Satellite Footprint & EIRP Explained: Pick the Right Dish Size

📡 KNOWLEDGE GUIDE

Satellite Footprint & EIRP Explained 2026: Pick the Right Dish Size

Updated: November 10, 2026 (8:00 PM PKT) — 1BissKey's practical evergreen guide to satellite footprints and EIRP: what a footprint map is, what the dBW numbers on it mean, how a 3 dB drop doubles the dish you need, and how to pick the right dish size for your location — with a worked example and a Paksat 1R look at Pakistan.

Two houses on the same street, two dishes pointed at the same satellite — one gets a perfect picture with a 60 cm dish, the other needs a 120 cm dish for the same channel. And a friend in another city cannot get that channel at all, no matter how big his dish is. The reason is not the receiver, the LNB or the cable. It is the satellite's footprint — the patch of Earth its signal actually covers — and the strength of that signal where you live, measured as EIRP.

This guide explains both ideas in plain English. You will learn what a footprint map is, how to read its contour lines, what the dBW numbers mean, why a 3 dB drop in signal means a dish with twice the area, and how to use a published dish-size chart to choose the right dish before you buy. There is a worked example, a look at Paksat 1R over Pakistan, and troubleshooting for life at the edge of a footprint. No engineering degree needed — just the map your satellite already publishes.

⚡ Quick answer: A footprint is the area on Earth a satellite beam covers; EIRP in dBW is how strong the signal is at each point on that map. The closer you are to the beam centre, the stronger the signal and the smaller the dish you need. A 3 dB drop in EIRP means you need a dish with twice the area. Check the footprint map on LyngSat before buying a dish — the map, not the shop, decides the size.

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Contents

• What is a satellite footprint?
• What is EIRP?
• How to read a footprint map
• The 3 dB rule: why a small power drop means a much bigger dish
• EIRP to dish size: the chart
• Worked example: two cities, one satellite
• Beam types: wide, regional and spot
• Paksat 1R and Pakistan: why small dishes work here
• Ku-band vs C-band: different rules for dish size
• Step by step: pick the right dish size for your location
• Troubleshooting: weak signal at the footprint edge
• Safety
• Frequently asked questions

What Is a Satellite Footprint?

A footprint is the area on the surface of the Earth covered by the microwave signal from a satellite transponder. A geostationary satellite sits about 36,000 km above the equator, and its antenna shapes the downlink into a beam that lands on a particular region — a continent, a group of countries, or a single country. The footprint is simply the outline of where that beam lands. If you are inside it, the signal reaches you; if you are outside it, it does not — or only a faint spillover does.

Think of it like a torch beam on a wall: the satellite is the torch, the beam is the light, and the footprint is the lit patch. Move the torch, and the lit patch moves. Aim the beam tighter, and the patch gets smaller and brighter. That is exactly how satellites work — and it is why the same satellite can be easy to receive in one country and impossible in another.

One more thing to fix in your mind early: a footprint belongs to a beam, not to a whole satellite. A modern satellite carries several beams, each aimed at a different place and each with its own footprint. So the correct question is never "what is this satellite's footprint?" but "what is the footprint of the beam carrying the channel I want?" — because two channels on the same satellite can sit on two different beams with two very different footprints.

What Is EIRP?

EIRP stands for Effective Isotropically Radiated Power. It is the apparent power the satellite radiates toward the receiver, as if the signal were radiated equally in all directions from a point source. In practice it is the satellite transmitter's power multiplied by the gain of its transmit antenna — a focused antenna makes the same transmitter power count for far more in the direction it points.

EIRP is written in dBW — decibels relative to one watt. The dB scale is logarithmic, so small changes in the number mean large changes in power. A few reference points make it concrete:

• 45 dBW is the same as about 31,600 watts radiated toward that spot (10 raised to 45/10).
• 52 dBW is about 158,000 watts — the same satellite, aimed tighter, can look five times more powerful on the ground.
• Every 3 dB more means double the power; every 3 dB less means half the power.

