JPH09318689A - Shield box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shield box constructed at low costs with little influence between adjacent ground stations. SOLUTION: In a shield box 1, electromagnetic waves are shielded from the outside, a uni-directional corner reflector antenna 11 is prevented from receiving reflection waves produced in the surface of the shield box 1 to which no electromagnetic wave absorbers 1c-1 or 1c-2 are stuck and, in this condition, measuring is performed only by transferring direct waves with the antenna 2a of a portable telephone set 2. The uni-directional corner reflector antenna 11 is constructed by attaching a corner reflector 11b to a dipole antenna 11a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield box suitable for use in a transmission / reception test of a wireless terminal or the like.

[0002]

2. Description of the Related Art In recent years, mobile phones such as mobile phones, wireless data terminals, etc. (hereinafter referred to as mobile wireless terminals or mobile wireless terminals) have been remarkably developed and spread, and demand for them is further increasing. Is also expected. As a result, the development cycle of these mobile wireless terminals has become shorter, and the number of repairs and the like has increased significantly.

[0003] When a mobile radio terminal is developed, shipped, or repaired, a performance test (performance test) of the device is indispensable. As one of the performance inspections, there is an inspection of the quality of transmission radio waves (transmission power, occupied frequency bandwidth, frequency deviation, etc.) and reception sensitivity (hereinafter, referred to as transmission / reception inspection).

Conventionally, a mobile radio terminal has a detachable high-frequency terminal (connector), and a transmitting / receiving antenna is attached to this high-frequency terminal. Also, even if the transmitting and receiving antenna is directly attached to the main body of the mobile wireless terminal,
A high-frequency terminal was separately provided. Therefore, a tester having a wattmeter, a spectrum analyzer, a standard signal generator, or the like is connected to a high-frequency terminal by a high-frequency cable to perform a transmission / reception test.

However, with the spread of mobile radio terminals in recent years, mobile radio terminals have been required to be smaller and lighter and have lower prices. For this reason, models without a high-frequency terminal and having a transmitting / receiving antenna directly attached to the main body have been developed.

Therefore, in such a mobile radio terminal not equipped with a high frequency terminal, there is no choice but to use a measuring method generally called air coupling. The air coupling is to install a measurement antenna at a predetermined distance from a transmission / reception antenna attached to a mobile wireless terminal, and to transmit / receive a test radio wave using the measurement antenna.

However, according to the air coupling, radio waves are transmitted from the transmitting / receiving antenna and the measurement antenna of the mobile radio terminal, which affects nearby base stations. These antennas also receive radio waves from nearby base stations and unnecessary radio waves such as noise. Further, the reflected waves generated when the radio waves transmitted from these antennas hit a nearby metal object or the like cannot be ignored.

Therefore, such transmission / reception inspection by air coupling is ideally performed in an anechoic chamber in which the electromagnetic field is mutually cut off from the outside world and there is no internal reflection, but the anechoic chamber is extremely expensive. Not so easily adopted. Therefore, inexpensive and easy shield boxes have been developed and used in place of such expensive anechoic chambers.

FIG. 5 is an example of a conventional shield box and is a perspective view showing the overall structure. The seed box 101 includes a housing 101a and a lid 101b, both of which are formed of a metal having a shielding effect against a high-frequency electromagnetic field.

An opening surface is provided on one surface (upper surface in FIG. 5) of the housing 101a, and the mobile phone 102 is opened from this opening surface.
(Mobile wireless terminal) can be taken in and out. The lid 101b has a shape that covers the opening surface and shields the mobile phone 102 stored inside the shield box 101.

Inside the casing 101a, there is a table (not shown) on which the mobile phone 102 is placed, and a dipole antenna (not shown) below the table.
This table is made of a material that transmits electromagnetic waves without any problem, and enables air coupling between the antenna 102a attached to the mobile phone 102 and the dipole antenna.

Another surface of the casing 101a (side surface in FIG. 5)
Has a high-frequency terminal 103a and a control terminal 103b. This high-frequency terminal 103a is connected to the above-mentioned dipole antenna (not shown). Also, the control terminal 103
“b” connects to the voice terminal of the mobile phone 102 or the data terminal when measuring a wireless data terminal.

