TABLE OF CONTENTS Radar development started in the 1930s and was shrouded in secrecy, especially as to which frequencies were used. This secrecy led to the use of the code letters for frequency bands in Britain and the United States as shown in Table C.1.
| British band letters [1] | United States band letters [2] | ||||||
|---|---|---|---|---|---|---|---|
| Frequency, GHz | Band | Frequency, GHz | Band | ||||
| 0.42 | - | 0.45 | P | ||||
| 1 | - | 2 | L | 1 | - | 2 | L |
| 2 | - | 4 | S | 2 | - | 4 | S |
| 4 | - | 8 | C | 4 | - | 8 | C |
| 8 | - | 12 | X | 8 | - | 12 | X |
| 12 | - | 18 | J | 12 | - | 18 | K u |
| 18 | - | 26 | K | 18 | - | 27 | K |
| 26 | - | 40 | Q | 27 | - | 40 | K a |
| 40 | - | 60 | V | 40 | - | 75 | V |
| 60 | - | 90 | O | 75 | - | 110 | w |
The former arbitrary letter systems have been superseded by those for electromagnetic surveillance, as shown in Table C.2.
| Band | Frequency range, GHz | ||
|---|---|---|---|
| A | 0 | - | 0.25 |
| B | 0.25 | - | 0.5 |
| C | 0.5 | - | 1.0 |
| D | 1.0 | - | 2.0 |
| E | 2.0 | - | 3.0 |
| F | 3.0 | - | 4.0 |
| G | 4.0 | - | 6.0 |
| H | 6.0 | - | 8.0 |
| I | 8.0 | - | 10.0 |
| J | 10.0 | - | 20.0 |
| K | 20.0 | - | 40.0 |
| L | 40.0 | - | 60.0 |
| M | 60.0 | - | 100.0 |
1. Sword, S. S., Technical History of the Beginnings of Radar, London: IEE Press, 1968.
