Space communication involves sending signal emitted from the antenna of the transmitter to the antenna of the receiver. Describe in brief, mentioning frequency range of operation, four different ways by which space communication becomes possible?
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Please find below the solution to the asked query:
A band is a small section of the spectrum of radio communication frequencies, in which channels are usually used or set aside for the same purpose.
Above 300 GHz, the absorption of electromagnetic radiation by Earth's atmosphere is so great that the atmosphere is effectively opaque, until it becomes transparent again in the near-infrared and optical window frequency ranges.
To prevent interference and allow for efficient use of the radio spectrum, similar services are allocated in bands. For example, broadcasting, mobile radio, or navigation devices, will be allocated in non-overlapping ranges of frequencies.
Each of these bands has a basic band plan which dictates how it is to be used and shared, to avoid interference and to set protocol for the compatibility of transmitters and receivers.
As a matter of convention, bands are divided at wavelengths of 10n metres, or frequencies of 3×10n hertz. For example, 30 MHz or 10 m divides shortwave (lower and longer) from VHF (shorter and higher). These are the parts of the radio spectrum, and not its frequency allocation.
| Band name | Abbreviation | ITU band | Frequency and wavelength in air | Example uses |
|---|---|---|---|---|
| Extremely low frequency | ELF | 1 | 3–30 Hz 100,000 km – 10,000 km | Communication with submarines |
| Super low frequency | SLF | 2 | 30–300 Hz 10,000 km – 1000 km | Communication with submarines |
| Ultra low frequency | ULF | 3 | 300–3000 Hz 1000 km – 100 km | Submarine communication, communication within mines |
| Very low frequency | VLF | 4 | 3–30 kHz 100 km – 10 km | Navigation, time signals, submarine communication, wireless heart rate monitors, geophysics |
| Low frequency | LF | 5 | 30–300 kHz 10 km – 1 km | Navigation, clock time signals, AM longwave broadcasting (Europe and parts of Asia), RFID, amateur radio |
| Medium frequency | MF | 6 | 300–3000 kHz 1 km – 100 m | AM (medium-wave) broadcasts, amateur radio, avalanche beacons |
| High frequency | HF | 7 | 3–30 MHz 100 m – 10 m | Shortwave broadcasts, citizens' band radio, amateur radio and over-the-horizon aviation communications, RFID, over-the-horizon radar, automatic link establishment (ALE) / near-vertical incidence skywave (NVIS) radio communications, marine and mobile radio telephony |
| Very high frequency | VHF | 8 | 30–300 MHz 10 m – 1 m | FM, television broadcasts and line-of-sight ground-to-aircraft and aircraft-to-aircraft communications, land mobile and maritime mobile communications, amateur radio, weather radio |
| Ultra high frequency | UHF | 9 | 300–3000 MHz 1 m – 100 mm | Television broadcasts, microwave oven, microwave devices/communications, radio astronomy, mobile phones, wireless LAN, Bluetooth, ZigBee, GPS and two-way radios such as land mobile, FRS and GMRS radios, amateur radio |
| Super high frequency | SHF | 10 | 3–30 GHz 100 mm – 10 mm | Radio astronomy, microwave devices/communications, wireless LAN, most modern radars,communications satellites, cable and satellite television broadcasting, DBS, amateur radio |
| Extremely high frequency | EHF | 11 | 30–300 GHz 10 mm – 1 mm | Radio astronomy, high-frequency microwave radio relay, microwave remote sensing, amateur radio,directed-energy weapon, millimeter wave scanner |
| Terahertz orTremendously high frequency | THz or THF | 12 | 300–3000 GHz 1 mm – 100 μm | Terahertz imaging – a potential replacement for X-rays in some medical applications, ultrafast molecular dynamics, condensed-matter physics, terahertz time-domain spectroscopy, terahertz computing/communications, sub-mm remote sensing, amateur radio |
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