing the magnitude of the reactance to be loaded by the reactance loading means according to the input tuning information; I will provide a.

  According to the antenna device of the present invention, the narrow band antenna can be configured by the metal element capable of receiving the signal of the frequency width obtained by dividing the frequency band (broadcast frequency band) and the reactance loading means. Even if it is a narrow band antenna, the signal of the broadcast frequency represented by the channel selection information can be received by changing the magnitude of the reactance to be loaded, so it is not necessary to use a wide band antenna which does not subdivide the broadcast frequency band. Therefore, the antenna device can be further miniaturized.

(A)-(c) is an external view of the antenna apparatus of 1st Embodiment. The top view which shows the structural example of the antenna base with which the antenna apparatus of 1st Embodiment is provided. (A) is a side view of the antenna apparatus of 1st Embodiment of the state which removed the antenna case, (b) is a front view. (A), (b) is a figure which shows the modification of FIG. 3 (a), (b). BRIEF DESCRIPTION OF THE DRAWINGS The whole block diagram of the antenna apparatus of 1st Embodiment. Explanatory drawing of the FM wave band received by the antenna apparatus of 1st Embodiment. Explanatory drawing of the frequency width of the FM wave band which can be adjusted with the antenna apparatus of 1st Embodiment. The illustration figure of the switch table which a control circuit has. The timing chart of the control signal output from a control circuit. The characteristic view which shows the frequency of FM wave band, and the relation of average gain. The characteristic view which shows the relationship between the frequency of AM wave band, and an output voltage level. (A) is a side view of the antenna apparatus of 2nd Embodiment in the state which removed the antenna case, (b) is a front view.

  The following will describe an embodiment of the present invention applied to an on-vehicle antenna device for receiving signals in the AM wave band (522 kHz to 1710 kHz) and the FM wave band (76 MHz to 95 MHz or 87.5 MHz to 108 MHz). . The antenna device is attached to, for example, a vehicle roof, and is electrically connected to a vehicle receiver mounted in the vehicle via a communication cable or the like.

  In the following description, the vehicle roof side is "down" direction, vertically upward from the vehicle roof is "up" direction, the longitudinal direction is "back and forth" direction or "long direction", front is "front" and back is " The direction of 90 degrees with respect to the front longitudinal direction is called "rightward", and the opposite direction is called "leftward". The relatively front part is called "front" and the rear part is called "rear". Also, the “upper and lower” directions may be expressed as “front and back”, or expressions similar to those may be used, but they are synonymous.

First Embodiment
Fig.1 (a) is a side view of the antenna apparatus 1 which concerns on 1st Embodiment, (b) is a top view, (c) is a rear view. The antenna device 1 includes an antenna case 10 and an antenna base 20. The antenna case 10 is formed of a radio wave transmitting member, and a storage space is formed inside. The antenna case 10 is formed in a streamlined shape that rises from the front to the rear of the mounting surface. This is to reduce air resistance after mounting. The antenna base 20 is provided with a mounting mechanism 23 for fixing the mounting surface of the vehicle roof. In the central portion of the attachment mechanism 23, a hole is formed to allow the communication cable to penetrate. The height from the attachment surface to the highest portion of the antenna case 10 is about 65 mm or less.

  FIG. 2 is a top view showing an exemplary structure of the antenna base 20. As shown in FIG. The antenna base 20 includes a conductive base 21 attached to the mounting portion and an insulating base 22 supported by the conductive base 21. The mounting mechanism 23 is fixed at substantially the center of the conductive base 21. The peripheral portion of the insulating base 22 is airtightly fitted with the antenna case 10. The length in the longitudinal direction of the insulating base 22 is about 110 mm and the width is about 40 mm.

