JP4109553B2 - Antenna module - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to antenna technology for a relay device provided as a dead zone countermeasure for mobile communication, for example. More specifically, the present invention relates to a mobile terminal such as a mobile phone radio (hereinafter referred to as “portable terminal”) and a relay device. The present invention relates to an antenna module that enables wireless communication without any obstacles.
[0002]
[Prior art]
In recent years, portable terminals that perform a call or data communication from an arbitrary place are rapidly spreading. A communication system enabling communication by a mobile terminal includes an exchange station connected to a public communication network and a radio base station connected to the exchange station. A plurality of radio base stations are provided for each service area. However, since the frequency band used is a high frequency band, when the mobile terminal is in a tunnel, underground mall, or building, for example, the radio wave does not reach or arrive at all. It has become difficult. Therefore, a relay device is generally provided in such an area, and radio waves from the radio base station are generally amplified by the relay device and redistributed. Such a relay apparatus is connected to the radio base station through, for example, an optical cable or radio communication means.
[0003]
FIG. 14 is a diagram illustrating a general configuration example of a radio base station and a relay device. In FIG. 14, the high frequency signal of the downlink (communication line from the radio base station to the portable terminal, the same applies hereinafter) transmitted from the radio base station 26 is converted into a light intensity modulation signal and transmitted through the downlink optical fiber 24. Then, it is guided to the base unit 211 of the relay device 21 through the input terminal 22. In the parent device 211, the light intensity modulation signal is reconverted into a high-frequency signal, then amplified, and guided to the child device group 212 via a coaxial cable connected to the pair of terminals 213 and 214.
On the other hand, the high frequency signal of the uplink (communication line from the portable terminal to the radio base station, the same applies hereinafter) sent from the slave unit group 212 is transmitted in the opposite direction to the downlink via the coaxial cable. 211, amplified here, converted into a light intensity modulation signal, transmitted through the output optical fiber 25 through the output terminal 23, and guided to the radio base station 26.
The above is the signal transmission path between the radio base station 26 and the relay device 21 and the function of each unit.
[0004]
A specific configuration example of the slave unit group 212 in the relay device 21 is shown in FIG.
In the slave unit group 212, a plurality of slave units each having an antenna module are connected in cascade through a coaxial cable and a high-frequency coupler. Reference numerals C-1, C-2,..., Cn indicate high-frequency couplers having a predetermined degree of coupling, reference signs D-0, D-1, ..., D- (n-1). The coaxial cable is indicated by (). Symbols A-1, A-2,..., An denote antenna modules, and symbols B-1, B-2,. Since all the slave units have the same configuration, hereinafter, in the case of explaining the component parts common to other slave units, the suffixes of the reference numerals for the component parts are omitted.
[0005]
Various antenna modules A are used depending on the service content (frequency band, slave unit installation location, etc.) of the relay device 21. Here, a ceiling-mounted monopole antenna as shown in FIG. 11 will be described.
This monomole pole antenna has a structure in which a coaxial connector 46 is disposed on the back side of the center of the antenna ground plane 42, and the central conductor of the coaxial connector 46 and the metal pole 43 protruding from the antenna radiation surface are electrically connected. ing. The protruding amount (height) of the metal pole 43 is about λ / 4 (λ is a free space wavelength). The directivity characteristic of the monopole antenna having such a structure has a predetermined directivity in the vertical plane as shown in FIG. 13A, and is almost omnidirectional in the horizontal plane as shown in FIG. 13B. .
[0006]
That is, the monopole antenna having the structure shown in FIG. 11 exhibits characteristics substantially equivalent to the radiation pattern of the dipole antenna, and the circumferential direction of the metal pole 43 is non-directional. When the diameter of the antenna ground plane 42 is infinite, the pattern characteristics parallel to the electric field component generated between the metal pole 43 and the ground plane (generally, directivity in the vertical plane) has the maximum directivity in the plane direction of the antenna ground plane 42. The axial component of the metal pole 43 is eliminated. As the diameter of the antenna ground plane 42 decreases, the component in the direction close to the axial direction of the metal pole 43 increases. Since this monopole antenna is intended to be attached to the ceiling or the like, it is set to about 1.7λ so that the radio wave can reach even immediately below. The structure and directivity of the monopole antenna having the structure shown in FIG. 11 are described in detail in pages 304 to 305 of the antenna handbook of CQ publisher.
