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Fiberglass radomes for Andrew Corporation and Hitachi

1. Fiberglass radome for Andrew Corporation

Product: Fiberglass radome
Customer: Andrew Corporation (In the United States and China)
Cooperation time: Since 2011
Radome application: Military and commercial radomes in Stadium, Base station, and Maritime satellite.

1.1 Fiberglass radome introduction

The radome (the portmanteau of radar dome) is a structural weatherproof enclosure for the radar system. Radomes protect the antenna, for example, radomes for rotating antennas have a function of reducing drag. They can protect the antenna from the wind and other stuff in the air. There are many construction materials for them, such as fiberglass, PTFE, etc. Among all radome materials, the fiberglass is suitable for a variety of complex environments. In general, its service life is 30 years. And it has many advantages of an easy FRP installation process, low cost, corrosion and moisture resistance. You even don’t need to spend time on maintaining it. Thus, you can use it to protect the radar antenna and dish antennas and play its biggest role. As a result, fiberglass radomes have been widely used in military and commercial industry.

1.2 Fiberglass radome application

The 16th Asian Games in 2010 was held in Guangzhou. And Guangzhou is the “Beautiful Flower City” in China. The Guangzhou Asian Games Comprehensive Gymnasium includes gymnastics hall, billiards hall, squash hall and Guangzhou Asian Games Historical Museum. It is the largest venue for the Guangzhou Asian Games in 2010, also one of the key venues for the competition. DOFRP is one of the top radome manufacturers in China. Finally, we have the honor to become the only supplier of large antenna radomes for the Asian Games Stadium.

Radome dimension: 1359*852*140 mm
Package dimension: 1480*960*240 mm
Radome material: Fiberglass reinforced plastic
Radome weight: 30.5 kg
Lifting pole dimension: 75-110 mm
Stent type: Fixed fastening clip
Working Humidity: 95% RH@+30
Working temperature: -40℃ to +70℃
Ice resistance: Not be damaged within 10 mm
Wind resistance: The working wind speed is 114 km/h, the extreme wind speed is 200 km/h.
Rain resistance: 140 mm/h

1.3 Problems and FRP solutions

1.3.1 Deformation and transmission

The customer needs that the largest dimension of radomes is 1800*1800*2 mm. And this kind of radome really has a big span. At the same time, the thickness of this fiberglass radome is only 2.0 mm. After confirming the customer’s needs, we conducted many discussions, carried out various surveys on fiberglass materials. Through several internal development tests and verification, we provided a satisfactory turnkey solution. And it meets the Andrew Corporation need of transmission loss 2.0. In the meanwhile, we modulated the reinforced material by ourselves. Finally, we succeed in solving the problems of deformation and collapse.

1.3.2 Thickness and strength

The required thickness of the entire radome antenna must be 2.0 mm. We made professional FRP work instructions, technicians followed and guided the work on site during the whole fiberglass radome manufacturing process. In the meantime, we measured the FRP radome’s thickness with the precise thickness gauge imported from Japan to meet their need. As for the strength, we first use the high strength fiberglass resin type and high quality reinforced material while choosing construction materials. Also, we ensured the solidification of the radome antenna in a reasonable range. Even more, we did a strength failure test for each batch of fiberglass radomes to verify and guarantee the high strength.

1.3.3 Gap and hole

There may be a gap between the outer radome cover and the baseboard during the assembly process. Of course, we control each manufacturing process detail during operation. Our technical engineer designed and developed professional fixtures to punch a hole, check and verify the hole site. Also, we help to solve the water leakage problem in the gap which they worried about. So far, we have not got any complaint from them.

During the fabrication, we not only fully cooperated with the client’s emergency delivery date, but also provided fiberglass radome with good RF performance. Also, we signed a privacy policy and keep it a secret before it launches. Thus, the Andrew Corporation highly praised our services. Since the Asian Games, they have been purchasing fiberglass radomes from us and exporting a large number of our AFC radomes to the Australian region. Our fiberglass radome used for the marine application can even resist Grade 12 typhoon.

