Patented Fabric based Absorber LPAFA Series

LPAFA Absorber is a novel radio-wave absorbing material for anechoic chamber. Compared with PU absorber, this non-woven fabric based absorber material has better performance in power capacity, fire-retardancy and environmental protection than polyurethane absorbers. It meets the requirements of NRL Report NO 8093 Test 1, 2 and 3 and other related standards. LPAFA absorber has the same reflectivity performance as conventional PU absorber, but it has no unpleasant smell, powder that falls off, nor drooping tips in the long-term use. It is also clean and humidity resistant. Developed in 1999, this type of absorber has been successfully used in over 100 anechoic chambers for radar, satellite, wireless communication and antenna measurement and EMC test application.

The design concept of adopting pyramid absorber in anechoic chamber is first proposed by Tiley JW and he won the U.S. Patent [1] in March,1949. For over 50 years, with the requirement of high-performance radar development and technology advance, PU

absorber immersed with Carbon has achieved high absorption rate, but it could not withstand several kilowatts per square meter of microwave power irradiation. Therefore, it could not meet the requirements of developing & producing modern weapons. In 1999, Nanjing Lopu developed a novel absorbing material, LPAFA absorber, which is made of non-woven fabrics and special mineral. LPAFA absorber maintains the same absorbing properties as PU absorber, but LPAFA absorber has better performance in power capacity, fire-retardancy and environmental protection and etc. Since developed, it has been applied in over 100 various types of anechoic chamber, with application area of over 100,000 square meters. Such LPAFA absorber has been widely applied in aerospace, electronics, IT, RF and other fields.

1. LPAFA absorber physical properties

The LPAFA pyramid absorbing material is a type of electric loss absorbers, and pyramid structure is applied to perfectly match radio waves. With vertical incidence its wave impedance gradually changes from 377Ω to 2Ω, avoiding reflection on the absorber's

surface. For those radio waves entering into the absorbing material, with its good electrical conductivity, such absorbing material rapidly transforms the electromagnetic energy to Ohm energy, thus to attenuate the radio waves. Assume the reflectivity of absorber is R, when its thickness wavelength ratio t/λ=0.2, R=-14dB; when t/λ=1, R=-31dB; when t/λ=7,R=-50dB.

2. LPAFA absorber safety performance

Such absorber has good fire-resistant performance, as it is made up of inorganic substances. Tested according to GB/T2406-93《Plastic combustion performance test method, the oxygen index method》, with oxygen index over 60%, it can meet the requirement of GB8624-1997《Flammability of building materials classification method》, it is B1 Flame retardant materials. It can withstand high-power irradiation. Under the microwave power irradiation of below 15kw/sqm, it won't take any cooling facilities.The testing of flame ignition & spread, conductance and Internal heat, it shows its performance is superior to the requirements of test I voltage-resistant, test II difficulty of flame ignition and propagation, test III flame-resistant test of Navy laboratory report NRL8093 (1977). Therefore, no matter the irradiation of strong lighting, strong current,flame and strong microwave, it won't bring combustion. It is absolute safety materials, and it can be used in microwave anechoic chambers,, without any fire worries. Adopting such absorber can greatly simplify the anti-fire system in the anechoic chambers. It has been passed the review of some anti-fire safety departments.

3. LPAFA absorber environmental performance

Tested according to GB/T14677-93 "air emission monitoring and analysis methods", chamber's inside health environment is able to meet the Chinese living standards. Such absorber won't pollute the environment, even scrapped in the future. It is an environmental protection type absorbing materials. It has stability chemical properties, no odor, no harmful gases released, no powder off, non-fade phenomenon, it also doesn't absorb moisture,with cleanliness degree up to 100,000.

4. LPAFA absorber's structure and properties

It can meet more than 10 years' service life, and the absorber won't bend, and shed within 10 years' service life. The absorber has neatly arranged pyramid, with good visual effects and light reflective. It also has flush bottom, no residue, clean appearance, uniform color, as well as smooth feeling, without fade phenomenon. During the warranty period, there is no cracks, no discoloration, no deformation. Such absorber can be applied in antenna far-field measurement microwave anechoic chamber, far-field measurement microwave anechoic chamber, RCS measurement microwave anechoic chamber, and EMC measurement anechoic chamber, and etc (If left figure, it is the first anechoic chamber we adopted such LPAFA absorber, which was built in 2000, achieved good economic and social benefits. The largest anechoic chamber (In right figure) adopting such LPAFA absorber was built in 2005, with size 54m *10.8m * 10.90 (L*W*H), it is built for antenna far-field measurement. The standard installation of LPAFA absorber is to hang on the metal surface. It is maintenance free, will not drop off for long time, can be put into use immediately after installation without waiting for the glue evaporating, and is easy to replace. The installation of absorbers for the four sides and ceiling is to hang on the keel backing.

For more details performance and certification information, please contact lopu.

We mainly engaged in product R&D, system design and project contracting in the fields of Antenna measurement system and Anechoic Chambers as well as 5G telecom related testing and servies.

As a high-tech enterprise,we have been awarded a number of national high-grade qualifications, and has passed authentication of ISO9001 Quality Management System, ISO14001 Environmental Management System, and OHSAS 18001 Occupational Health and Safety Management System.

Due to excellent performance and good service, we have been one of the indispensable co-partner of the government, IT has undertaken and accomplished series of major projects in many significant missions including National-level Professional Anechoic Chambers, Largest Integrated Testing Anechoic Chamber in Asia and so on. Besides the outstanding achievement in China, we had exploited the international market actively and had exported the products to more than 80 countries and regions around the world. we also undertook some foreign aid projects from the Ministry of Commerce of the People-s Republic of China and achieved remarkable success.

We look forward to cooperating with the friends all over the world, making mutual benefit, and creating a bright future.