[0007]
When a handset equipped with a monopole antenna having such a structure is installed on the ceiling of a room in a building where radio waves do not reach from the radio base station, the radio wave radiation state 20 radiated from the monopole antenna is shown in FIG. As shown in FIG. 4, the service can be received when there is no obstacle in the room or when a transmission / reception radio wave having a sufficient level in the system reaches the portable terminal. In FIG. 12, symbol A is the antenna module (monopole antenna) A described above.
[0008]
[Problems to be solved by the invention]
The antenna module A for a conventional relay device such as a monopole antenna has the following problems.
The first problem is that there is no degree of freedom in the installation location of the handset that is distributed.
In the conventional antenna module A, a sufficient margin for installation may not be obtained, or the antenna module A may not be installed on the ceiling due to building circumstances.
The second problem is that if each transmission wave of the slave unit and the portable terminal leaks to another slave unit or the portable terminal, it becomes noise in the other slave unit and causes deterioration in communication quality. For this reason, conventionally, in order to prevent extraneous radio waves from leaking outside the service area, the transmission power level is controlled as low as possible within the communicable limit, which leads to deterioration in reception sensitivity.
A third problem is that when a high frequency circuit is incorporated directly under the antenna of the slave unit in order to improve the reception sensitivity of the uplink from the portable terminal, the size of the slave unit is increased due to the addition of the high frequency circuit. Moreover, since it is necessary to prepare a power supply for a high frequency circuit for each slave unit, it is difficult to add a slave unit.
[0009]
The main object of the present invention is to provide a small antenna module that has a high degree of freedom in selecting an installation site and has excellent high-frequency characteristics.
[0010]
[Means for Solving the Problems]
An antenna module of the present invention that solves the above problems includes a module housing in which a connection interface for connecting via a coaxial cable to a transmission / reception end of a communication device such as a parent device of a relay device is formed, and an antenna A unit, and a high-frequency unit interposed in a signal transmission path between the antenna unit and the connection interface.
The antenna unit and the high frequency unit are accommodated in the module housing. The signal transmission path includes a downlink system that transmits a high-frequency signal for transmission from the communication device toward the antenna unit, and an uplink system that transmits a high-frequency signal received by the antenna unit toward the communication device. The high frequency unit includes a high frequency amplifier for enhancing the high frequency characteristics of the uplink system.
The power source that enables the high-frequency amplifier to operate is DC power supplied from the communication device through the connection interface and the coaxial cable.
[0011]
In such an antenna module, DC power is transmitted from a communication device via a coaxial cable, so that the high frequency unit can be operated without a power source on the antenna module side. Therefore, it becomes very easy to add an antenna module, and the installation site can be arbitrarily selected according to installation conditions (building structure, floor plan, tunnel height, radio wave coverage, etc.). Moreover, since the high frequency characteristics of the downlink system are enhanced by the high frequency unit, stable communication is possible. The “high frequency characteristics” referred to here include a noise figure of a high frequency signal, reception sensitivity at the time of signal reception, a received signal waveform, and the like.
[0012]
The module casing is a box-shaped casing, the box-shaped casing includes a plate-shaped antenna unit including a microstrip antenna, and a metal antenna case disposed on the back side of the microstrip antenna, A plate-like high-frequency unit disposed on the back side of the antenna case; and a bias substrate that is disposed on the back side of the high-frequency unit and supplies a bias for enabling the high-frequency amplifier included in the high-frequency unit; Is housed in the box-shaped housing, and the antenna unit, the high-frequency unit, and the ground line of the bias substrate are configured to be electrically connected to the antenna case, thereby realizing a thin box-shaped antenna module. .
[0013]
It is well known that a microstrip antenna is an antenna configured on a dielectric substrate and is thin and light in structure, easy to manufacture, and easy to integrate with a semiconductor circuit or the like. In the present invention, since the antenna module is configured using such a microstrip antenna, the overall size becomes extremely small, and the degree of freedom of the installation site can be remarkably increased as compared with the conventional case. For example, the antenna module can be used as a wall-mounted antenna that can be installed at an arbitrary place.