Mr Yamamoto, a Japanese who has over 20 years experience in FRP industry, is now in charge of fiberglass radome. As he said:
“It’s a key for us to choose different GRP material according to the microwave transmittance and permittivity.”

2. Omnidirectional antenna radome for Hitachi

Product: Fiberglass Omni directional antenna radome
Specifications: φ 50 mm-φ 680 mm
Customer: Hitachi, Japan’s top three antenna factories
Cooperation time: Since 2006

2.1 Radome antenna introduction

Do you know what the Omnidirectional antenna is and how about its space frame? In the horizontal direction, the Omnidirectional antenna has a 360° all uniform radiation. In general, we call it a non-directional antenna. And on the vertical direction, it appears as a beam of a certain width. As we all know, the smaller the radiation lobe width is, the transmission gain of the antenna system will be greater. Omnidirectional antennas for mobile communication system are normally used in the large suburban area system station type, and they have a large coverage area.

Related parameters of Omnidirectional antennas:
Antenna gain: 14 dBi
Standing wave ratio: Less than 1.92
Input impedance: 50 Ω
Largest power: 1W
Splice: REVERSE SMA
Cable length: 1 meter

2.2 Problems and FRP solutions

The whole radome antenna manufacturing process includes the radome design, prenatal review, making the FRP mold drawing, producing metal molds, and sample production. After that, we also provide other services including the sample detection, quality insurance, and so on. Whether it’s technology or credential, as a leading fiberglass radome manufacturer, we can provide help. We have thoughtful services and have solved a lot of knotty problems one by one for our customers in many aspects.

2.2.1 Fiberglass mold making

Hitachi has a quite strict requirement of the radome antenna size’s precision. The tolerance of the radome’s inner diameter must be within ±0.1 mm. Because we use the filament winding process to produce the fiberglass radome. As we all know, the traditional fiberglass winding tube molds have a mold release slant angle. The customer requires the tolerance of the fiberglass radome to be ±0.1 mm. in the same way, it’s impossible to reserve the slant on the FRP mold. For the 6 meters long mold, how can we release the mold without deviation? DOFRP technical team tried, calculated and tested again and again, and finally solved this problem.

2.2.2 High strength

No matter where the radome is used, in a weather radar, array radar or for satellite communications, it’s outdoors. As we all know, Japan is an Island country. It’s certainly necessary to have a special need of the radome strength. In the weather radar, the radome protects the radar from the diverse electromagnetic signal and meteorological interference. Now, our radomes can resist the Grade 12 Typhoon and temperature from -45℃ to 120℃, and their service life can be up to over 30 years.

After the discussion and research of our engineers and the customer, we finally find a solution. If we control the glass fiber content of the fiberglass reinforced plastic within 68% to 73%, the strength need can be reached in theory. However, the failure of the first test proved that it’s not enough. After a series adjustment by our technical engineers, we finally make the high strength come true.

2.2.3 Zero Impurity

The antenna system does not allow the magnetic metal or other organics in the radome antenna. Because they will have an effect on the strength of the transmit signals. Before the storage of raw materials, we must confirm the quality, and do not allow any foreign matters mixed in. Before the production of fiberglass radomes, besides the 5S management, we strictly need to use clean measuring tools and wear the disposable gloves every time. If there are any foreign matters in the glass fiber production process, we will pick them out in time. Also, we use the PET film to wind up the radome for final protection after the product is completed. The next day, we repeatedly check the surface condition and the inner wall of the fiberglass radome to confirm the quality.

2.2.4 A significant breakthrough

Most noteworthy, DOFRP has made a breakthrough. We have not only achieved the uniformity of 2 mm FRP thickness but also controlled the tolerance within ±0.1 mm. It broke through the thickness and tolerance that cannot be achieved in the composite industry for the filament winding process. As a protective enclosure for the antenna system, with the even thickness, it makes the whole radome antenna have a better wave transmit performance.