  Various antenna components are mounted on the antenna base 20. FIG. 3 (a) is a side view showing an example of mounting of the antenna component with the antenna case 10 removed, and FIG. 3 (b) is a front view. On the upper surface of the antenna base 20, a unit housing 30 fixed detachably by screwing or the like is provided. The unit housing 30 is formed in a box shape having an upper bottom and a lower bottom smaller than the opening surface of the antenna case 10, and a plurality of circuit units as an example of antenna components are accommodated in the unit housing 30, respectively. Ru. Further, support rods 32 and 34 made of resin are provided upright from the upper surface of the unit housing 30 in the vicinity of the end in the front-rear direction (longitudinal direction) facing each other. Each support rod 32, 34 supports the metal element 40 at its upper end and supports the coil element L at its side.

  The metal element 40 has a ground potential surface, that is, a surface facing the vehicle roof which is the conductive base 21 or the mounting surface, and the left and right side portions 40a and 40b are viewed downward from the rear in parallel with the ground potential. It is a band-shaped element having a U-shaped cross section (a shape without one side of a square) which is bent. The side portions 40a and 40b are provided to increase the radiation resistance and to increase the antenna gain. The metal element 40 does not necessarily have to be in the shape of a band, and may be in the shape of a rod.

  The metal element 40 is a copper plate having a thickness of about 0.5 mm, a width of about 5 mm, a length of a bent portion of about 5 mm, and a length of about 95 mm in the front-rear direction (long direction). However, the material may be stainless steel or another conductor plate.

  The coil element L supported by the support rods 32 and 34 is wound at a predetermined pitch. The upper end of the coil element L is joined to a rod-like power feeding portion 41 provided substantially at the center of the metal element 40. The coil element L is also provided with four taps for each predetermined number of turns when viewed from the tip.

  The plurality of circuit units housed in the unit housing 30 are electrically connected to the vehicle-side receiver via a communication cable or the like installed via the hole of the attachment mechanism 23. The circuit units may be arranged in a line in the front-rear direction of the antenna base 20. In this way, the width of the antenna base 20 is also reduced, and the antenna device 1 can be thinned.

  The support rods 32, 34 and the unit housing 30 are not limited to the examples shown in FIGS. 3 (a) and 3 (b). For example, the side view of FIG. The structure and arrangement shown in the front view of FIG. That is, the support rods 32 and 34 may be fixed to the upper surface of the antenna base 20, and the unit housing 30 'may be detachably fixed to the back surface side of the antenna base 20 with the vehicle roof 300 interposed therebetween. In this case, the attachment mechanism 23 or the corresponding mechanism is attached to the contact portion between the unit housing 30 ′ and the vehicle roof 300.

With such a structure and arrangement relation, there is an advantage that the restrictions on the arrangement, size, mounting form and the like of the plurality of circuit units accommodated in the unit housing 30 ′ are eliminated. In addition, since the number of antenna components above the vehicle roof 30 is reduced, there is an advantage that further downsizing can be achieved. Furthermore, since the plurality of circuit units are disposed inside the vehicle, the heat resistance is also improved.
The unit housing 30 and the unit housing 30 ′ may be used in combination. That is, a plurality of circuit units may be distributed and disposed in two unit cases 30, 30 '. In this case, the same advantages as described above are obtained as compared with the examples shown in FIGS. 3A and 3B in which a plurality of circuit units are arranged only in the unit housing 30.

  FIG. 5: is a figure which shows the example of a connection structure of the antenna components containing each circuit unit which the antenna apparatus 1 of 1st Embodiment has. In the first embodiment, an example in which the switching circuit 50, the serial / parallel converter 60, the booster amplifier 70, the demodulation circuit 80, and the control circuit 90 are used as circuit units housed in the unit housing 30 (30 ') is described. explain.

As described above, the coil element L is provided with four taps. These taps are connected to input terminals 501 to 505 of the switching circuit 50 together with the base end of the coil element L. The inductance from the tip of the coil element L (the feeding portion 41 of the metal element 40) is the input terminal 501 (L1), the input terminal 502 (L1 + L2), the input terminal 503 (Σ (L1 to L3)), the input terminal 504 (Σ (L1 to L4), and the input terminal 505 (Σ (L1 to L5)) increases in the order. The input terminal 505 is connected to the AM output terminal 507.
In the first embodiment, the narrow band antenna for FM broadcast reception is configured by the inductances (L1 to ((L1 to L4)) extracted through the respective taps of the coil element L and the metal element 40. The metal element 40 and the full length (全長 (L1 to L5)) of the coil element L constitute an antenna for AM broadcast reception.