[0014]
In the above-described thin box-shaped antenna module, the high-frequency unit further includes a microstrip filter that restricts a passing frequency band of the signal transmission path of each of the downlink and uplink systems, thereby causing leakage radio waves. Can be held at a low level.
[0015]
As for the antenna unit, the entire size can be further reduced by mounting a microstrip antenna for both transmission and reception. On the contrary, the first microstrip antenna for the transmission band and the second microstrip antenna for the reception band are formed on the same substrate, so that the transmission / reception microstrip antenna is mounted. However, although the size is slightly increased, there is no need to synthesize and separate the transmission / reception signals, so that loss is reduced and reception sensitivity can be increased. From the viewpoint of further improving the reception sensitivity, the second microstrip antenna may be arranged to branch and connect a plurality of antenna elements with a predetermined positional relationship so as to have a reception diversity function.
[0016]
The antenna module of the present invention can also be implemented as an improved version of a monopole antenna. In this case, the antenna unit is a monopole antenna in which a pole-shaped antenna member is protruded from a surface portion of a predetermined antenna ground plane that forms a part of the module housing. The high-frequency unit includes the high-frequency amplifier that amplifies the high-frequency signal received by the antenna member on the high-frequency circuit board mounted on the back surface of the antenna ground plane, and the DC power as the main power source. It is assumed that a bias circuit for supplying a bias for enabling the high-frequency amplifier to operate is mounted.
Even in such an antenna module, from the viewpoint of suppressing leakage radio waves, the high-frequency unit is configured to include a microstrip filter that limits the pass frequency band of the signal transmission path in each of the downlink and uplink systems. It is desirable to do.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
<First Embodiment>
First, an embodiment when the present invention is applied to a wall-mounted antenna will be described.
FIG. 1 is an exploded perspective view showing the structure of a wall-mounted antenna according to this embodiment. This wall-mounted antenna 1 has a thin box-shaped housing composed of a resin antenna cover 35 and a back case 36 that serves both as an electrical shield and waterproof. Inside the housing, an antenna element substrate 31 that is an example of an antenna unit, a metal antenna case 32 that acts as an antenna ground plane, a high-frequency circuit substrate 33 that is an example of a high-frequency unit, and a bias substrate 34 Are stacked and accommodated in this order on the back side of the antenna element substrate 31. These sizes are determined by the frequency band used. In this embodiment, since the use frequency band is assumed to be 800 [MHz] to 2.0 [GHz], the size can be reduced.
The ground lines of the antenna element substrate 31 and the high frequency circuit substrate 33 are all connected to the antenna case 32.
[0018]
Although not shown, a coaxial connector connection terminal (connection interface) is provided at a predetermined portion of the casing, and the first signal input / output of the high-frequency circuit board 33 for the high-frequency signal transmission line portion of the coaxial cable. The central conductor portion of the coaxial cable is wired so as to be electrically connected to the power input terminal of the bias substrate 34. In addition, wiring between the bias substrate 34 and the high-frequency circuit substrate 33 and between the high-frequency circuit substrate 33 and the antenna element substrate 31 are also made.
[0019]
The antenna element substrate 31 is equipped with a microstrip antenna for both transmission and reception. Regarding the structure and radiation characteristics of the microstrip antenna, reference can be made to the description of pages 91 to 111 of “Small and Planar Antenna” (Incorporated) by the Institute of Electronics, Information and Communication Engineers (hereinafter referred to as a reference). As is apparent from the description on page 102 of the reference, this microstrip antenna has substantially the same radiation characteristics in both a circular shape and a rectangular shape.
[0020]
Since the position of the antenna case 32 with respect to the antenna element substrate 31 contributes to the reflection characteristics of the entire antenna module, the positions of both may be determined according to the desired reflection characteristics. In addition, the lower the dielectric constant of the antenna element substrate 31 and the thicker the substrate thickness, the wider the band can be matched. Therefore, the dielectric constant and the substrate thickness are determined in accordance with the use frequency band. In this embodiment, a minimum gap (about 5 mm) is selected on the assumption that sufficient matching can be achieved in the band covering the transmission / reception band and that the whole is thin. The theoretical support for the above properties and sizes is described in detail on page 111 of the reference.
