Amateur radio is a tool for long-distance communication. Pieces of the electromagnetic spectrum are allocated for amateur radio use. Rather than clumping all of these pieces together, they are spread out across many frequencies so that amateur radio operators can experiment with different electronics, radio technologies and antennas, further expanding humankind’s understanding of the world.

In terms of radio frequencies, the spectrum is divided into categories. In amateur radio, high frequency (HF) encompasses frequencies below 30 MHz, very high frequency (VHF) is from 30 MHz to 300 MHz, and 300 MHz to 3 GHz are ultra high frequencies (UHF). This article will discuss how and when to use each of the HF allocations.

Besides specifying operating spaces by frequency, amateur radio operators also use approximate wavelength to name the band. For example, the 14.000 MHz to 14.350 MHz band is also referred to as the “20 meter” band. This follows the formula:

Where the wavelength is in meters, frequency is in Hertz, and the speed of light is approximately 3.0 × 10⁸ m/s.

Most bands allow multiple data transmission modes. Morse code (also called Continuous Wave, or CW), Frequency Modulation (FM), Amplitude Modulation (AM), Single Sideband (SSB) and an ever-changing set of digital modes are all allowed, with a few notable exceptions. When using SSB, frequencies greater than 14.350 MHz use Upper Sideband (USB), and frequencies lower than 14.350 MHz use Lower Sideband (LSB), by convention. The higher frequencies of each band are used for voice modes, and the lower parts of the band are for Morse code and digital modes. Most bands also allow up to 1,500 W output power, though there are several exceptions to this rule as well.

The HF bands

These HF bands each have a different use. While amateur radio contacts can occur anywhere on Earth, on any band, during any time of day, any season and at any point during the solar cycle, certain conditions favor one band over the other.

Radio signals bounce off the ionosphere. The frequency and the distance between two points are part of the equation as to whether or not communication is possible. The rest is up to the ionosphere and how solar emissions, time of day, noise and other factors determine how “reflective” the ionosphere can be in a given circumstance. Think of it like going fishing — a radio operator transmits a signal, sometimes hearing no response, and sometimes hearing a station.

10 meters

The 10 meter band is a great starter band for newly licensed amateur radio operators. Available with the lowest class of amateur radio license (Technician class), and requiring the smallest antennas of all HF bands, it is easy to jump in and start using 10 meters.

Ten meters also has the widest allocation of all of the HF bands, covering from 28.000 MHz to 29.700 MHz. Amateur radio operators can output up to 1,500 W on this band, but when conditions are right, low power operation will work perfectly.

Perhaps the neatest feature of the 10 meter band is the distance at which communications occur. It might be difficult to talk to a person in the next county, but talking to another country is relatively easy. When the author lived in Virginia, he never made contact with Maryland, but worked over 100 countries in Europe, Africa, Asia, South America and the Caribbean, with only 25 W output power.

Typically, 10 meters is open for communication during the day, becoming difficult at night. Furthermore, it is the band most heavily influenced by the 11-year solar cycle. When the solar cycle is at its peak with more sunspots, 10 meters is also at its peak usefulness.

Overall, 10 meters is great for long distance communication during the daytime when there are sunspots.

12 Meters

The 12 meter band is just a narrow slice of the electromagnetic spectrum, covering 24.890 MHz to 24.990 MHz. In a lot of ways, 12 meters is similar to 10 meters. It is slightly less sensitive to the solar cycle and is open a little later in the evening than 10 meters, but otherwise has similar propagational properties. The big difference between 10 meters and 12 meters is that there are no amateur radio contests on 12 meters.

“QSL” cards that confirm contacts from Japan, Croatia and the Azores. Source: Seth Price

15 Meters

The 15 meter band is a little less sensitive to the solar cycle and diurnal cycles, but it is still considered a daytime band. It occupies 21.000 MHz to 21.450 MHz. It is still good for talking long distances, and because it is open more often, it is a good place to learn radio operating skills most of the time. Radio operators can come home from work and jump right onto 15 meters, even a little bit after the sun has set in the evening, and even at the lower parts of the solar cycle.

17 meters

Another narrow slice, the 17 meter band runs from 18.068 MHz to 18.168 MHz. It has some parallels to the 12 meter band, in that there is no contesting on this band.

Perhaps the most common use for 17 meters is when there is a large radio contest in progress. Common bands, such as 15 meters, 20 meters and 40 meters, may be crowded with lots of stations. For those operators not interested in the contest, they can hop on 17 meters and have conversations or search for long distance stations without the noise and the chaos of a radio contest.

In terms of propagation, if 20 meters is open, likely 17 meters is open as well. Guaranteed if 15 meters and 20 meters are both open, 17 meters will be open.

20 meters

This is perhaps the most general purpose band of them all. The 20 meter band runs from 14.000 MHz to 14.350 MHz and is open regardless of the time in the solar cycle. Being an all-purpose band, it is one for conversations, contesting and some long-distance communication. Under certain conditions, it can be quite crowded on this band.

