Patent Application
20110298673
1. Technical Field
The present disclosure relates to full anechoic chambers and, particularly, to a full anechoic chamber that can be used for carrying out both a radiation emission (RE) and a radiation susceptibility (RS) tests.
2. Description of Related Art
Generally, electrical products such as cell phones need to be tested for electro magnetic compatibility (EMC) in a full anechoic chamber under the standard number 22 of the International Special Committee on Radio Interference (CISPR22). The EMC tests typically includes an RE tests and an RS tests. However, a typical full anechoic chamber is usually designed for either RE tests or the RS tests. That is, a typical full anechoic chamber designed for the RE tests can't be used for the RS tests, and vice versa. Thus, there are required two full anechoic chambers respectively for the RE tests and RS tests, thereby increasing cost.
What is needed, therefore, is a full anechoic chamber which can ameliorate the above-described limitations.
Embodiments of the present disclosure will be described next with reference to the accompanying drawings.
Referring to
The full anechoic chamber 100 is generally a hollow cuboid chamber and includes a first sidewall 101, a second sidewall 102 substantially perpendicular to and connected to the first sidewall 101, a third sidewall 103 connected to the second sidewall 102 and opposite to the first sidewall 101, a fourth sidewall 104 connected to the first and third sidewalls 101, 103 and opposite to the second sidewall 102, a top wall 105 substantially perpendicular to the first sidewall 101 and the second sidewall 102, a bottom wall 106 opposite and parallel to the top wall 105, an antenna holder system 30, and a loading table 40. The antenna holder system 30 and the loading table 40 are oppositely positioned on the bottom wall 106. A reference plane AA extending along a direction substantially parallel to the second and fourth sidewalls 102, 104 and through the centers of the first sidewall 101 and the third sidewall 103 is defined. The reference plane AA is substantially perpendicular to the top and bottom walls 105, 106. The full anechoic chamber 100 is a symmetrical configuration about the reference plane AA. The full anechoic chamber 100 also includes a shielding door 1012 installed in the first sidewall 101.
In order to effectively absorb radio wave, the inner surfaces of the first sidewall 101, the second sidewall 102, the third sidewall 103, the fourth sidewall 104, the top wall 105, and the bottom wall 106 are all covered with a layer of a first radiation absorbing material. In the present embodiment, the layer of the first radiation absorbing material includes an array of plates made of ferrite tiles of SN-20 made by the SAMWHA CAPACITOR GROUP as shown in
The first sidewall 101, the second sidewall 102, the third sidewall 103, the fourth sidewall 104, and the top wall 105 are partially covered with a layer of a second radiation absorbing material on the first radiation absorbing material and respectively formed five radio wave absorbing areas 1011, 1021, 1031, 1041 and 1051. In the present embodiment, the layer of the second radiation absorbing material includes an array of tapered rectangular columns made of carbon-loaded urethane foam of VHY-12-NRL made by EMERSON & CUMING MICROWAVE PRODUCTS N.V as shown in
The bottom wall 106 forms a radio wave absorbing area 1061. Concretely, the radio wave absorbing area 1061 comprises a middle absorbing area 1062 and two side absorbing areas 1063 positioned at the two sides of the first absorbing area 1062. Each side absorbing area 1063 is covered with a layer of a third radio absorbing material. The middle absorbing area 1062 is covered with a layer of a fourth radiation absorbing material. In the present embodiment, the third radio absorbing material includes an array of pyramids made of carbon-loaded urethane foam of VHP-8-NRL made by EMERSON & CUMING MICROWAVE PRODUCTS N.V as shown in
Referring to
An antenna 301 is detachably held by the antenna holder system 30. The antenna 301 has a symmetrical structure about a center axis 3011 thereof. The center axis 3011 of the antenna 301 is parallel to the bottom wall 106 and forms an acute angle α relative to the reference plane AA. The angle α is from about 5 degrees to about 10 degrees. In the present embodiment, the angle α is about 8 degrees.
The antenna 301 can be selected from a double-ridged waveguide horn antenna for the RE tests in which the radio frequency is from about 1 GHz to about 6 GHz, a microwave horn antenna for the RS tests in which the radio frequency is from about 1 GHz to about 3 GHz, and an ultra broadband antenna for the RS tests in which the radio frequency is from about 80 MHz to about 1 GHz, according to the type of tests to be carried out. In the present embodiment, each of the three types of antenna 301 respectively has a glass fiber tube 302 having a corresponding predetermined length. The glass fiber tube 302 is configured for conveniently mounting the antenna 301.
The loading table 40 is configured for loading an equipment under test (EUT) and has a pivot axis 401 positioned on the reference plane AA. When using the double-ridged waveguide horn antenna to carry out the RE tests, the EUT is loaded on the loading table 40, and the distance in a horizontal direction between the EUT and the center 3013 of the double-ridged waveguide horn antenna is about 3 meters, and the loading table 40 rotates about the pivot axis 401 and brings the EUT to rotate. When using the microwave horn antenna or the ultra broadband antenna to carry out the RS tests, the distance in a horizontal direction between the EUT and the front end 3012 of the microwave horn antenna or the ultra broadband antenna is about 3 meters, and the loading table 40 needn't to be rotated.
In order to satisfy the standard of the CISPR22, a site voltage standing wave ratio (SVSWR) of the full anechoic chamber 100 must be lower than 6 dB.
After setting the angle α as 8 degrees, the following tests for verifying whether or not the full anechoic chamber 100 satisfies the RS tests conditions are carried out. First, take a uniform field area (UFA) measurement in which the radio frequency is form about 1 GHz to about 3 GHz, the size of the UFA is 1.5 m×1.5 m. The following table 2 shows the result of the measurement.
From the table 2, it is found that, the max absolute differences are 9.4 dB and 9.0 dB respectively in horizontal and vertical directions and both greater than a standard value of 6.0 dB defined in the standard of the CISPR22. The facts of the field identify is low in the four corner of the UFA and the beam width of the antenna is not enough cause the max absolute differences being greater than 6.0 dB. It is needed to decrease the area of the UFA.
Then take a UFA measurement in which the radio frequency is from about 1 GHz to about 3 GHz, the size of the UFA is 1 m×1 m. The following table 3 shows the result of the measurement.
From the table 3, it is found that the max absolute differences are 5.8 dB and 5.6 dB respectively in horizontal and vertical directions and both smaller than 6.0 dB of the standardization CISPR22. Thus, it satisfies the standard CISPR22.
Then, take a UFA measurement in which the radio frequency is from about 80 MHz to about 1 GHz, the size of the UFA is 1.5 m×1.5 m. The following table 4 shows the result of the measurement.
From the table 4, the max absolute differences are 4.8 dB and 5.7 dB respectively in horizontal and vertical directions and both smaller than 6.0 dB of the standardization CISPR22. Thus, it satisfies the standard CISPR22.
The full anechoic chamber 100 mentioned above can used for RE tests in which a working frequency is from about 1 GHz to about 6 GHz and RS tests in which a working frequency is from about 1 GHz to about 3 GHz.
It is to be understood, however, that even though numerous characteristics and advantages of the disclosure have been set forth in the foregoing description, together with details of the structures and functions of the embodiment(s), the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201010188679.3 | Jun 2010 | CN | national |