  The switching circuit 50 constitutes a reactance loading means together with the coil element L. Specifically, the zone selection unit (first reactance unit) 51 that outputs the coarse adjustment reactance of the resonance frequency of the metal element 40, and the tuning selection unit (second reactance unit) that outputs the fine adjustment reactance of the resonance frequency And 52, to constitute a reactance loading means. The input terminals 501 to 504 are connected to the input side of the zone selection unit 51, and the output side of the zone selection unit 51 of the input terminals 501 to 504 is connected to the tuning selection unit 52. That is, the zone selection unit 51 and the tuning selection unit 52 are connected in series. The tuning selection unit 52 is connected to the FM output terminal 508.

  The zone selection unit 51 is connected to the switching element Z1 which turns on (closed) or off (opens) the connection with the input terminal 501, and the connection with the switching element Z2 which turns on or off the connection with the input terminal 502 A switching element Z3 for turning on or off and a switching element Z4 for turning on or off the connection with the input terminal 504 are connected in parallel. When the zone selection unit 51 receives an FM wave band signal, any one of the switching elements Z1 to Z4 is turned on, and the others are turned off. As a result, the inductors L1 to L4 exhibit an inductance. The zone selection unit 51 outputs a coarse adjustment reactance, which is an inductance in this example.

The tuning selection unit 52 includes a circuit of only the capacitor C0, a series circuit of a capacitor C1 and a switching element T1, a series circuit of a capacitor C2 and a switching element T2, a series circuit of a capacitor C3 and a switching element T3, and a capacitor C4. And a series circuit of the switching element T4 are connected in parallel. The tuning selection unit 52 outputs a reactance for fine adjustment, in this example, a capacitance. Each of the capacitors C0 to C4 exhibits a capacitance value satisfying a resonance condition with the inductors L1 to L4, but also functions as a capacitor for cutting a direct current.
The fine adjustment capacitance is added to the coarse adjustment inductance. As a result, the signal of the FM waveband that can be received can be output from the FM output terminal 508.

  FIG. 6 shows a frequency-average gain characteristic diagram of an FM wave band received by the antenna device 1 of the first embodiment. In the example of FIG. 6, broadcast frequencies of 76 MHz, 79.5 MHz, 83 MHz, 86.5 MHz, and 90.0 MHz are shown, and the zone selection unit 51 performs coarse adjustment for resonating at these broadcast frequencies. The tuning selection unit 52 performs fine adjustment. As a result, in the antenna device 1 of the first embodiment, it is possible to shift the frequency to be resonated at a frequency width of 0.5 MHz as shown in FIG.

  In the case of receiving a signal in the AM wave band, all the switching elements Z1 to Z4 and T1 to T4 are turned off (opened). As a result, the AM wave band signal is received over the entire length (全長 (L1 to L5)) of the metal element 40 and the coil element L, and the FM wave band electricity is transmitted from the input terminal 505 of the switching circuit 50 to the AM output terminal 507. It is output independently of the constant (capacitors C0 to C4).

  The on (closed) and off (open) states of the switching elements Z1 to Z4 and T1 to T4 in the switching circuit 50 are controlled by switching data b0 to b7 output from the control circuit 90 via the serial parallel converter 60. Ru. The switching data b0 to b7 are generated based on tuning information indicating the selected broadcast frequency, which is sent from the vehicle receiver. This will be described later.