[0021]
The antenna element substrate 31 and the high-frequency circuit board 33, and the high-frequency circuit board 33 and the coaxial connector connection terminal on the casing are wired, so that each of the downlink system and the uplink system is provided on the high-frequency circuit board 33. Signal transmission paths are formed. Among these signal transmission paths, a microstrip type band pass filter (BPF) and a high frequency amplifier are inserted and connected in series in the downlink system, and the BPF is inserted and connected in the uplink system. In addition, power for distributing and integrating signal transmission paths is respectively provided to the first signal input / output terminal in the immediate vicinity of the coaxial connector connection terminal and the second signal input / output terminal in the immediate vicinity of the antenna element substrate 31. A distributor / synthesizer is provided.
[0022]
The bias substrate 34 generates a bias voltage having a value that enables operation of an active element mounted on the high-frequency circuit substrate 33, that is, a high-frequency amplifier to be described later, based on the DC power supplied from the power input terminal. And components for controlling ON / OFF of the high-frequency amplifier are mounted. More specifically, a passive element such as a capacitor and a resistor and an active element for performing the control are mounted.
[0023]
In the wall-mounted antenna 1 shown in FIG. 1, an equivalent circuit when the antenna element substrate 31, the antenna case 32, the high-frequency circuit substrate 33, and the bias substrate 34 are accommodated in the casing and becomes operable is shown in FIG. 2. Show.
The wall-mounted antenna 1 in an operable state includes an antenna element 2 that operates in both transmission and reception frequency bands, a power distributor / combiner 6, a BPF 3 inserted and connected to the uplink system, a high-frequency amplifier 4, and a downlink system. It has a BPF 5 to be inserted and connected, a power distributor / combiner 7, and a coaxial cable connection terminal 8.
[0024]
By providing the high-frequency amplifier 4 and the BPF 3, particularly the high-frequency amplifier 4, in the uplink system between the antenna element substrate 31 and the power distributor / combiner 7, the high-frequency characteristics in the antenna element substrate 31 provide the high-frequency amplifier 4. This is much higher than when there is no such thing. This will be described below by taking a noise figure as an example.
When the high frequency circuit board 33 is not provided, the noise figure viewed from the feeding point of the antenna element board 31 to the coaxial cable connection terminal 8 side is Fo, the noise figure of the high frequency amplifier 4 is Fa, the noise figure of the BPF 3 is Ff, and the high frequency amplifier 4 When the gain is G, the noise figure when the coaxial cable connection terminal 8 side is viewed from the feeding point of the antenna element board 31 when the high frequency circuit board 33 is provided, that is, the noise figure F of the uplink system is a value represented by the following equation: Is approximated by
F = Ff. (Fa + (2.Fo-1) / G)
In the above equation, the noise figure is expressed as a true number, but it can also be expressed as a logarithm.
[0025]
Normally, the noise figure Fo is about 30 dB (1000 in the true number). The power distributor / combiner 7 has a loss of 3 dB with respect to the uplink system, and the noise figure increases by 3 dB (2 in the true number). Therefore, the noise figure at the output terminal of the uplink high-frequency amplifier 4 is 33 dB (2000 in the true number) at 2 Fo. The noise figure 2Fo becomes Fa + (2 · Fo−1) / G at the input terminal of the high-frequency amplifier 4 by interposing the high-frequency amplifier 4 having the noise figure of Fa and the gain of G. This is well known and will not be described here. If Fa is 2 dB (1.58 in the true number) and G is 30 dB (1000 in the true number), then 10 log (Fa + (2 · Fo−1) / G) = 5.5 dB (3.59 in the true number). Become.
Therefore, the noise figure F becomes 6.5 dB (4.5 in the true number) when the loss Ff of the BPF 3 is 1 dB. Thus, the noise figure F is improved to 6.5 dB compared with the case where the high frequency circuit board 33 is not provided (30 dB). An improvement in the noise figure of the uplink system is equivalent to a reduction in the noise power density of the uplink system. Can be found by evaluating (bandwidth).