Why does this matter to you? Because your dish has to collect enough of that power to lock the signal. A stronger EIRP at your location means your dish can be smaller; a weaker EIRP means it must be bigger. The footprint map is how you find out which one applies to you.

How to Read a Footprint Map

Footprint maps are drawn like weather maps: a map of the region with contour lines drawn across it, each line labelled with an EIRP value in dBW — 52 dBW, 49 dBW, 46 dBW, 43 dBW and so on, falling as you move away from the centre. The diagram below shows the pattern:

Reading one takes three steps:

1. Find your location on the map. Note which contour lines you sit between. If you are between the 49 dBW and 46 dBW lines, your EIRP is somewhere in that range — use the lower (weaker) number when sizing your dish, so you have margin.
2. Check you have the right beam. Footprint pages list beams by name — for example "Asia Main", "Europe" or a regional beam. Different beams from the same satellite cover different countries, so confirm the beam that carries your channel. LyngSat lists the beam next to each transponder.
3. Read the number, not the colour. Some maps colour the contours instead of labelling them, and the colours vary from map to map. Always find the dBW figure in the legend — a bright colour on one map can mean a weak signal on another.

Two cautions. First, published footprints are not always exact — they are predictions, and real signal can bleed a little beyond the drawn edge, especially with a large dish. Second, coverage is not even inside the footprint: two towns on the same contour line can still differ, and satellites low on your horizon (far from due south for Pakistan) arrive weaker than the map suggests. Treat the map as a guide, then confirm with your receiver's signal-quality meter.

The 3 dB Rule: Why a Small Power Drop Means a Much Bigger Dish

The single most useful rule in dish sizing is the 3 dB rule: a 3 dB drop in EIRP means you need a dish with twice the area to collect the same amount of signal. A 6 dB drop needs four times the area. This is physics, not opinion — your dish collects signal in proportion to its area, so when the signal gets weaker you must collect over a bigger patch of sky.

Area and diameter are easy to confuse, and the difference matters when you shop. Doubling the area does not mean doubling the diameter — area grows with the square of the diameter. A dish with twice the area is only about 1.4 times wider (the square root of 2). And a dish with four times the area is twice the diameter. So:

EIRP change	Power change	Dish area needed	Dish diameter needed
3 dB less	Half the power	2x the area	~1.4x wider
6 dB less	Quarter the power	4x the area	2x wider
9 dB less	One-eighth the power	8x the area	~2.8x wider
3 dB more	Double the power	Half the area	~0.7x the width

This is why a channel that is easy in Lahore can be hard in Quetta, and why moving a few hundred kilometres can force a dish upgrade: every 3 dB you lose at the edge of a beam pushes you to the next dish size up. It is also why "just buy a bigger dish" works — but only up to a point. Doubling the dish diameter gives you four times the area, worth about 6 dB of extra signal. If you are 10 dB outside the footprint, no practical home dish will save you.

EIRP to Dish Size: The Chart

The table below is the published Ku-band dish-size chart (assumes a Universal LNB with a 0.7 dB noise figure). Find your EIRP on the footprint map, read across, and you have the minimum dish diameter for reliable reception. Different calculators disagree slightly — for example, the SatLex EIRP calculator says 28 cm is enough at 51 dBW, while this chart says 55 cm — because they assume different rain margins and LNB figures. Use the chart as a guide and go one size up if you want rain-proof reception.

EIRP at your location	Minimum dish diameter (Ku-band)	Typical use
60 dBW	30 cm	Very strong beam centre
55 dBW	40 cm	Strong beam centre
52 dBW	50 cm	Strong signal, small dish
50 dBW	60 cm	Standard small dish
48 dBW	60 cm	Standard small dish
46 dBW	80 cm	Medium dish
45 dBW	90 cm	Medium dish
43 dBW	100 cm	Large home dish
42 dBW	110 cm	Large home dish
40 dBW	120 cm	Large dish, weak signal
38 dBW	150 cm	Very weak signal
36 dBW	240 cm	Fringe reception, specialist dish
33 dBW	400 cm	Fringe, commercial-size dish

Notice how fast the sizes grow at the weak end: from 48 dBW to 36 dBW is a 12 dB drop, and the dish grows from 60 cm to 240 cm — four times the diameter, sixteen times the area. That is the 3 dB rule compounding. The practical lesson is to check the map before buying: a 60 cm dish is cheap and easy to mount, a 240 cm dish is a different project entirely.

