Sizing a Fixed Satcom Earth Station Antenna for an LNG or Refinery Site

Sizing a Fixed Satcom Earth Station Antenna for an LNG or Refinery Site

The right earth station antenna for an LNG terminal or refinery is the smallest parabolic dish that meets four conditions. It must close the return link (site to hub) at the plant's agreed availability in its local rain climate. It must stay within the satellite operator's off-axis emission limits. It must also have a clear view of the satellite and mount outside the classified hazardous areas. Diameter is the output of that calculation, not the starting point. StarWin builds fixed earth-station antennas from 1.2 m to 16 m across L, S, C, X, Ku and Ka band, and satellite operators including SES, Hispasat and Arabsat have qualified its antennas and terminals.

TL;DR

·       Size for the uplink first. Process plants push CCTV, historian and SCADA data outward, so the return link often sets the diameter.

·       Band choice moves the answer most. C-band tolerates heavy rain but needs a bigger dish. Ka-band is compact but fades hardest.

·       A small dish cannot simply run a bigger amplifier. Its wide beam spills energy onto neighbouring satellites.

·       The site can veto the size. Hazardous zones, flare stacks, process columns and wind load can all overrule a technically correct diameter.

·       Split the traffic. Safety telemetry belongs on a separate path, so a rain fade never blinds the control room.

About the Author: Written by StarWin's technical team in Chengdu. StarWin reports fixed earth-station antennas from 3.7 m to 13 m delivered across Africa, the Middle East, Southeast Asia, Europe, Latin America and Central Asia, including for teleport and satellite-operator customers.

What actually determines antenna size for an LNG or refinery site?

The size comes from a link budget, which balances what the satellite delivers at your location against what your traffic demands. The inputs are:

·       Traffic, by direction. A plant often sends more than it receives: camera feeds, process historian data, DCS replication and voice.

·       Satellite performance at the site. The operator supplies the EIRP and G/T contours for the beam covering you.

·       Modulation and coding. The baseband terminal's encoder, decoder, modulator and demodulator decide how efficiently each hertz is used. More efficient coding lets a smaller dish carry the same traffic, but it needs a cleaner signal.

·       Availability target and rain climate. Rain loss is modelled for the site's coordinates, usually with the ITU-R rain attenuation method.

·       Margins. Allow for pointing loss, component ageing and traffic growth.

Gain scales with the square of the diameter: G = η(πD/λ)². A dish works like a bucket catching radio energy, and the catching area grows with the square of its width. Doubling the diameter therefore quadruples gain, adding about 6 dB.

Sizing sequence:

1.       Split traffic into "must never drop" and "can degrade".

2.       Request footprint data and the approved antenna list from the operator.

3.       Run the return-link budget at worst-case rain.

4.       Run the forward link and confirm it closes.

5.       Check off-axis EIRP density against the operator's limits.

6.       Round up to the next standard size, then confirm the dish fits the site.

How does frequency band choice change the dish diameter?

Band is the input that swings the answer most, because it sets both how much gain each metre of dish delivers and how much rain takes away.

Our view: when the earth station is a plant's primary WAN link, choose the band by climate first and throughput second. A Ka-band dish that runs fast for most of the year still fails the operations team on the stormy day they need it.

Why can't a smaller dish just use a more powerful amplifier?

The limit here is interference, not link performance. Beamwidth is roughly 70λ/D degrees. On a Ku-band uplink near 14 GHz, that gives a 1.2 m dish a beam of about 1.25°, while a 2.4 m dish narrows it to about 0.6°. Geostationary satellites sit only a few degrees apart, so a wide beam lights up neighbouring satellites too.

Think of a torch with a wide beam. Turn it up to light your target, and you also light your neighbour's window more brightly. An amplifier works the same way: it raises sidelobe energy in proportion to main-beam energy, so a small dish hits the operator's off-axis limit before it reaches the throughput you need. That is why the minimum diameter is often set by regulation rather than link physics, and why operators qualify specific antenna models.