[0026]
Specifically, it is as follows.
The uplink noise power density Pf can be approximated to thermal noise per 1 Hz when the gain of the entire uplink system is Gs, and can be expressed as follows.
Pf = −174 + F + Gs (dBm / Hz)
In this embodiment, since the noise figure F is 6.5 dB, the noise power density Pf is as follows when the gain Gs is 30 dB.
Pf = −174 + 6.5 + 30 = −137.5 (dBm / Hz)
On the other hand, the noise power density by the conventional antenna module under the same conditions is as follows.
Pf = −174 + 30 + 30 = −114 (dBm / Hz)
[0027]
As described above, by inserting the high-frequency circuit board 33, particularly the high-frequency amplifier 4 in the uplink system as in this embodiment, the noise power density is 23.5 dB low, that is, the reception sensitivity is improved by 23.5 dB. I understand that. As a result, the signal-to-noise ratio (S / N ratio) of the uplink system is greatly improved, and communication failure due to sensitivity deterioration is avoided.
[0028]
A power source that enables the high-frequency amplifier 4 to operate is supplied to the bias substrate 34 via a coaxial cable that is superimposed on a high-frequency signal from the side of the communication device that uses the wall-mounted antenna 1, for example, the base unit 211 shown in FIG. DC power supplied to the bias substrate 34 after being adjusted to a predetermined value. Since the technique itself for superimposing the DC power on the high-frequency signal is a known technique (for example, a function of a known multiplexer), detailed description thereof is omitted here.
As described above, the wall-mounted antenna 1 itself does not need to be provided with a power source. Therefore, it is possible to reduce the size and weight from this point. In addition, when the antenna is used as a slave unit of a relay device, There is an advantage that expansion is easy.
[0029]
The directivity characteristics of the wall-mounted antenna 1 of this embodiment configured as shown in FIG. 1 are as shown in FIG. That is, the horizontal plane directivity is as shown in FIG. 8A, and the vertical plane directivity is as shown in FIG. 8B. The directivity is 90 °. This is clear from the description in FIG. 4.8 on page 100, FIG. 4.9 on page 101, FIG. 4.10 on page 102, and pages 94 to 102 in the above-mentioned reference.
[0030]
The wall-mounted antenna 1 according to the present embodiment is installed at a corner of a room or the like, so that the radiation direction is limited to that room as shown in the radio wave radiation state 10 in FIG. Greatly improved.
[0031]
Second Embodiment
In the wall-mounted antenna of the first embodiment, the antenna element substrate 31 is used for both transmission and reception. However, a wall-mounted antenna with improved reception sensitivity can be obtained by separating the transmission / reception antenna.
FIG. 3 is a plan view of the antenna element substrate 41 in the transmission / reception antenna separation system. On this antenna element substrate 41, a transmitting antenna element 411, a receiving antenna element 412, and feed points K41-1 and K41-2 are formed. When incorporating into the module housing, the antenna element substrate 31 of the first embodiment shown in FIG. 1 is replaced with the antenna element substrate 41 of FIG. 3, and the high-frequency circuit board 33 is adjusted to the feeding points of the antenna elements 411 and 412. The structure is the same as that of FIG. 1 except that the connection position with the antenna is changed.
[0032]
FIG. 4 is an equivalent circuit of the wall-mounted antenna having the antenna element substrate 41 of FIG. 3 and has a structure in which the transmitting antenna 2-1 and the receiving antenna 2-2 are separated. 2 is the same as the wall-mounted antenna of the first embodiment, except that the power distribution / combining device (power distribution / combining device 6 in FIG. 2) that separates the uplink system from the uplink system becomes unnecessary.
In this way, the transmission / reception antenna separation type wall-mounted antenna can reduce the number of power distribution / combining devices by one compared to the transmission / reception antenna, thereby reducing the noise figure and increasing the reception sensitivity accordingly. be able to.
[0033]
<Third Embodiment>
As an application of the transmission / reception antenna separation method as in the second embodiment, it is possible to provide a function of reception diversity.
FIG. 5 is a plan view of the antenna element substrate 51 when realizing a wall-mounted antenna having a reception diversity function.
