Earth Station Antenna System

As you can learned from previous blog that we shipped out 1 set of 6.2m earth station antenna  in this August to North European client in satellite communication industry. Now client had completed installation some days ago and backed to us some photos. How efficiency they are!

 

6.2m earth station antenna in Europe

In this modern era of wireless communication, earth station antenna system is playing a prominent role in satellite communication. In this article, we will have a thorough introduction for earth station antenna system. Besides its main compositions of antenna, we also cover about the operation and maintenance in detail.

The earth station antenna is an important equipment of the satellite ground station, which is a device for the radio equipment system to realize energy conversion, and responsible for signal transmission and reception of electromagnetic waves. Before we talk about earth station antenna, let us understand a few parameters about antenna firstly.

The earth station antenna is the input and output channel of the radio frequency signal of the earth station. The performance of the antenna system directly affects the performance of the entire communication system. Therefore, the antenna system parameters usually meet the following basic requirements to achieve good performance.

• High gain value

The higher gain value, the stronger EIRP under the condition of the same output power. In addition, when the noise temperature of the receiving system is the same, the antenna gain is high, and G/T value is also high. Therefore, no matter from the perspective of receiving or transmitting, high gain is an important factor affecting the performance.

• Narrow beam width and low side lobe level

This is mainly considered from the electromagnetic compatibility (anti-interference) between adjacent satellite communication systems and between the ground microwave relay communication system, and only meet this requirement, the satellite communication system and the ground microwave relay communication system in order to work well with each other.

• Broadband

Each satellite is composed of dozens of transponders. When the antenna is aligned with the satellite, it is required to meet the working frequency of all transponders, and the antenna (transceiver equipment) should have high gain and well-matched features.

• Low loss

The feeder system connected to the antenna should have the characteristics of low loss, wide frequency bandwidth and large isolation between Rx. and Tx. channels. The transmitting channel must also be able to withstand the maximum output power of the transmitter.

• Low noise temperature

The antenna system requires a better receiving capability, which requires a lower temperature noise of the receiving system. In addition to reducing the feeder loss, it is also necessary to reduce the equivalent noise temperature Tα.

• Good rotation capability

The antenna beam direction is required to be able to change in a wide range, the earth station antenna should have a strong rotation performance, with an azimuth angle of 0°- 90° (limit movement) and an elevation angle of 0° to 90°.

Due to about 36,000km far between the earth station and the satellite, most earth station antenna system adopt a parabolic reflector antenna with good radiation pattern, high gain, and convenient long-distance transmission of radio waves in order to ensure the effective transmission of the signal. At present, the satellite communication antennas used in broadcast and television transmission mainly include three types

of dual-reflector antennas like Cassegrain, Gregorian, and ring focus . This 6.2m earth station antenna is ring-focus type earth station antenna with excellent performance and can meet the above requirements.

In general, earth station antenna system mainly includes antenna and tracking &servo system, RF transceiver subsystem, modulation and demodulation subsystem, baseband system, monitor subsystem, interface subsystem and power subsystem. Here we focus on the first 4 parts below.

 

Diagram of ground station system

① Antenna and tracking &servo system

This is about receiving and transmitting the satellite signal, drive and control antenna to rotate manually or motorized.

Uplink/Transmit: Amplify the RF signal output by HPA through the antenna and transmit it to the satellite

Downlink/Receive: Receive the RF signal from satellite

Track& servo: Control antenna to align satellite

② RF transceiver subsystem

About frequency conversion and amplification of the signal;

Uplink/Transmit: Up-convert the modulated signal to the communication frequency (C@4/6G, Ku@12/14G, Ka@30/40GHz), and transmit it to the satellite through the antenna after being amplified by HPA

Downlink/Receive: The signal received from the antenna is first amplified by the LNA, then down-converted to the demodulation frequency (usually L band or 70/140Mhz), and sent to the demodulator for demodulation;

③  Modulation and demodulation subsystem

Can realize the modulation and demodulation of baseband digital signals

Uplink/Transmit: Modulate the baseband’s digital signal to intermediate frequency (70/140MHz or L frequency band) and send it to the upconverter

Downlink/Receive: Demodulate the intermediate frequency signal output by the down-converter into a digital baseband signal, and send it to the baseband subsystem.

④ Baseband subsystem: Baseband digital signal processing;

The ground station system can be applied in such scenes.

After the antenna is completed, it is necessary to perform regular maintenance, inspection to ensure the normal operation of the antenna system, ensure the safety of satellite earth station service transmission, and help increase the service life of the antenna. The maintenance of the antenna system mainly includes the following.

Maintenance type Maintenance items	Clearing	Fastening	Lubrication	Anti- corrosion	Inspection or Change
Feed film					Inspect periodically,if cracked or deformed, replace it in time. Check once a year.
Feed	√				Periodical inspection, clear exotic matters to insure deciccation inside.
Reflector	Remove snow in time in snowy days.			√	Inspect periodically,remove rust and repair paint in time. Check once a year.
AZ/EL lead screw cover					Inspect periodically, and change it in time if there is ageing or damage.
AZ/EL lead screw			Use lubrication oil in time accordingly.		Inspect periodically
Left&right Support lug			Use lubrication oil in time accordingly.
King post mounting					Inspect periodically, and remove rust and repair paint in time.
Foundation anchor blots	Periodical dedusting	Fasten it in time accordingly.			Inspect periodically
Standard parts		Fasten it in time accordingly.			Inspect periodically, change it in time if damaged.
Connection of metal components		Fasten it in time accordingly.			Inspect periodically
Corrossion of metal components				Remove rust and repair paint in time accordingly.
Waveguide (if possible)					Inspect periodically if it is geasing too often.
Antenna grounding (if possible)					Periodical inspection
Beacon/controller (if possible)	Periodical dedusting				Inspect periodically to insure dissipation.
AZ/EL drive motor&reducer (Motorized antenna applicable)			Use lubrication oil in time accordingly.	√	Inspect periodically
AZ/EL limit switch (Motorized antenna applicable)		Fasten it in time accordingly.	Use lubrication oil once a year accordingly.	√	Inspect periodically, and change it in time if necessary.
ACU&ADU (Motorized antenna applicable)	Periodical dedusting				Inspect periodically, remove dust on the cooling fan in time and change it if necessary.
Drive motor power cable (Motorized antenna applicable)		Fasten it in time accordingly.			Inspect periodically, and change it in time if there is ageing, damage.

 

The above is a summary of the maintenance method of the antenna system based on the maintenance experience. You can appropriately adjust the frequency according to actual conditions to ensure the stable operation of the antenna system.

That’s all about the ground station introduction, if you have anything interested, please WhatsApp us directly or via email at sales@antesky.com freely. Thanks in advance.

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