Tuesday, June 18

Chapter 5: Single Sideband Range

Table of Contents

Your transmitted ground waves are seldom influenced by atmospheric or ionospheric conditions. Here is what to expect in ground wave range, 24 hours a day:

SSB Ground Wave Range

2 MHz 150 Miles Anytime Day or Night
4 MHz 100 Miles Anytime Day or Night
6 MHz 75 Miles Anytime Day or Night
8 MHz 70 Miles Anytime Day or Night
12 MHz 50 Miles Anytime Day or Night
16 MHz 50 Miles Anytime Day or Night

VHF Band (156 MHz) – 8 miles vessel-to-vessel, 25 miles to Coast Guard

Sky waves give you the very longest range, thanks to the ionosphere. Here’s what to expect in solid communication range to distant ship and shore stations:

SSB Sky Wave Range

Frequency Band Day Time Range Night Time Range
2 MHz Sky waves absorbed 1,000 Miles
4 MHz Sky waves absorbed 1,500 Miles
6MHz 500 Miles 2,000 Miles
8 MHz 700 Miles 3,000 Miles
12 MHz 1,500 Miles Worldwide in the
direction of the sun.
16 MHz 3,000 Miles Worldwide in the
direction of the sun
until 8 p.m. local
22 MHz Worldwide Little sky wave
reflection after sunset.
25 MHz Worldwide Little sky wave
reflection after sunset.

As you can see, to talk further, go to a higher frequency. However, watch out—you can sometimes select a frequency that is too high. This may cause your sky wave signal to actually bounce over the station that you wish to communicate with, or go off into space.

If your signal is literally skipping over the desired station, switch to a lower frequency.

After a few weeks of tuning your receiver to different stations, you will be able to anticipate which band will be the best for a particular time of day to talk to a specific station hundreds or thousands of miles away. Try tuning your set during the day, and then at night, and listen to the difference in range. Switch between bands and begin to get a feel for how the ionosphere causes signals to skip long distances, and sometimes short distances.

Marine telephone shore stations make it easy to predict the best band to establish rock-solid communications. Every four hours they read a traffic list (calls being held for vessels at sea) as well as ocean weather conditions. They simultaneously transmit this information on each one of the authorized bands. Simply switch bands while they are transmitting and determine which band offers the best reception. Where you hear them loudest is where they will hear you best. After they finish with their traffic list, give them a short call and you have now established communications, thanks to sky waves and Mother Nature‘s reflective ionospheric mirror.