The antenna element substrate 51 is formed with a transmitting antenna element 511, receiving antenna elements 512, 513, and respective feeding points K51-1, K51-2, K51-3. When incorporated in the module housing, the antenna element substrate 31 of the first embodiment shown in FIG. 1 is replaced with the antenna element substrate 51 of FIG. 5, and the antenna of the high-frequency circuit board 33 is matched to the position of the feeding point of each antenna element. The structure is the same as that of FIG. 1 except that the end position is changed.
FIG. 6 is an equivalent circuit of a wall-mounted antenna incorporating the antenna element substrate 51 of FIG. Except that the transmitting antenna 2-1 and the two receiving antennas 2-2 and 2-3 are arranged, the circuit is the same as the equivalent circuit of the second embodiment.
As described above, by providing the wall-mounted antenna with the reception diversity function, the position dependency of the mobile terminal is reduced, and the adverse effect of the obstacle in the radio wave path is also improved.
[0034]
<Fourth embodiment>
The present invention can also be implemented as a ceiling-mounted monopole antenna.
FIG. 9 is a perspective view showing a structure when the present invention is applied to a monopole antenna, and FIG. 10 is a sectional structural view thereof. Since this monopole antenna is used for both transmission and reception, an equivalent circuit as an antenna module is the same as that of FIG.
[0035]
This monopole antenna includes a high-frequency amplifier and a BPF mounted on the high-frequency circuit board 33 described in the first embodiment, as shown in an external perspective view (partially cutaway) in FIG. 9 and a side sectional view in FIG. The bias substrate 34 is mounted on a single circuit board 15 to constitute a high-frequency unit, and the circuit board 15 is disposed inside the back surface of the monopole antenna ground plane 12 (behind the antenna radiation surface). The metal pole 11 having a predetermined dimension is attached. The metal pole 11 is joined to the central conductor 14 of the coaxial cable. What is indicated by reference numeral 13 is a resin antenna cover.
The size and operation principle of the metal pole 11 and the like are the same as those of the conventional monopole antenna shown in FIG.
In the monopole antenna of this embodiment, the DC power transmitted from the communication device side is supplied to the bias circuit through the central conductor 14 of the coaxial cable, and the bias voltage adjusted by this bias circuit is supplied to the high-frequency amplifier. This high frequency amplifier is the same as the first embodiment in that the high frequency characteristic of the uplink system, for example, the noise figure is improved. Therefore, it is possible to remarkably increase the high frequency characteristics of the uplink system, particularly the noise figure, without increasing the overall size, thereby contributing to performance improvement.
[0036]
As described above, in each embodiment of the present invention, in addition to the conventional ceiling-mounted antenna, various types of wall-mounted antennas are added as one of the menus of the antenna module, thereby installing the slave unit. Various types of antennas can be selected in accordance with the place to perform.
For example, in the case of a room facing a building window, the transmission wave is more likely to be emitted outside the building, but a wall-mounted antenna should be used depending on the structure of the room in the service area and the condition of the obstacle. That's fine. The antenna directivity can be optimized and directed to the interior of the room.
[0037]
In each of the above embodiments, the antenna module used in the relay device between the mobile phone and the wireless base station has been described. However, the antenna module of the present invention is a wireless communication device for general communication devices. It can also be used as one of the communication means.
[0038]
【The invention's effect】
As is clear from the above description, according to the present invention, it is possible to provide an antenna module having a structure that can be arbitrarily adapted according to installation conditions. By selecting the optimum antenna directivity according to the arrangement conditions, it is possible to suppress the leaked radio wave that becomes an obstacle to other communication devices to a low level.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the structure of a wall-mounted antenna according to the present invention.
FIG. 2 is an equivalent circuit of a wall-mounted antenna according to the first embodiment and the fourth embodiment.
FIG. 3 is a plan view of an antenna element substrate according to a transmission / reception antenna separation system of a second embodiment.
FIG. 4 is an equivalent circuit of a wall-mounted antenna based on a transmission / reception antenna separation system according to a second embodiment.
FIG. 5 is a plan view of an antenna element substrate of a wall-mounted antenna having a reception diversity function according to a third embodiment.