[0013]

Of the above-mentioned lid 101b.
Electromagnetic wave absorber 101c on the inner surface_-1Is affixed to the housing
The electromagnetic wave absorber 101c is provided on the inner surface of the bottom of the 101a._-2Affixed
Have been. Furthermore, the inner surface of the front side of the housing 101a and the rear side
Each of the inner surfaces has a radio wave absorber 101c._-3Or 101c
_-Four, The electromagnetic wave absorber 101 on the inner surface on the left side and the inner surface on the right side.
c _-FiveOr 101c_-6Is attached (hereinafter, this
Radio wave absorber 101c_-1, 101c_-2... 101
c_-Five, 101c_-6The radio wave absorber 10 if necessary.
1c). This electromagnetic wave absorber 101c has various
Has been developed but is well known, so here is the details
A detailed description will be omitted.

The radio wave absorber 101c absorbs an incident electromagnetic wave and does not generate a reflected wave. Shield box 101
Since the inside is shielded from the outside, only direct waves are transmitted and received between the antenna 102a of the mobile phone 102 and a measurement dipole antenna (not shown). Therefore, they do not affect each other with external devices or noise sources.

By the way, as described above, the electromagnetic wave absorber 10
There are many kinds of 1c, and the one that has the frequency and the degree of attenuation of the electromagnetic wave to be absorbed according to the purpose is selected. However, as shown in this example, the radio wave absorber is often extremely expensive in applications where the inner volume is relatively small and high attenuation performance is required.

Therefore, there is a problem that the shield box 101 itself becomes expensive. The present invention has been made under such a background, and an object thereof is to provide a shield box which can be constructed at a low cost without mutual influence with neighboring base stations and the like.

[0017]

In order to solve the above-mentioned problems, in the invention described in claim 1, the two facing
Conductive storage means for storing a wireless terminal having a transmitting and receiving antenna formed of a flat surface and another surface, a radio wave absorbing means affixed to an inner surface of the flat surface portion of the storage means, and inside the storage means. A mounting means for mounting the wireless terminal, a measuring antenna having a single directivity and having a directivity axis intersecting the transmitting / receiving antenna and the two planes, and one end surface of the storing means. It has a high frequency terminal attached and connected to the measuring antenna.

Further, in the invention described in claim 2,
The shield box according to claim 1, wherein the measuring antenna includes a dipole antenna parallel to the transmitting / receiving antenna, and a corner reflector formed of two plane plates parallel to the dipole antenna and intersecting each other. Is characterized by.

According to the present invention, electromagnetic waves are shielded from the outside by the inside of the shield box, and the unidirectional measuring antenna reflects off the surface of the shield box to which the electromagnetic wave absorbing means is not attached. Without receiving the waves, only the waves are directly transmitted / received to / from the transmission / reception antenna of the wireless terminal for measurement. A unidirectional measuring antenna is constructed by attaching a corner reflector to a dipole antenna.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below.
FIG. 1 is a side sectional view showing a configuration of a shield box 1 according to one embodiment of the present invention. In the present embodiment, an example in which the mobile phone 2 is applied as a mobile wireless terminal will be described.

In FIG. 1, reference numeral 1a denotes a housing, which has an U-shaped cross section as an example of the shape as shown in FIG. In FIG. 1, the upper surface of the housing 1a is an opening surface.

Reference numeral 1b denotes a lid, which has a shape covering the opening surface of the housing 1a. When the opening surface of the housing 1a is closed by the lid 1b, the shield box 1 of the present embodiment has a cubic external shape. Becomes

Both the housing 1a and the lid 1b are made of a metal (for example, aluminum or the like) that has a shielding effect on a high frequency electromagnetic field. Therefore, the electromagnetic wave is shielded from the outside in the shield box 1.

Reference numeral 1c _-1 is a radio wave absorber attached to the inner surface of the lid 1b in order to prevent reflection of electromagnetic waves. Reference _numeral 1c- ₂ is a radio wave absorber attached to the inner surface of the bottom of the housing 1a for the same purpose.

A table 10 for mounting the mobile phone 2 is provided inside the housing 1a. The table 10 is made of a material such as acrylic resin that allows electromagnetic waves to pass therethrough without any problem, and the upper surface of the upper base 10a of the table 10 is provided with a mat made of silicone resin or the like and is placed thereon. Mobile phone 2
Has a structure that does not slide easily.

The mobile phone 2 shown in this embodiment has an antenna 2a. On the other hand, a corner reflector antenna 11 is attached to a position facing the antenna 2a with the upper base 10a sandwiched in the housing 1a,
It is connected to a high frequency terminal 3 provided on one side surface of the housing 1a.

FIG. 2 is a perspective view showing a detailed structure of the corner reflector antenna 11. As shown in FIG. 2, the corner reflector antenna 11 is the dipole antenna 1
1a and a corner reflector 11b.