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Worked Example: Two Cities, One Satellite

Take one satellite with a beam centred on City A and fading toward City B. On the footprint map, City A sits on the 48 dBW contour and City B sits on the 45 dBW contour — a 3 dB difference. Work out what each city needs, using the chart above:

1. City A (48 dBW): the chart says a 60 cm dish is the minimum.
2. City B (45 dBW): the chart says a 90 cm dish is the minimum.
3. Check the 3 dB rule: a 60 cm dish has an area of about 2,827 cm² (π × 30²). A 90 cm dish has an area of about 6,362 cm² (π × 45²). That is about 2.25 times the area — very close to the doubling the 3 dB rule predicts. The small difference is the chart rounding to dish sizes you can actually buy.
4. Add rain margin: in City B, a 90 cm dish locks the signal in clear weather but may break up in heavy rain. Going one size up — a 100 cm or 110 cm dish — buys the margin that keeps the picture stable. The rule from installers is simple: if the picture is only just OK in clear weather, go bigger.

Now you see why the same channel, same satellite, same LNB and same receiver can need a 60 cm dish in one city and a 90 cm dish in another — and why asking "what size dish do I need for this satellite?" without saying where has no answer.

Beam Types: Wide, Regional and Spot

Not all beams are shaped the same. Satellites use three kinds of beam, and the type decides both the size of the footprint and the strength of the signal inside it:

Beam type	Coverage	Signal strength	Dish needed
Wide / global beam	A continent or more	Weakest — power spread thin	Largest
Regional beam	A region or group of countries	Medium	Medium
Spot beam	One country or a small area	Strongest — power concentrated	Smallest

The trade-off is fixed: the same transmitter power can cover a big area weakly or a small area strongly, never both. That is why a pay-TV spot beam over one country can be received on a 45 cm dish while a wide beam from the same satellite needs 120 cm or more. It is also why a channel can vanish when a broadcaster moves it from a spot beam to a regional beam — the footprint changes, and your dish may suddenly be too small. When a channel disappears overnight and your dish has not moved, check whether its beam changed before you climb onto the roof.

Paksat 1R and Pakistan: Why Small Dishes Work Here

Paksat 1R sits at 38.0°E in geostationary orbit. It was launched on 11 August 2011 on a DFH-4 bus, is operated by SUPARCO, and carries 30 transponders — 18 in Ku-band and 12 in C-band — with a 15-year design life. Its beams are aimed at South Asia, which puts Pakistan near the centre of the beam rather than at its edge. That is the whole reason a small dish works for Paksat 1R in Pakistan: we are sitting where the signal is strongest.

Practically, that means most Paksat 1R Ku-band channels lock comfortably on the standard 60–90 cm dishes sold in Pakistani markets, and C-band channels need the larger 6–8 ft dishes that C-band always needs — not because the satellite is weak, but because C-band works at a lower frequency and needs more collecting area for the same result. Two things to check before you blame the dish:

• Check the beam on LyngSat. Paksat 1R's LyngSat page lists the beam next to every transponder, with EIRP values given for Islamabad. If the transponder you want sits on a beam centred elsewhere, your EIRP will be lower than the headline figure.
• Check the list is current. Transponders move and go off air. Verify the frequency on LyngSat or KingOfSat — or on this blog's own Paksat-1R channel list with frequency — before you re-aim anything. Our dish site survey guide covers checking the line of sight for a Paksat 1R installation.

A note on numbers: this guide does not print a single Paksat-1R EIRP figure, because the value depends on the beam and the transponder — LyngSat lists them per beam, and that is the number to use. Any article that gives you one number for a whole satellite is oversimplifying.

