By AA6J Bill Jeffrey
Assistant Scoutmaster and Merit Badge Counselor
2. How do radio waves travel?
Sketch a diagram showing how radio waves travel locally and around the world.
Line-of-sight where the antennas can "see" each other. (You to #1 in this picture)
If a hill is in the way, a repeater on top a mountain or building can relay the signal over it. (You to #2)
High frequency (HF) radio bounces off the ionosphere long distances (You to #3) (Skip)
Signals can also be relayed by satellite or even moon bounce or meteor trails.
HF radio propagation is affected by radiation from the sun, so different frequencies work better at different times of the day.
How do the broadcast radio stations WWV and WWVH help determine what you will hear when you listen to a radio?
WWV in Colorado and WWVH in Hawaii broadcast the time on several frequencies. By listening for these stations on their regular frequencies you can tell how good signals from those states are on the different radio bands.
Time is given in Coordinated Universal Time (UTC), also known as Greenwich Mean Time (GMT) or Zulu (Z), which is eight hours later than Pacific Standard Time. This avoids confusion in having to know the local time zone.
|These notes are designed to help the Scout earn a merit badge that sometimes can seem a bit difficult. They are not intended to replace the Radio Merit Badge book.You will still need to meet with a merit badge counselor.|
2Links about this requirement below:
Copyright Bill Jeffrey 2000-2001. Rights to
reproduce and use for nonprofit purposes given.
Please do not copy this material to another web page. Thank you.
UTC-GMT Conversion by DXing.com has a good explanation of world time (UTC), and a chart to convert UTC to the time in the 48 United States.
Propagation predictions can be hard to understand. If you want to try, look at Ae4RV's Simple HF Propagation Primter.
AC6V's DX & Amateur Radio - My friend Rod has the world's best collection of links to amateur radio information.
Last update October 6, 2001