The corner reflector 11b is composed of two reflectors 11b- ₁ and 11b- ₂ forming a predetermined included angle. These reflectors 11b- ₁ and 11b- ₂ are generally conductor plane plates and are attached parallel to the dipole antenna 11a. Due to this corner reflector 11b, the corner reflector antenna 11 exhibits a remarkable directional characteristic in the Z-axis direction shown in FIG.

FIG. 3 is a diagram showing the directional characteristics of the corner reflector antenna 11 shown in FIG. 2, and FIG. 3 (a) shows the directional characteristics of the magnetic field surface (YZ plane: for example, this is the vertical surface). 3B shows the directional characteristics of the electric field surface (XZ plane: for example, this is a horizontal plane). In addition,
The corner reflector antenna 11 in FIG. 3 is assumed to have an included angle of about 90 ° between the reflector 11b _-1 and the reflector 11b _-2 .

Normally, the directional characteristic of the dipole antenna 11a exhibits non-directionality (circular characteristic) on the magnetic field surface and bidirectionality (8-shaped characteristic) on the electric field surface. However, the corner reflector antenna 11 has a unidirectional directivity in the opening direction of the corner reflector 11b, and the directivity is relatively strong especially in the magnetic field plane, and its half-value angle (the gain from the azimuth with the highest sensitivity is 2
The angle width which becomes 1 / () is equal to the reflection plate 11b _-1 and the reflection plate 11b.
_-Depends on the included angle with _-2 .

In this embodiment, first, the lid 1b of the shield box 1 is opened, and the mobile phone 2 is placed on the table 10 in the housing 1a. At this time, the mobile phone 2 is placed at a predetermined position, and the antenna 2a of the mobile phone 2 and the measuring corner reflector antenna 11 are opposed to each other in a predetermined positional relationship.

As described above, the upper table 10a of the table 10
The upper surface of the is provided with a mat of silicon resin or the like.
Since the surface of the silicone resin mat has an extremely large coefficient of friction, the position of the mounted mobile phone 2 is fixed.

Next, by closing the lid 1b of the shield box 1, the mobile phone 2 is shielded from the outside world by electromagnetic waves. In the shield box 1 of the present embodiment, the electromagnetic wave absorber is not attached to any of the inner side surfaces of the housing 1a. Moreover, since the housing 1a is formed of a metal or the like having a shielding effect, surface reflection is generally generated.

FIG. 4 is a side perspective view showing how electromagnetic waves propagate inside the shield box 1. The figure shows a case where the corner reflector antenna 11 receives an electromagnetic wave transmitted from the antenna 2 a of the mobile phone 2.

Generally, the antenna 2a included in the mobile phone 2
Is designed to emit electromagnetic waves in all directions because of its weak directivity. Therefore, electromagnetic waves are emitted in any of the X-axis, Y-axis, and Z-axis directions shown in FIGS.

Of these, the electromagnetic wave radiated in the -Z direction is directly incident on the corner reflector antenna 11.
That is, this electromagnetic wave is converted into a direct wave by the corner reflector 11
Will be received at.

The electromagnetic wave radiated in the Z direction is covered by the lid 1b.
Wave absorber 1c attached to the inner surface of the _-1Incident on. this
Therefore, this electromagnetic wave is generated by the electromagnetic wave absorber 1c._-1Absorbed by and measured
There is no reflected wave that affects the.

On the other hand, the electromagnetic waves radiated in the ± X and ± Y directions are incident on the inner surface of the side portion of the casing 1a. Case 1a
Is formed of a metal or the like having a shielding effect as described above, and in many cases, its surface reflects electromagnetic waves.

That is, when the electromagnetic wave indicated by the solid line in FIGS. 4A and 4B is incident on the inner surface of the side portion of the casing 1a, a reflected wave indicated by the broken line is generated, and the reflected wave is generated along with the above-mentioned direct wave at the corner. It is incident on the reflector antenna 11.

By the way, the corner reflector antenna 11
Has a directional characteristic as shown in FIG.
The gain in the X-axis or Y-axis direction shown in is extremely low. That is, it does not show effective sensitivity to electromagnetic waves incident from the X-axis or Y-axis direction.

Therefore, the reflected wave generated on the inner surface of the side portion of the casing 1a is not received by the corner reflector antenna 11. Therefore, it is possible to perform measurement without being influenced by a neighboring base station, a noise source, or the like, and without being influenced by reflection of electromagnetic waves in the shield box.

