Learn how to waterproof the base station interface in one article

Most of today's base stations are distributed base stations, consisting of BBU, RRU and antenna feed system (also commonly known as antenna). BBUs are generally installed in indoor computer rooms or outdoor cabinets, and there is no need for waterproofing. The outer casing of the RRU and the antenna itself are both waterproof, so there is no problem with being exposed to wind and rain. As for the interface between the BBU and the RRU, one end of the interface is indoors and the other end of the interface is within the RRU's maintenance window, so they are not exposed to rain.

Therefore, what needs to be focused on daily waterproofing is the interface connecting the RRU and the antenna. That is, the ANT interface of the RRU and the ANT interface of the antenna.


Before introducing the specific waterproofing methods, let me first educate you on what interfaces RRU generally has. The picture below is a representative appearance of an RRU.

So how are these interfaces waterproofed? Let’s introduce it in detail below.

ANT interface waterproof solution

The ANT interface is the most numerous interface on the RRU. Its function is to connect to the antenna. Currently, there are two mainstream waterproof solutions.

Cold shrink tube waterproofing solution The cold shrink sleeve is actually an elastic tube. When the plastic spiral strip supported inside the tube is pulled out, the tube shrinks by elastic retraction force and is tightly wrapped around the outside of the cable interface. The seal is tight and can play a role. Waterproof, moisture-proof and dustproof. The steps for waterproofing the RRU's ANT interface using cold shrink tubing are as follows.

1. Put the cold shrink tube on the cable to be installed, and then install the cable connector to the ANT interface of the RRU. 2. At a distance of about 130 mm from the root of the RRU (that is, about the length of a cold shrink tube), evenly and overlappingly wrap 3 turns of waterproof insulating tape to expand the wire diameter.

3. Push the cold shrink sleeve to the root of the RRU, and spirally pull the core rope of the cold shrink sleeve downward around the cable. While pulling the core rope, push the cold shrink sleeve toward the root of the RRU until the cold shrink sleeve is in place. Shrink tightly near the base of the connector, and the waterproofing is completed.

The so-called "1+3+3" waterproof treatment refers to the waterproof method of "one layer of insulating tape + three layers of waterproof tape + three layers of anti-UV tape" (1+3+3). The purpose is one layer of insulating tape (to prevent leakage), three layers of waterproof tape (waterproof), and the outermost three layers of anti-UV tape (to protect the waterproof tape and prevent sun aging and loss of waterproofing).

In actual applications, the ANT interface of most antennas uses the "1+3+3" waterproof method.

When handling, first remove dust, grease and other debris from the cable connector. Then wrap one layer of insulating tape, three layers of waterproof tape and three layers of UV-resistant tape in sequence. Finally, tie both ends of the tape firmly with black anti-UV ties to prevent the glue from opening.

In order to achieve the best waterproof effect, the way of wrapping the tape is also very particular.

1. Wrap a layer of insulating tape:

According to the direction of tightening the joint, wrap a layer of electrical insulation tape on the joint in a semi-overlapping manner from top to bottom, with the upper layer of tape covering 1/2 of the lower layer of tape.

2. Wrap three layers of waterproof tape:

First, stretch the waterproof tape evenly. Then, wrap three layers from bottom to top, top to bottom, and bottom to top according to the direction of tightening the joint. Note that the upper layer of tape covers 1/3 of the lower layer of tape to prevent rainwater leakage. Do not cut the tape during wrapping. After the winding is completed, you should hold it repeatedly with both hands to ensure that the tape, cables and cable joints are firmly bonded.


3. Wrap three layers of anti-UV tape:

The wrapping direction is the same as wrapping waterproof tape. Just use natural strength to stretch and wrap the UV-resistant tape. Note that the upper tape covers 1/2 of the lower tape.

4. Fix both ends of the tape:

Be careful to keep 3 mm of excess tie tape at the tie point to prevent the tape from expanding in hot weather.


If the antenna equipment uses an electrically adjustable antenna, the waterproofing treatment method is slightly different. The electrically adjustable antenna is generally connected to the AISG interface of the RRU through the RCU electrically adjustable antenna controller. On the RRU side, AISG cables do not need to be waterproofed.

On the ESC antenna side, different waterproof treatments are used at both ends of the RCU:

1. The connector where the RCU connects to the ESC antenna is waterproof using the “1+3+3” method mentioned above.

2. Wrap two layers of anti-UV tape at the joint where the RCU connects to the AISG cable. Note that the first layer of UV-resistant tape should be wound from top to bottom, and the second layer should be wound from bottom to top. In other words, the outermost layer of tape must be wrapped from bottom to top to prevent water droplets from penetrating.

Unused interface waterproof solution

Unused interfaces of the RRU also need to be waterproofed. The protective measure is to wrap the dust cover with two layers of UV tape.

1. Check whether unused interfaces have dust covers.

2. Wrap two layers of UV-resistant tape. According to the direction of tightening the joint, the first layer should be wrapped from top to bottom, and the second layer should be wrapped from bottom to top. After wrapping, it should be flush with the bottom surface of the cover. Tie the edges of the tape tightly with zip ties.

The above are the main waterproof measures for each cable interface location. In addition, the editor also summarized some daily waterproofing precautions for everyone~

When the equipment is stored in the warehouse, try not to remove the packaging that protects the equipment. If the packaging of the device is removed, the device is at risk of getting wet and the device must be powered on within 72 hours.

You should also pay attention when powering off the equipment for maintenance, and try not to power off the equipment for more than 72 hours.