Propagation...What Is That

  I remember hearing people on the 11 meter band way back in 1977 from states hundreds of miles away and then I could barley hear someone 30 miles away. I remember having a basic understanding of how the radio signal would go up to the air and bounce off the ionosphere layer of air and come down at the same angle thousands of miles away.

By F1jmm (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

             Antenna Propagation shown above

Since being a Ham Radio operator in June 2010 I have learned to understand it better and appreciate it. I am always fascinated when I hear someone from another country across the ocean. The sun plays an important effect on how the propagation of radio signals are going. I have also found that different times of the seasons will have a direct effect on the propagation of radio signals. The winter time tends to be much quieter than during the summer. This is due to the position of the sun being closer to the earth.  The other factor is the time of the day, while during the day there is more activity then at night. Once again this is associated with the sun. Below are some photos of solar flares from the sun.

Sun Spots and Solar Flares

Solar Flare

  Sun Spots and Solar Flares can also affect the radio wave propagation. It can affect us in a good way and then it can be in a bad way. Here is a good article from ARRL http://www.arrl.org/here-comes-the-sun . The ionosphere will affect different wavelength frequencies in different ways. It will reflect the high frequencies, but allow the vhf frequencies to pass through. This is because the vhf signal with fro example 100 watts carries more energy then a high frequency signal with the same amount of power. If you really want to understand this then I would suggest studying plasma physics.
  There are many websites out there can give current propagation, space and weather conditions. Here is a link to a website with some very helpful and informative information http://ve2xip.cactus.net/?p=1676 . You can find many charts that will give current conditions such as the photo below.

  Here is an excellent website that gives plenty of current solar information http://www.solarham.net/ .

  
 

By NASA Goddard Space Flight Center [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

   Here is an excellent free e book by Steve Nichols and Alan Melia in pdf form I found on the internet. Here is a link to the website http://g0kya.blogspot.com/2010/11/understanding-lf-and-hf-propagation.html .
  My understanding on the propagation is somewhat basic, so I hope the links I provided will give better information.
  There are some very good free propagation pieces of software available on the internet. One of these is called VOACAP and can be downloaded at http://hamwaves.com/propagation/software.html . Another good free program is called VOAProp and can be found at http://www.g4ilo.com/voaprop.html it will require VOACAP to be installed first. Ham Cap is another fine tool and can be found at http://www.dxatlas.com/HamCap/ . I also found W6ELProp at http://downloads.fyxm.net/W6ELProp-77810.html . These programs are a few years old, but look good. Here is a newer program from this year 2013 and  it can be found at http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=7969 .

  Well once again on a final note I hope the provided information is helpful.
  Thank You for reading 73s from Dan KC2YTI