Ku-Band vs C-Band: Different Rules for Dish Size

The same EIRP does not mean the same dish in both bands. Ku-band (around 11–12 GHz) and C-band (around 4 GHz) behave differently, and the chart in this guide is a Ku-band chart:

• Ku-band: higher frequency means more antenna gain per centimetre of dish, so Ku-band works on small dishes — 60–90 cm in most of Pakistan. The price is rain: Ku-band signals fade in heavy rain, so the rain margin matters more.
• C-band: lower frequency means less gain per centimetre, so C-band needs a much bigger dish for the same signal — typically 6–8 ft (180–240 cm) for home reception. The reward is toughness: C-band barely notices rain that would kill a Ku-band picture.
• Never apply a Ku-band chart to C-band. A C-band transponder at 45 dBW does not work on a 90 cm dish. Use a C-band chart, or ask an installer who works with C-band in your area.

This is also why Paksat 1R needs two dish sizes in the same house: its 18 Ku-band transponders work on a small dish, while its 12 C-band transponders need a big one. If you only watch Ku-band channels, the small dish is enough — the C-band dish is a separate project. Our signal strength vs quality guide explains how to tell whether a weak picture is a dish-size problem or something else entirely.

Step by Step: Pick the Right Dish Size for Your Location

1. List the channels you want, then find their satellite and beam. Check the channel on LyngSat — note the satellite position (for example 38.0°E for Paksat 1R) and the beam name next to the transponder.
2. Open the footprint map for that beam. On LyngSat, the satellite page links to footprint maps. Find your town on the map and read the EIRP contour you sit on — or between. Use the weaker number if you sit between two lines.
3. Read the dish size off the chart. Use the table in this guide for Ku-band. If your EIRP is 48 dBW, the chart says 60 cm; if it is 42 dBW, it says 110 cm.
4. Go one size up for rain margin. If the chart says 60 cm, buy 75–90 cm. The extra size costs little and keeps the picture stable in the monsoon. This is the single best money you will spend on a satellite installation.
5. Check the LNB matches the chart's assumption. The chart assumes a Universal LNB with a 0.7 dB noise figure. A poor-quality LNB with a high noise figure eats into your margin — a good LNB is cheaper than a bigger dish. Our replace a faulty LNB guide covers choosing one.
6. Confirm with the signal-quality meter. After aiming, check the receiver's signal quality (not just strength) in clear weather. If quality is below about 70% on a DVB-S2 transponder, your margin is thin — consider the next dish size up before the rain arrives.
7. Re-check if a channel moves beam. If a channel disappears overnight, check LyngSat again — a beam change can move your EIRP by several dB, and no re-aiming will fix a dish that is now too small.

Troubleshooting: Weak Signal at the Footprint Edge

Symptom	Likely cause	What to do
Some channels fine, others break up	Weak channels sit on a different, weaker beam	Check the beam and EIRP for the weak transponder on LyngSat; the dish may be sized for the strong beam only
Picture fine in sun, breaks in rain	No rain margin — dish is the minimum size for clear weather	Go one or two sizes up; check the LNB skew, which costs signal when it is off — see our LNB skew guide
Neighbour gets a channel, you cannot	Different dish size, different LNB, or a tree or building in your line of sight	Compare dish sizes first; then run a dish site survey for obstructions
Signal strength high, quality zero	Wrong beam, wrong polarization, or wrong transponder values — not a dish-size problem	Re-check frequency, polarization, symbol rate and FEC against a current list; use a satellite finder to confirm you are on the right satellite
Channel worked for years, now gone	Broadcaster moved the channel to another beam or transponder	Look the channel up on LyngSat or KingOfSat and check the new beam and EIRP before buying anything

Safety

Dish sizing is safe desk work — the risky part is what comes after, when a bigger dish goes up. A 120 cm or larger dish catches far more wind than a 60 cm one, so the mount, pole and wall fixings must be rated for it: a dish that rips off a wall in a storm can injure someone below. Always use the mount the manufacturer supplies for that dish size, bolt into solid brick or concrete (never into hollow blocks or plaster alone), and ground the dish and coax properly against lightning. Work on roofs only with a second person present, a secure ladder, and dry conditions — never in rain or high wind, and never near overhead power lines. If the installation needs work above a single storey, hire a professional installer; the cost of the job is far less than the cost of a fall.