The opposite limit matters too. A very large Ka-band dish has such a narrow beam that normal satellite drift can push it off target, which may mean adding tracking.

Where should the antenna sit on a hazardous process site?

A correctly sized dish is still useless if it cannot be installed safely with a clear view of the sky. Check these site factors before ordering:

·       Hazardous-area classification. Place the antenna and its outdoor RF electronics outside classified zones, or use equipment certified for the zone. Transmitted RF energy can also be an ignition source near flammable atmospheres, so have the site's hazardous-area engineer assess the beam path.

·       Blockage. Flare stacks, distillation columns, LNG tanks and construction cranes can cut across the look angle. Survey the full arc at the satellite's elevation, including planned structures.

·       Wind and foundation. Wind load rises steeply with dish area. Specify both operational and survival wind speeds against the local design code, especially on exposed coastal terminals.

·       Corrosion and cold. Salt spray and sulphur compounds call for suitable coatings. StarWin lists a de-icing system for its 4.5 m earth station antenna and a dehydrator that keeps the waveguide dry.

·       Cable run. A long run between the antenna and the equipment room adds loss. Fibre often makes more sense than coax.

How should the earth station design handle a link outage?

The final decision is how much plant risk the dish should carry on its own. Oversizing to buy the last fraction of availability is rarely the most efficient answer. Diversity usually works better:

·       Telemetry path. Carry low-rate SCADA and safety alarms over narrowband satellite IoT in rain-tolerant L/S band, or over a terrestrial network.

·       Broadband path. Carry bulk traffic on the Ku/Ka earth station.

·       Redundant RF chain. Use 1+1 BUC and LNB configurations to remove single points of failure.

·       Second orbit. Add a multi-orbit electronically steered phased array terminal as a diverse backup.

This layering applies StarWin's Multi-Band Convergence and Multi-Orbit Coordination strategy. One supplier can design it end to end: StarWin's narrowband satellite IoT terminals (TQZD-08, TQZD-10, TZ043), its Flat Panel Terminal Series including the Ka/Ku Full Dimensional ESA Terminal, and its Parabolic Antenna Series Earth Station Antennas. The satellite IoT terminals draw as little as 1 W and take field sensors over RS485 Modbus.

Frequently Asked Questions

What dish size does a typical LNG terminal need?
There is no typical size. It depends on traffic direction, band, the satellite's footprint, the rain climate and the operator's off-axis limits. Run the return-link budget first.

Is C-band or Ku-band better for a refinery?
In heavy tropical rain, C-band holds the link more reliably at the cost of a larger dish. In drier climates, Ku-band usually gives a smaller, more practical installation.

Can a flat-panel ESA terminal replace a fixed earth station?
It works well as a backup, a temporary link or a second-orbit path. For large primary apertures, a parabolic reflector remains the more practical choice.

Does the antenna itself need hazardous-area certification?
Only if it sits inside a classified zone. Most sites locate it in a non-classified area and confirm the RF beam path with their hazardous-area engineer.

How much rain margin should I add?
Calculate it from the site's coordinates, band and availability target using an established rain attenuation model. Avoid applying a generic figure.

Must the satellite operator approve the antenna?
Usually, yes. Operators qualify antenna models to control interference, so check the approved list before finalising the design.

About StarWin

StarWin is a Chengdu-headquartered provider of AI-driven compound solutions spanning Communication (5G and NTN across GEO, MEO and LEO), Navigation, Remote Sensing and Computing/Measurement. Its fixed earth-station antennas sit alongside electronically steered phased array terminals, flat-panel COTP and COTM terminals and narrowband satellite IoT terminals. Energy sites can therefore source the broadband primary link, the multi-orbit backup and the telemetry path as one integrated system. StarWin holds FCC, CE, RCM and ANATEL approvals and offers pre-sales and after-sales technical support plus remote and onsite training.

Planning an earth station for an LNG terminal or refinery? Talk to StarWin's engineering team about your link budget and site constraints at https://starwincom.com.