The booster amplifier 70 includes an AM signal amplifier circuit 71 electrically connected to the AM output terminal 507 and an FM signal amplifier circuit 72 electrically connected to the FM output terminal 508. A common AM / FM shared antenna device is provided with a splitter that divides the received signal into a signal in the AM waveband and a signal in the FM band, but in the antenna device 1 of the first embodiment, from the AM output terminal 507 The signal from the AM signal amplifier circuit 71 and the signal from the FM output terminal 508 are directly input to the FM signal amplifier circuit 72. Therefore, a branching filter is not required, and branching loss (signal level reduction) can be suppressed.
The signal of the AM wave band amplified by the AM signal amplifier circuit 71 and the signal of the FM wave band amplified by the FM signal amplifier circuit 72 are output to the demodulation circuit 80 without combining them. As a result, coupling loss (reduction in signal level) can also be suppressed.

The demodulation circuit 80 includes an AM tuner 81 that enables demodulation of an AM waveband signal and an FM tuner 82 that enables demodulation of an FM waveband signal. "Enable demodulation" refers to having the necessary functionality to demodulate a signal of a selected frequency. For example, tuning and detection of the broadcast frequency are also included in the function. The frequency at which demodulation by the FM tuner 82 is possible has a width, and the width is controlled by the control circuit 90. Specifically, the width of the frequency demodulated by the FM tuner 82 changes in synchronization with the control signal output to the switching circuit 50 via the serial parallel converter 60.
The AM waveband signal output from the AM tuner 81 and the FM waveband signal output from the FM tuner 82 are respectively demodulated into voice, music, etc. according to the channel selection information input from the vehicle receiver. It is output to the vehicle receiver.

  The AM tuner 81 and the FM tuner 82 are so-called electronic tuners, and can be realized by firmware as part of a control circuit 90 described later. That is, by specifying a frequency to be demodulated, it is possible to realize by software installed in firmware.

  The control circuit 90 controls the switching circuit 50 and the demodulation circuit 80 according to the channel selection information input from the vehicle-side receiver. For example, when receiving a signal in the AM wave band, all the switching elements Z1 to Z4 and T1 to T4 of the zone selection unit 51 and the tuning selection unit 52 are turned off, and the FM tuner 82 is turned off. When the FM wave band is received, the magnitude of the reactance is controlled by the zone selection unit 51 and the tuning selection unit 52, and the width of the frequency that can be demodulated by the demodulation circuit 80 is changed in synchronization therewith. Turn off.

  The control circuit 90 can be configured by firmware having a memory, such as a digital signal processor (DSP) or a field-programmable gate array (FPGA). In the memory portion of these firmwares, the correspondence between the switching elements Z1 to Z4 and T1 to T4 in the zone selection unit 51 and the tuning selection unit 52 and the switching data b0 to b7 output from the serial parallel converter 70, That is, the switching table 91 in which the combination pattern of a plurality of reactances (in this example, capacitances of any of the inductors L1 to L5 and the capacitors C0 to C4) is recorded is stored. The control circuit 90 analyzes the broadcast frequency represented by the channel selection information, and uses the switching table 91 to generate switching data which is a control signal.

  An example of the contents of the switching table 91 is shown in FIG. Referring to FIG. 8, for example, when a narrow band antenna receives a 76 MHz signal, switching elements Z1 to Z3 are off (0), switching element Z4 is on (1), and switching elements T1 to T4 are all on (1). The switching data b0 to b7 are output so that Similarly, when receiving a 79.5 MHz signal, switching elements Z1 to Z3 are off (0), switching element Z4 is on (1), switching elements T1 to T2 are on (1) switching elements T3 and T4 are off The switching data b0 to b7 are output so as to be (0). The same is true for the other frequencies.

When the control circuit 90 receives tuning information from the vehicle receiver, the control circuit 90 serially outputs the clock CLK, data DATA, and strobe STB to the serial / parallel converter 60. Data DATA is data representing on (1) or off (0) described above, and is sequentially output to the switching circuit 50 at the timing when the strobe STB falls from logic high to logic low. The serial / parallel converter 60 converts the data DATA into parallel data (switching data b0 to b7) and outputs the parallel data to the switching circuit 50 in parallel to turn on or off the corresponding switching elements Z1 to Z4 and T1 to T4 simultaneously. Do. FIG. 9 is a diagram showing the output timing of data DATA. Here, an example in the case of receiving a broadcast frequency of 79.5 MHz is shown. That is, an example is shown in which the control circuit 90 controls the center frequency of the broadcast frequency to be demodulated by the demodulation circuit 80 to 79.5 MHz.
When the tuning information is the broadcast frequency in the AM wave band, all the data DATA is 0.

