GHz to MHz for GNSS Carriers and Radar Letter Bands

Reading GNSS and Satellite Band Numbers in Megahertz

Band plans live in two dialects. Antenna catalogues, spectrum charts and regulatory allocations label everything above one gigahertz in GHz, while almanacs, receiver front-end specs and transponder plans stay stubbornly in MHz. An integrator comparing a patch antenna's passband against the carriers it has to receive spends half the afternoon shifting a decimal point three places to the right.

Conversion factor: one gigahertz holds 1 000 megahertz, so multiply the GHz figure by 1 000. The GPS L1 carrier at 1.575 42 GHz becomes 1.575 42 × 1 000 = 1 575.42 MHz, which is exactly how every almanac and receiver datasheet writes it.

Where the awkward decimals come from

Carriers Built From One Clock

Every GPS carrier is an integer multiple of a 10.23 MHz fundamental: 154 multiples give L1, 120 give L2 and 115 give L5. That integer relationship is why the gigahertz form never rounds neatly.

The Downlink Comes Home in MHz

A Ku-band dish receives 10.7–12.75 GHz, yet the coax behind it carries an IF of 950–2 150 MHz. The block downconverter subtracts a local oscillator, and everything after the mixer counts in megahertz.

Letters Instead of Numbers

Radar engineers say X-band rather than 8 000–12 000 MHz. The IEEE letters compress a whole span into one syllable, and expanding that syllable is the first step in choosing a filter, mixer or waveguide.

Stepping Through a Band Plan on This Page

Enter the carrier exactly as the band plan prints it

Type 1.57542 into the gigahertz field. Nothing is truncated on the way in, so a five-decimal navigation carrier survives the trip intact. Band tables written the European way work too: 1,57542 is read identically.

Read the megahertz figure while you type

The second field keeps pace keystroke by keystroke, so you can walk a whole constellation — L1, L2, L5, E5b, B3I — without pressing anything between entries. Digits are grouped with a space, which stops 1 602 being misread as 16 020.

Copy the bare number into a link budget

The copy button on either field hands over the digits alone, with no unit and no thousands spacing, which is what a spreadsheet cell or a path-loss formula expects. Pressing Ctrl+C inside a field does the same thing.

Go the other way for a receiver datasheet

When the number in front of you already arrives in megahertz — a 1 227.6 filter centre, say — press the swap arrows or simply type into the megahertz field. Both boxes are live, so direction follows whichever one you touch.

GNSS Carriers and IEEE Radar Letter Bands

The two tables below hold the numbers that come up most often on an antenna bench: the navigation carriers a modern receiver has to see, and the letter bands that decide which waveguide, filter and mixer you order.

Navigation signal	Carrier in GHz	Carrier in MHz	Constellations sharing it
L1 / E1 / B1C	1.575 42 GHz	1 575.42 MHz	GPS, Galileo, BeiDou
L2	1.227 6 GHz	1 227.6 MHz	GPS (P(Y) and L2C)
L5 / E5a / B2a	1.176 45 GHz	1 176.45 MHz	GPS, Galileo, BeiDou
E5b	1.207 14 GHz	1 207.14 MHz	Galileo
B3I	1.268 52 GHz	1 268.52 MHz	BeiDou
L1OF centre	1.602 GHz	1 602 MHz	GLONASS (FDMA channels)

Letter bands expanded back into megahertz

IEEE letter	Span in GHz	Span in MHz	What sits there
L	1–2 GHz	1 000–2 000 MHz	Navigation carriers, long-range surveillance
S	2–4 GHz	2 000–4 000 MHz	Weather radar, airport surveillance
C	4–8 GHz	4 000–8 000 MHz	Rain-tolerant satellite downlinks
X	8–12 GHz	8 000–12 000 MHz	Marine and imaging radar
Ku	12–18 GHz	12 000–18 000 MHz	Direct-to-home television downlinks
Ka	27–40 GHz	27 000–40 000 MHz	High-throughput satellite spot beams

Five Decimals Survive the Trip

Navigation carriers are quoted to the hundredth of a megahertz, and the output carries up to eight decimals, so 1.575 42 never collapses into 1.58 on the way across.

Round Trip Along a Receive Chain

The swap arrows flip the pair in place, which suits working down a downlink where the antenna is specified in gigahertz and the IF stage in megahertz.

Either Side Searches the Whole List

Both dropdowns are searchable, so a band edge you have just converted can be pushed further up or down the frequency scale without leaving the page.

Questions From the Antenna and Downlink Bench

Why is GPS L1 written as 1.575 42 GHz rather than a round 1.6 GHz?

Because the carrier is not chosen for tidiness, it is derived. Every GPS signal is an integer multiple of a single 10.23 MHz fundamental generated on board: 154 multiples give 1 575.42 MHz, 120 give 1 227.6 MHz and 115 give 1 176.45 MHz. Keeping the carriers coherent with the code chipping rate is what lets a receiver track carrier phase, so the awkward decimal is a deliberate consequence of the design. Convert to megahertz and the arithmetic reveals itself, since 1 575.42 divides cleanly by 10.23.

Which IEEE letter band does a given megahertz figure belong to?

Convert to gigahertz first and the letters fall out of the table above: 1–2 is L, 2–4 is S, 4–8 is C, 8–12 is X, 12–18 is Ku, 18–27 is K and 27–40 is Ka. A 9 410 MHz marine radar magnetron is therefore 9.41 GHz and squarely X-band. Two cautions are worth carrying: the IEEE radar letters are not the same as the satellite-industry letters, where a C-band uplink sits near 6 GHz, and plain K is usually skipped in practice because atmospheric water vapour absorbs heavily through its middle.

How does an LNB local oscillator turn a Ku-band downlink into an L-band IF?

By subtraction in a mixer. A universal Ku-band LNB carries two oscillators, 9.75 GHz for the low block and 10.6 GHz for the high block, selected by a 22 kHz tone sent up the coax. Take 10.7 GHz minus 9.75 GHz and you get 0.95 GHz, which is 950 MHz; the top of the low block at 11.7 GHz lands on 1 950 MHz. Switch to the 10.6 GHz oscillator and 11.7–12.75 GHz maps onto 1 100–2 150 MHz. That 950–2 150 MHz window is precisely what the cable and tuner were built for.

How far does Doppler move a navigation carrier?

Less than the satellite's orbital speed suggests, because only the line-of-sight component counts. For a medium-orbit spacecraft seen by a stationary receiver that rate peaks near 800 m/s, and 1 575.42 MHz × 800 ÷ 299 792 458 works out at roughly 4.2 kHz — call it a ±5 kHz search space, or about 3 parts per million of the carrier. An aircraft or a launch vehicle widens that window, which is why acquisition engines describe their search grid in kilohertz even though the carrier itself is written in megahertz.

Why is transponder bandwidth given in megahertz when the band is named in gigahertz?

Because the slice is thin compared with the band that contains it. A classic transponder is 36 MHz wide, with 54 MHz and 72 MHz variants in wider plans. Written in gigahertz those become 0.036, 0.054 and 0.072, numbers nobody wants to line up on a frequency plan. So the centre frequency stays in gigahertz while the occupied width stays in megahertz. Converting the centre is what lets you check that a 36 MHz slot really does fit between the two neighbours you were assigned.

Gigahertz to Megahertz