Electronics > RF, Microwave, Ham Radio

Question about portable scanners

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mehdi:
Hi
Why portable scanners (or wide-range receivers) support frequencies up to 3.0 GHZ?
What exists above 600MHZ which can be received with these receivers? (especially with a modulation such as AM/FM)
I was thinking that these are useful for receiving amateur/police/emergency radios (HF up to 500MHZ) and can't come up with an explanation for the wide coverage.

Jeroen3:
Lookup the frequency allocation table from your local telecom regulatory government body.
You'll see that there are lot of frequencies occupied. You'll find naval and aviation communications, beacons and navigation, satellite communication, military and other things that you wouldn't have imagined required RF space.
It most likely doesn't tell you anything about the details of the signal.

Lord of nothing:

--- Quote ---What exists above 600MHZ which can be received with these receivers? (especially with a modulation such as AM/FM)
--- End quote ---
In US the use the 800Mhz Band for Commercial Radios and 900Mhz Band is open for Radio Amateurs (what i remember).

Here in Austria quite nobody use Commercial Radio only for Mass Transportation have there Freq.
There are PMR446 Radios for 446 - 446.100

shawnb:
GHz receiving isn't usually practical for casual listening... it typically involves hunting for signals with tuned directional antennas, and the signals are often digitally modulated.  But some people enjoy experimenting and trying to decode the digital, or just tracking satellites by receiving the signals or CW beacons.

As Jeroen3 said, you can get a general sense for what is up there by looking at a frequency allocation table from your country (or the ITU).  You may also be able to find a list of specific frequencies used in your area, since most likely anything you hear on UHF (300 Mhz+) is going to either be a local station or a satellite.

The top end of the UHF band is 3 GHz, so a typical wide-band receiver IC is probably designed to operate up to there.  If the circuit supports it, there isn't really a reason for a receiver manufacturer to artificially limit the coverage of the receiver.  In other words, they aren't adding additional circuitry to receive GHz because there is useful demand for it, it just so happens that the chips used already support it.

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