  In the antenna apparatus 1 configured as described above, for example, when receiving a broadcast frequency in the FM wave band, the narrow band antenna resonates only in a narrow band of 0.5 MHz. Therefore, there is no need to enable reception in the entire FM wave band, a design specialized for the required gain is possible, and there is a great advantage that microminiaturization becomes possible. In the case of changing the broadcast frequency to be received in the FM wave band, the load circuit may switch the reactance to be loaded. The demodulation circuit 80 also needs to demodulate only the frequency width at which the narrow band antenna resonates, so the configuration is simplified.

FIG. 10 is a characteristic diagram showing the relationship between the frequency of the FM waveband and the average gain. The broken line indicates the average gain G _w of the broadband antenna in which the coil element is connected to the planar element whose height from the surface of the ground potential is the same as that of the first embodiment. The solid line indicates the average gain by the antenna device 1 in the first embodiment. It is G _N. As apparent from FIG. 10, the fluctuation tendency of the average gain which fluctuates with the change of the frequency becomes the same as the wide band antenna, but in each broadcast frequency band, the average gain of the antenna device 1 according to the first embodiment is much higher Becomes higher.

FIG. 11 is a characteristic diagram showing the relationship between the frequency of the AM waveband and the output voltage level. The broken line indicates the output voltage level V _W of the wide band antenna, and the solid line indicates the output voltage level V _N of the antenna device 1 in the first embodiment. As apparent from FIG. 11, even if the antenna device 1 of the first embodiment is used instead of the wide band antenna, the output voltage level becomes equal or higher.

As described above, in the antenna device 1 according to the first embodiment, the narrow band antenna is configured by the metal element 40 and the inductors L1 to L4 separated by the respective taps from the coil element L, and reactance is adjusted according to the input channel selection information. Since the size is changed, it is possible to efficiently receive the signal, for example, over the entire frequency band of the FM wave band while being compact. In addition, the size reduction of at least the metal element 40 can be made more thoroughly, which can contribute to the further size reduction of the antenna device 1.
The reactance loaded on the metal element 40 is not limited to the inductance, and may be a capacitive reactance element that outputs capacitances of a plurality of sizes.

  In the first embodiment, since the metal element 40 has the surface portion facing the surface of the ground potential and the side portions 40a and 40b parallel to the surface of the ground potential, the radiation resistance is also obtained in the limited storage space. And gain can be increased. In addition, when producing the metal element 40 simply, it is not necessary to provide the both sides 40a and 40b.

  Further, in the first embodiment, the received AM waveband signal and the FM waveband signal are independently led to the post-stage circuit without being separated respectively, so that the branching loss and coupling are achieved. Not only the generation of loss can be suppressed, but also the device configuration can be simplified, which also contributes to the miniaturization.

  In the first embodiment, the control circuit 90 also determines the combination of the coarse adjustment reactance and the fine adjustment reactance so that the narrow band antenna resonates at the broadcast frequency in the FM wave band represented by the channel selection information, Since the zone selection unit 51 and the tuning selection unit 52 are controlled so that the reactance of the determined combination is loaded on the metal element 40, the resonance frequency in the narrow band antenna can be easily changed.

  In the first embodiment, the reactance loading means is configured by including the coil element L provided with a plurality of taps for taking out the inductance for each predetermined number of turns. Also, the zone selection unit 51 enables output of any one of the inductances L1 to ((L1 to L4), and the tuning selection unit 52 is a parallel circuit connected in series with the zone selection unit 51, And a plurality of lines in which the switching elements T1 to T4 are respectively inserted in the capacitors are connected in parallel. Therefore, the magnitude of the reactance loaded on the metal element 40 can be changed more easily.