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Frequently Asked Questions

What does dBW mean?

dBW is power measured in decibels relative to one watt. 0 dBW is 1 watt, 10 dBW is 10 watts, 20 dBW is 100 watts, and 45 dBW is about 31,600 watts. Because the scale is logarithmic, every 3 dB doubles or halves the power. On a footprint map, dBW tells you how much signal power the satellite delivers to that spot on Earth.

What EIRP do I need for a 60 cm dish?

On the Ku-band chart, a 60 cm dish is the minimum at about 48–50 dBW. If your location's EIRP is lower than that, a 60 cm dish will struggle — especially in rain. Check your EIRP on the footprint map first; if it is 45 dBW, you need about 90 cm instead.

Can I receive a satellite outside its footprint?

Sometimes, just outside the edge, with a much larger dish than the chart suggests — published footprints are predictions and real signal bleeds a little beyond the drawn lines. But the further outside you are, the faster the signal falls, and a few dB outside the edge can mean a dish several times larger. If you are well outside the footprint, no practical home dish will work.

Why does my neighbour get a channel I cannot?

Usually one of three reasons: their dish is bigger, their LNB is better (lower noise figure), or their line of sight is clear while yours is partly blocked. Less often, you are on different beams without knowing it — check the transponder and beam on LyngSat before comparing dishes.

Does a bigger dish always help?

Almost always, up to a point: doubling the diameter gives four times the area, worth about 6 dB of extra signal. But a bigger dish is also harder to aim precisely, catches more wind, and costs more to mount safely. It cannot fix a wrong frequency, wrong polarization, a dead LNB, or a channel that has moved to a different beam. Fix the settings first, then size the dish.

Where do I find footprint maps?

LyngSat publishes footprint maps for most satellites — open the satellite's page and follow the footprint or beam links. SatLex offers a free EIRP calculator that turns an EIRP value into a recommended dish size. Satellite operators also publish footprint maps in their technical documentation. Always use the map for the exact beam carrying your channel.

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📚 Related Posts

• Paksat-1R Complete Channel List with Frequency
• Dish Site Survey Guide 2026: Pick the Perfect Spot Before You Mount
• Signal Strength vs Quality Explained: What Your Receiver Meter Really Means
• LNB Skew & Polarization Guide 2026: Set It Right, Get Every Channel
• How to Replace a Faulty LNB: Step-by-Step Guide 2026
• Satellite Finder Guide 2026: Aim Your Dish Like a Professional
• Align Your Dish with a Phone: Compass & Inclinometer Guide 2026
• 1BissKey New Look October 2026: Receiver Software Updates & Guide

Sources

1. Satellite TV Europe — Dish Size Chart (EIRP to dish diameter, Ku-band, 0.7 dB LNB)
2. SatSig — Explanation of Satellite Beam Coverage Patterns (contour lines, 3 dB / 6 dB rule, 45 dBW = 31,622 W)
3. SatLex — EIRP Reception Calculator (51 dBW = 28 cm, 44 dBW = 60 cm)
4. Satellites.co.uk — Glossary: Sats and Dish Sizes (per-beam sizing, footprint edges)
5. TechSawa — Satellite Beams and the Corresponding Dish Size
6. LyngSat — Satellite footprint maps and transponder lists
7. Wikipedia — PAKSAT-1R (38.0°E, launched 11 August 2011, 30 transponders: 18 Ku + 12 C)
8. 1BissKey — Paksat-1R Complete Channel List with Frequency

Disclaimer: EIRP values and dish sizes in this guide are indicative, based on published charts and calculators — actual reception depends on your exact location, LNB quality, cable losses and local obstructions. Always confirm a transponder on LyngSat or KingOfSat before tuning, and follow local safety rules when working on roofs. 1BissKey publishes guides for education; always follow your receiver manufacturer's instructions.