FIG. 6 is an equivalent circuit of the wall-mounted antenna according to the third embodiment.
FIG. 7 is an explanatory diagram showing the installation location and radio wave radiation state of the wall-mounted antenna of the present invention.
FIGS. 8A and 8B are directivity characteristics diagrams of the wall-mounted antenna of the present invention.
FIG. 9 is an external perspective view (partially cut away) of a ceiling-mounted monopole antenna module according to a fourth embodiment.
FIG. 10 is a side sectional view of a ceiling-mounted monopole antenna module according to a fourth embodiment.
FIG. 11 is an external perspective view (partially cut away) showing the structure of a conventional ceiling-mounted monopole antenna.
FIG. 12 is an explanatory diagram showing the installation location and radio wave radiation state of a conventional ceiling-mounted monopole antenna.
13A and 13B are directional characteristics diagrams of a conventional ceiling-mounted monopole antenna.
FIG. 14 is a diagram showing a relationship between a conventional radio base station and a relay device.
FIG. 15 is a configuration diagram of a slave unit group of a conventional relay device.
[Explanation of symbols]
1 Wall-mounted antenna
2, 2-1, 2-2, 2-3 Antenna element
3, 5 BPF
4 High frequency amplifier
6, 7 Power distribution / synthesizer
8 Coaxial cable connection terminal
10,20 Radio wave emission state
11, 43 Metal pole
12, 42 Ground plate for antenna
13 Antenna cover
14 Center conductor
15 Circuit board (high frequency unit)
31, 41, 51 Antenna element substrate
32 Antenna case
33 High-frequency circuit board
34 Bias substrate
35 Antenna cover
36 Back Case
46 Coaxial connector
411, 412, 511, 512, 513 Antenna element
A Antenna module
B Antenna connection end
C high frequency coupler
D Coaxial cable

Claims (7)

This is an antenna module having a connection interface for connecting to a transmission / reception end of a communication device via a coaxial cable, and having a housing composed of an antenna cover and a rear case serving both as an electrical shield and waterproof. And
A plate-shaped antenna unit on which a microstrip antenna is formed , a metal antenna ground plane, a high-frequency circuit board on which a high- frequency circuit interposed in a signal transmission path between the antenna unit and the connection interface is mounted, and the high-frequency circuit A bias substrate for supplying a bias that enables the operation of the antenna cover and being stacked in this order from the back surface of the antenna cover toward the back case, and housed in the housing,
The antenna unit and the ground line of the high-frequency circuit board are electrically connected to the antenna case,
The signal transmission path is:
A downlink system that transmits a high-frequency signal for transmission from the communication device toward the antenna unit, and an uplink system that transmits a high-frequency signal received by the antenna unit toward the communication device. And
The high-frequency circuit board is
A filter and a high frequency amplifier are mounted as the uplink high frequency circuit, and a filter is mounted as the downlink high frequency circuit ,
The power supplied to the bias substrate is DC power supplied from the communication device through the connection interface and the coaxial cable.
Antenna module. The filter mounted on the high-frequency circuit board is a microstrip filter that limits a pass frequency band of the signal transmission path of each of a downlink system and an uplink system.
The antenna module according to claim 1 . The antenna unit is equipped with a microstrip antenna for transmission and reception.
The antenna module according to claim 2 . In the antenna unit, a first microstrip antenna for a transmission band and a second microstrip antenna for a reception band are formed on the same substrate.
The antenna module according to claim 2 . The second microstrip antenna is provided with a reception diversity function by arranging a plurality of antenna elements to be branched and connected in a predetermined positional relationship.
The antenna module according to claim 4 . Instead of the microstrip antenna, the antenna unit is configured by projecting one pole-shaped antenna member from the surface portion of the antenna ground plane,
The high frequency circuit board and the bias board are mounted on a single circuit board to constitute a high frequency unit,
This high frequency unit is mounted on the back surface of the antenna ground plane.
The antenna module according to claim 1. The high-frequency unit is configured to include a microstrip filter that limits a pass frequency band of the signal transmission path of each of a downlink system and an uplink system.
The antenna module according to claim 6 .

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