  In the first embodiment, the control circuit 90 also holds the switching table 91 in which the combination pattern of reactance (for example, inductance or capacitance) in the zone selection unit 51 and the tuning selection unit 52 is recorded for each broadcast frequency. Identifying from the switching table a combination pattern of reactances that enables reception of the broadcast frequency represented by the channel selection information in response to the input of information, and controlling the zone selection unit 51 and the tuning selection unit 52 based on the identified combination pattern As a result, it is not necessary to calculate the magnitude of reactance each time channel selection information is input, and the processing load for control is reduced.

  The first embodiment also includes a serial / parallel converter 60 that generates a serial control signal based on the combination pattern identified by referring to the switching table 91 and converts the control signal into parallel data. Since the control means is configured to simultaneously control the zone selection unit 51 and the tuning selection unit 52 by parallel data, it is possible to suppress the occurrence of reception loss at the time of switching (loss of reception opportunity due to non-resonance).

  In the first embodiment, when the channel selection information indicates the broadcast frequency in the AM wave band, the coarse adjustment reactance in the zone selection unit 51 is opened to allow the latter stage circuit of the signal in the FM wave band broadcast frequency. Since the output to the output is blocked, it is possible to suppress the frequency interference in the subsequent circuit (for example, the AM signal amplifier circuit 71).

  In the first embodiment, the demodulation circuit 80 is configured to demodulate only the signal of the frequency band received by the narrow band antenna. The control circuit 90 controls which frequency band the signal to be demodulated belongs to. By configuring in this way, it is not necessary to demodulate other than the frequency band that is not received, and efficient reception becomes possible.

  In the first embodiment, the unit case 30 (30 ') detachably fixed to the antenna base 20 is also provided, and the unit case 30 (30') includes the switching circuit 50 as an example of a circuit unit. Since the serial parallel converter 60, the booster amplifier 70, the demodulation circuit 80 and the control circuit 90 are accommodated, the mounting work of the circuit unit on the antenna base 20 is simplified. It is not necessary to accommodate all the circuit units in the unit housing 30 (30 '), and the switching circuit 50 or the switching circuit 50 and the serial / parallel converter 60 are different from the unit housing 30 (30'). You may attach separately. The same applies to the booster amplifier 70 and the demodulation circuit 80.

Second Embodiment
Next, a second embodiment of the present invention will be described. The antenna device of the second embodiment differs from the antenna device 1 of the first embodiment in the mounting aspect of the circuit unit. About the same component as the antenna device 1 of 1st Embodiment, the same code | symbol is attached | subjected and duplication description is abbreviate | omitted.

  Fig.12 (a) is a side view which shows the example of mounting | wearing of the antenna component of the state which removed the antenna case 10 in the antenna apparatus 2 of 2nd Embodiment, FIG.12 (b) is a front view. An insulating antenna substrate 320 is vertically provided on the antenna base 20. The antenna substrate 320 is rectangular. In addition, the antenna substrate 320 is formed in a shape adapted to the storage space formed inside the antenna case 10, and the above-described metal element 40 is fixed to the upper end thereof. A central portion in the longitudinal direction of the metal element 40 is disposed on the same plane as the antenna substrate 320 and fixed to a portion higher than the upper edge of the antenna substrate 320. The switching circuit 50, the serial parallel converter 60, the booster amplifier 70, the demodulation circuit 80, and the control circuit 90 described in the first embodiment are directly mounted on the surface (for example, the left surface) of the antenna substrate 320. It is wired on the back surface (for example, the surface in the right direction) of 320.

  According to the antenna device 2 of the second embodiment, since the antenna substrate 320 is erected on the antenna base 20, the switching circuit 50, the serial / parallel converter 60, the booster amplifier 70, the demodulation circuit 80, and the control circuit 90 are provided. Even when housed in a housing space formed between the antenna case 10 and the antenna base 20, the length in the width direction (left and right direction) of the antenna case 10 (the length in the direction orthogonal to the long direction) Can be shortened.

