Newly-minted
operators often ask what bands they should get on, and whether it's
worth getting equipment for certain bands. Here is a very subjective
and very biased view of the various ham radio bands available to US
hams:
* 160M
- 160M
is called "top band" since it is traditionally the longest of the
original bands allocated to ham radio. DX propagation is very difficult
due to D-layer absorption; propagation behaviour is much like that of
AM mediumwave broadcast. It is very, very subject to atmospheric noise
and tends to attract very dedicated people with large backyards. There
is a 160M SSB QRP frequency at 1.910 Mhz for people who want a
double-handicap. 160M can propagate somewhat through a groundwave which
hugs the ground and this can give local communication beyond the point
of line of sight.
* 80M
- This
band still have substantial signal absorption during daytime making it
only usable for DX at night. However, 80M seems to be the preferred
band for medium-distance nighttime communication, often with NVIS
antennae. The CW portion of 80M is active nearly worldwide. The phone
portion (often referred to as 75M) is not shared by most
non-US-and-Canada countries, and is very crowded with ragchewers who
tend to sit on one frequency forever. Much of the stereotype of grouchy
and profane old ham radio operators comes from 75M phone, but the CW
section is far more polite. There is some groundwave propagation on
this band.
* 60M
- This
is the newest of the ham bands, established in 2003. Unlike all the
other ham bands, it is channelized with only five individual 2.8 Khz
wide channels. Because it is so new, many radios designed for ham band
use do not support it, and few non-US countries use it. It attracts
people who are looking for some place quiet and different. Another
oddity about this band is that the maximum power allowed is specified in
terms of field strength and not in terms of output power to the
antenna, therefore high gain antennas buy you no improvement for
transmission.
* 40M
- This
is one of the most active of the traditional ham bands. It has good
propagation characteristics for nighttime DX even at the bottom of the
solar cycle, and medium-distance propagation even during the daytime.
Unfortunately it is shared with high powered shortwave broadcasters and
sometimes finding a place between all the broadcast carriers can be
difficult. 40M collects an interesting mix of ragchewers and DXers.
The European 40M phone band is arranged so that it overlaps with much of
the Extra phone segment and only a little bit of the General phone
segment. If you want to do phone DX on 40M, get an Extra license.
* 30M
- This
is a tiny little slice of bandwidth assigned in 1979 by the World
Administrative Radio Conference (and therefore not acceptable for QSOs
in many contests). Because there is so little of it and because it is
shared with other services, it is CW only. The propagation
characteristics are much like those of 40M with good DX even at the
bottom of the solar cycle.
* 20M
- As
we raise up in frequency, there is less and less daytime absorption, to
the point where 20M is a very useful band during the daytime. This is
probably the most popular band for DX, although band openings appear
less frequently than they do on 40M especially during lower parts of the
solar cycle. If you have a 60M dipole, it will also resonate well on
20M.
* 17M
- Another
one of the WARC bands (and therefore ineligible for many contests), 17M
has similar propagation characteristics to 20M although even more
sensitive to solar activity.
* 15M
- As
we raise even farther in frequency, band openings on 15M are less and
less frequent and require a higher level of solar activity.
Occasionally there is daytime sporadic-E propagation on this band as
well. One of the cool things about 15M is that a dipole tuned for 40M
will just about cover 15M as well.
* 12M
- This
is one of the newest of the WARC bands. Out of bounds for contesting.
Mostly usable only during solar maxima. Propagation seems to be much
like 10M.
* 10M
- This
band is usable for DX only during solar maxima, really, but sometimes
there are short openings due to sporadic-E propagation. 10M openings
seem to happen mostly during the daytime. There is a small allocation
for 10M FM which is intended for short distance communication but can
occasionally be a DX surprise. Much of the problem with 10M has to do
with its proximity to the 11M citizens radio band. This has resulted in
a lot of "freebanders" using illegally-modified CB gear in the bottom
of the band, and it has resulted in laws prohibiting the sales of
high-powered amplifiers capable of 10M use. The other side of this
coin, though, is that cheap CB gear can often be modified for legal use
by hams on 10M.
* 6M
- This
is the "magic band" that lies between HF and VHF. Although there are a
few 6M repeaters in the country and people will sometimes come back to
you if you call on 52.525 with an FM transmitter, what makes 6M cool is
that occasionally there is DX propagation. During the solar maximum,
conventional skip is possible but at other times there is occasional
sporadic-E and tropospheric ducting. The majority of 6M DXers use SSB,
but even an old Army field radio tuned to the FM calling frequency can
bag interesting QSOs. Because you never know what 6M will do, there is
an active set of beacons on the band that you can leave a receiver tuned
to so as to alert you to band openings.
* 2M
- This
has become the de-facto local communications band. There are very few
parts of the country out of range of a 2M repeater. While tropospheric
ducting can allow 2M DX and sporadic-E propagation has been seen on this
band, these are more the realm of a small group of dedicated obsessives
than regular propagation modes for daily use. 2M is very popular both
for direct simplex communication and for repeater use. However, you
should know that the repeater culture varies greatly from place to
place; listen to the repeater for a while before jumping in. 2M
propagation is almost entirely line of sight.
* 1.25m (220)
- 220
is another VHF band with line of sight propagation. It is a strange
band without a lot of activity, and because of that in the late 1980s,
United Parcel Service petitioned the FCC for the 220-222 Mhz section of
the band which was granted to them. Although UPS never used it, it was
never returned to amateur use, so hams currently have the 220-225 MHz
sections, and in addition an odd chunk at 219-220 Mhz which is allocated
only for "fixed point to point digital messaging services," ie. packet
radio. Some repeaters exist on 220 but it is very much an underutilized
band.
* 70cm (440)
- This
UHF band can give better propagation in urban areas than 2M, because of
reduced problems with multipath (where multiple reflections from the
same source appear at the receiver at different times). Because of
congestion on the 2M band (especially on repeaters) there have been many
people moving to 440.
* 33 cm (902)
- Much
of this band is shared with ISM devices, so you may encounter baby
monitors and security cameras appearing alongside ham users. Some
repeaters on this band exist. Propagation characteristics are much more
touchy than on 2M and 440, with sometimes a six-inch shift in position
enough to change reception characteristics due to multipath.
* 13 cm (2300-2310 and 2390-2450)
Yes, if you noticed, this band overlaps with the ISM band used for WiFi
and many other things. This means that you can use existing WiFi
hardware and the like in this band. But it's not quite that simple.
If you use 2.4 GHz as an ism band you can use encryption and arbitrary
ID and ISM-band power limits. BUT, if you want to use higher power as
allowed for ham use, you have to use your callsign and no encryption.
It's the same frequency but under a different allocation paragraph in
the regs. However, hams have done line of sight between mountaintops
using off the shelf WiFi
hardware and high gain antennas, for hops longer than 30 miles, so do not despair that the band is not useful.
* The Other Microwave Bands
- I
don't know anything about the higher microwave bands, but there are a
lot of them, from 3300 Mhz on up to an authorized allocation at 241-250
GHz. Some of these bands have frequencies shared with ISM users, some
of them are on frequencies with substantial attenuation in air. Please
add something useful to this.
http://www.arrl.org/graphical-frequency-allocations