That is, according to the present embodiment, since the surface (area) to which the electromagnetic wave absorber has to be attached is small in the shield box, it is possible to suppress an increase in manufacturing cost due to the frequent use of expensive electromagnetic wave absorbers. .

Further, since it can be constructed by simply adding a corner reflector to a conventional shield box having a built-in dipole antenna, it is possible to keep the development cost low.

In the above-described embodiment, the mobile phone 2
The case where the corner reflector antenna 11 receives the electromagnetic wave transmitted from the antenna 2a included in the above has been described as an example. However, the antenna 2 that the mobile phone 2 has the electromagnetic waves transmitted from the corner reflector antenna 11
Since the same operation is brought about even when it is received by a, its explanation is omitted.

Further, although the corner reflector antenna is used as the measurement antenna in the same embodiment, an antenna having a relatively strong directivity in one direction, a small side lobe, and a small external shape (for example, a microstrip antenna, Any microstrip array antenna) can be applied to the present invention.

Further, the corner reflector can also be constituted by a net (lattice) having conductivity in addition to the conductor plane plate shown in this embodiment. In addition, the included angle between these two reflectors such as a conductor plane plate and a net depends on the directivity characteristics of the corner reflector antenna determined by the frequency of the electromagnetic wave to be measured, the length of the dipole antenna, and the external shape of the shield box. It is determined accordingly.

In the present embodiment, an example in which the mobile phone is stored in the shield box has been described, but the present invention can be applied to all mobile wireless terminals such as wireless data terminals other than the mobile phone.

Further, in the present embodiment, the configuration in which the mobile phone is fixed by the silicone resin mat placed on the upper surface of the upper base of the table has been described as an example, but in addition to this, a fixing band or the like is fixed on the upper base. It may be provided with a tool.

Further, although the shield box in the present embodiment has a cubic shape, it may have, for example, a cylindrical shape as long as it has two opposing (parallel) flat surfaces on which the radio wave absorber can be attached. Is applicable.

[0050]

As described above, according to the present invention, electromagnetic waves are mutually shielded from the outside in the shield box, and the unidirectional measuring antenna has the electromagnetic wave absorbing means attached inside the shield box. The measurement is performed by directly transmitting / receiving only the wave to / from the transmission / reception antenna of the wireless terminal, without receiving the reflected wave generated on the surface that is not reflected. Moreover, since the unidirectional measuring antenna is constructed by attaching a corner reflector to the dipole antenna, it is possible to realize a shield box that can be constructed at low cost without mutual influence with neighboring base stations and others. The effect that there is is obtained.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a configuration of a shield box 1 according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a detailed configuration of a corner reflector antenna 11 in the same embodiment.

3 is a diagram showing directional characteristics of a magnetic field surface and an electric field surface of the corner reflector antenna 11 shown in FIG.

FIG. 4 is a side perspective view showing how electromagnetic waves propagate inside a shield box 1 according to the same embodiment.

FIG. 5 is a perspective view showing an example of a conventional shield box, showing an overall configuration.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 shield box (storage means) 1a housing (storage means) 1b lid (storage means) 1c _-1 , 1c _-2 electromagnetic wave absorber (electromagnetic wave absorption means) 2 mobile phone (wireless terminal) 2a antenna (transmission / reception antenna) 3 High-frequency terminal 10 Table (mounting means) 10a Upper base (mounting means) 11 Corner reflector antenna (measurement antenna) 11a Dipole antenna 11b Corner reflectors 11b- ₁ and 11b- ₂ Reflector (planar plate)

Claims (2)

[Claims] 1. Formed from two opposing flat surfaces and another surface
Wireless terminal (2) having a transmitting / receiving antenna (2a)
A conductive storage means (1, 1a, 1b) for storing an electric wave and an electromagnetic wave affixed to the inner surface of the two flat surface portions of the storage means.
Collection means (1c_-11c _-2) And mounting the wireless terminal mounted in the storage means
Mounting means (10, 10a) having a single directivity and the directivity axis having the directivity axis.
And a measurement antenna (11) intersecting the two planes
And attached to one end surface of the storage means, the measurement antenna
A high frequency terminal (3) connected to the
Shield box to collect. 2. The dipole antenna (1) parallel to the transmitting / receiving antenna,
1a) and 2 parallel to the dipole antenna and crossing each other
The shield box according to claim 1, wherein the shield box is composed of a corner reflector (11b) composed of two flat plates (11b _-1 , 11b _-2 ).