Radiation Emission Test
Radiation emission test is to measure the radiation disturbance field intensity of EUT propagating through space. It can be divided into magnetic radiation, electric field radiation, the former is for lamps and induction cookers, the latter is widely used. In addition, home appliances and power tools, AV products auxiliary equipment have power radiation emission requirements (known as disturbance power).
2. Radiation emission (RE) test standard:
|Category||National Standard||IEC Standard|
|Household appliances, electric tools and similar appliances||GB4343.1||CISPR14-1|
|Information technology equipment||GB9254||CISPR22|
|Sound and television broadcasting receivers and related equipment||GB13837||CISPR13|
|Electrical lighting and similar equipment||GB17743||CISPR15|
|Industrial, scientific and medical (ISM) RF equipment||GB4824||CISPR11|
3. Radiation emission (RE) test method:
1) Radiation emission testing instruments and equipment:
(a) Electric field radiation: receiver (less than 1G), spectrometer (more than 1G), anechoic chamber, antenna (below 1G generally using a combination of two cones and logarithmic periods or a broadband composite antenna, 1G or more horn antenna);
(b) Magnetic field radiation: receiver, three-ring antenna or single-ring remote antenna;
c) Disturbance power: receiver, power absorbing clamp.
The receiver conforms to the requirements of CISPR16-1-1, the antenna and the field follow the requirements of CISPR16-1-4, and the absorber follows the requirements of CISPR16-1-3.
2) Radiation emission test arrangements:
(a) Electric field radiation: it also has two types, desktop and floor type, same as conducting emission (As the results of radiation emission are particularly closely related to the product layout, it need to arrange the samples under test include products, auxiliary equipment and all cables strictly in accordance with the standard);
(b) Magnetic field radiation: three ring antennas of different sizes have limits to the maximum size of the EUT that can be tested. Take an annular three-ring antenna with a diameter of 2m as an example, EUT with a length less than 1.6 m can be tested in the center of the three-ring antenna. In CISPR11, the electromagnetic furnace over 1.6 m is measured with a single loop antenna of 0.6 m diameter 3m away, and the lowest height is 1m
(c) Disturbance power: there are two types, table type and floor type. For table type, the equipment is placed on a 0.8m non-metallic table at least 0.8m away from other metal objects (usually the metal interior wall of the shielding chamber, this distance is required to be at least 0.4m in CISPR14-1). For ground type, equipment is placed on a nonmetallic support of 0.1 m, the tested cable(LUT) is arranged on the rail of the power absorber clamp with a height of 0.8m and length of 6m, the absorber clamp is set around the cable and the current transformer is oriented towards the equipment under test. If the equipment under test has other cables, they can either be disconnected if not affecting the function, and the unbreakable can be isolated by ferrite absorber.
4. Radiation emission test process:
a) 30MHz-1GHz electric field radiation: conducted in the half-wave anechoic chamber, the EUT rotates 360 degrees with the turntable, and the antenna rises and falls up and down at a height of 1-4m to find the maximum radiation. The results are expressed as QP values. Both vertical and horizontal antenna polarization directions are measured.
b) Electric field radiation greater than 1G: ITE equipment with operating frequency greater than 108MHz and ISM equipment over 400MHz need to be tested, using spectrum analyzer at a 3m site. Test method of ITE equipment is basically the same as 30MHz-1GHz., the result is expressed by Peak and AV value. It is a little different for ISM products which need to be measured in the full anechoic chamber, the antenna is the same height as the product, no lifting, the turntable still rotates to find the maximum radiation, till the measuring receiver reaches the same value. Record the input power of the alternative antenna B, that is the shell radiation power of the EUT. Antenna selection is based on the test frequency.
c) Magnetic field radiation: magnetic radiation measurements using a three-ring antenna, in which samples are placed in the center of the antenna and X/Y/Z in three directions to get test result of magnetic field radiation respectively. When a single small ring antenna is used, the antenna is placed vertically on the ground, and the lowest part is higher than 1m above the ground. Because it is measured in near field and considering the reflection of the ground, the measured value reflects the horizontal and vertical magnetic field components of EUT.
<span “=””>d) Disturbance power: all cables of the equipment longer than 25cm (including auxiliary cables) need to be tested. Because the disturbance at different frequency points in 30-300MHz is distributed in the form of standing wave in the cable under test. Therefore, it is necessary to pull the power absorber along the rail in order to find the position of the maximum disturbance power at each final frequency point (approximately half the wavelength of the device).