In the first and second embodiments, although the embodiment in the case of being applied to a vehicle-mounted antenna device has been described, the antenna device of the present invention can be made thinner, so it is not limited to a vehicle-mounted antenna device. It is possible to implement as a type of antenna arrangement.
In the first and second embodiments, the embodiments in the case of receiving an AM waveband signal and an FM waveband signal have been described. However, digital television broadcast signals and other signals in the broadcast frequency band are described. It is also applicable to reception.

Claims (12)

A rod-like or band-like metal element capable of receiving a signal of a frequency width obtained by dividing a predetermined frequency band by loading a reactance;
Reactance loading means for loading the reactance on the metal element;
An antenna characterized by comprising: control means for receiving input of tuning information representing a selected frequency and changing a magnitude of the reactance loaded by the reactance loading means according to the selected tuning information. apparatus. A narrow band antenna resonating at the subdivided frequency width is configured by the metal element and a reactance element having the reactance,
The antenna device according to claim 1. The narrow band antenna is an antenna capable of receiving a signal of at least a first frequency band and a signal of a second frequency band,
The received signal of the first frequency band and the signal of the second frequency band are independently led to the subsequent stage circuit without being split.
The antenna device according to claim 2. The reactance loading means outputs a first reactance unit capable of outputting a coarse adjustment reactance for receiving a signal in the second frequency band, and a fine adjustment reactance for receiving a signal in the second frequency band. And a possible second reactance portion,
The control means determines and determines a combination of the coarse adjustment reactance and the fine adjustment reactance such that the narrow band antenna resonates when the tuning information indicates the frequency of the second frequency band. Controlling the first reactance unit and the second reactance unit such that reactances of different combinations are loaded to the metal element,
The antenna device according to claim 3. The reactance loading means includes a coil element provided with a plurality of taps for taking out an inductance for each predetermined number of turns,
The first reactance unit is configured to be able to output any one of the inductances extracted from the respective taps,
The second reactance unit is a parallel circuit connected in series to the first reactance unit, and a line of only a capacitor and a plurality of lines of which switching elements are inserted in the capacitors are connected in parallel. Characterized by being constituted by a circuit,
The antenna device according to claim 4. The control means holds a switching table in which a combination pattern of reactances in the first reactance unit and the second reactance unit is recorded for each frequency.
The combination pattern of reactances resonating at the frequency represented by the channel selection information is specified from the switching table in response to the input of the channel selection information, and the first reactance unit and the second reactance unit are determined based on the specified combination pattern. Characterized by controlling,
The antenna device according to claim 4 or 5. The control means includes a serial-to-parallel converter which generates a serial control signal based on the specified combination pattern and converts the control signal into parallel data.
Simultaneously controlling the first reactance unit and the second reactance unit according to the parallel data;
The antenna device according to claim 6. When the channel selection information indicates the frequency of the first frequency band, the control means causes the coarse adjustment reactance in the first reactance unit to be in an open state, thereby providing a circuit subsequent to the signal of the second frequency band. To block the output of
The antenna device according to any one of claims 4 to 7. The signal processing apparatus further comprises demodulation means for demodulating a signal of a frequency band received by the narrow band antenna,
The control means controls the demodulation means to demodulate a signal of a frequency represented by the tuning information.
The antenna device according to any one of claims 4 to 8. The demodulation means includes at least a first tuner that enables demodulation of a signal in the first frequency band, and a second tuner that enables demodulation of a signal in the second frequency band,
The control means switches the other operation off when operating either one of the first tuner and the second tuner.
The antenna device according to claim 9. Antenna case,
An antenna base in which a storage space is formed between the antenna case and the antenna case when the antenna case is fitted;
And a unit casing detachably fixed to the antenna base,
The metal element and the reactance loading means are housed in the housing space,
A circuit unit constituting at least one of the control means and the demodulation means is accommodated in the unit case.
The antenna device according to claim 9 or 10. When the antenna base is attached to the outside of a vehicle, the unit housing is fixed to the antenna base from the inside of the vehicle.
The antenna device according to claim 11.

Images