In terms of distance of communication, it is perhaps the easiest band to “Work All States,” as signals from this band tend to bounce off the atmosphere at different levels throughout the day. It can still be challenging to get the “home” state as well as the bordering states, but not nearly as challenging as with other bands.

30 meters

The 30 meter band is an exception to many of the rules. Only CW and digital modes are allowed on this band. No voice transmissions are allowed at all. It is also not used for amateur radio contests. This is also a small piece of the spectrum, running from 10.100 MHz to 10.150 MHz.

What makes 30 meters unique is that it is the perfect place to develop Morse code skills. The amateur radio operators on 30 meters are there to have conversations in CW, not to make a lot of contacts in a short amount of time, which means newbies can jump in and start learning code at a comfortable speed.

40 meters

The 40 meter band is considered a nighttime band, though some communication is possible during the day. It is located between 7.000 MHz and 7.300 MHz and is not dependent on the solar cycle for much.

It is a popular band; the nighttime equivalent to 20 meters. Contesting and conversations occur on this band frequently. However, this band can also be a little noisy for long distance communication, say outside of the country. As it turns out, amateur radio operators in the U.S. share part of this band (7.200 MHz to 7.300 MHz) with commercial broadcast stations in Europe. Most amateur operator’s 100 W radios are no match for a commercial station with 50,000 W and a large antenna array. Also, during the summer months, lightning discharges generate electrical noise that can make it a little more challenging to hear other radio stations.

60 meters

The 60 meter band is the ultimate example of how amateur radio is an experimenter’s hobby. When the U.S. Federal Commnications Commission (FCC) granted amateur radio operators this band, they set it up a little differently than other bands. Instead of being able to pick any frequency within a specified range, the 60 meter band has five allocated channels.

Besides the channelization, there are several other unusual rules for this band. USB, CW and a few digital modes are allowed, breaking the tradition of using LSB for the lower frequencies. AM, FM and other modes that have a higher bandwidth are forbidden. Furthermore, power limitations are different. Power is limited to 100 W and not measured at the transmitter, but effective radiated power as compared to a dipole antenna. It’s a strange way to measure or calculate power limits, but it’s the law.

80 meters

The next most popular nighttime band is the 80 meter band. Stretching from 3.500 MHz to 4.000 MHz, there is plenty of electromagnetic real estate in which to operate. This band is typically used for domestic communication, though with the right conditions and the right antenna, it can be used for worldwide communication.

Eighty meters is a conversational band, with lots of people “ragchewing” or talking to each other about hobbies, the weather and other such topics. There is some contesting on this band, as well. Another big use for this band is emergency communications, as it covers regions very well, and most states run emergency practice gatherings (nets) regularly on the 80 meter band.

Lightning affects the 80 meter band maybe more than any other band. Before smartphones, storm chasers could use the 80 meter band to determine when a storm had become electrified based on the static crashes. It covers a wider area than 160 meters, so there is a higher probability of getting lightning-generated noise on 80 meters. Eighty meters is often more active in the winter, with longer nights and fewer thunderstorms to cause interference.

160 meters

For the ultimate challenge, there is 160 meters, which occupies 1.800 MHz to 2.000 MHz. This band can be used for contesting, though there are other preferred bands in most cases. Even so, there is an annual 160 meter contest, and plenty of contacts can be made here.

The challenge with 160 meters is that the antennas for this band are large. If one were to make a vertical antenna, it would need to be ¼ wavelength, or 40 meters high. A half-wave dipole would be 80 meters long and need to be 40 meters off the ground, ideally. Because of this, there are fewer operators on this band, as most city and suburb lots are not large enough for these antennas.

Having talked about the challenges, the “top band” as it is nicknamed, can be a lot of fun. With most antennas, it is almost entirely a domestic band, and so talking to other countries can be quite difficult. It is a nighttime band, almost independent of the solar cycle, but it does pick up some lightning.

630 meters/2200 meters

These two final bands are low frequency bands and have similar requirements. They only allow 1 watt of effective radiated power, and are mostly used for experimental purposes.

Some software and online programs can help predict propagation. If the author wants to know when the best time to talk to Cameroon, on 17 meters, he should try between 21:00Z and 23:00Z. Image source: VOACAP

Final Thoughts

Part of the fun in amateur radio is never knowing who is out there and how to get a signal to them. To continue the fishing analogy, some days the fisher goes home empty-handed, and other days, they have an award-winning catch. Amateur radio is like that as well. Sometimes, the perfect setup happens and a mediocre antenna and low power mean talking around the world. Other days, it’s hard to get a signal a few states away or even across town. This article should be treated as a set of guidelines rather than strict rules of operating. For more information, please visit the American Radio Relay League (ARRL).