Friday, July 24, 2015

Introducing VOACAP DX Charts

UPDATE July 2017: MUFday assessments in place for all HF propagation prediction tables, resulting in even better predictions on Above-the-MUF frequencies. Read more!

After I have now more or less finalized the VOACAP Propagation Planner service (...for now...), I decided to create a spin-off service that calculates short-path (SP) and long-path (LP) HF propagation predictions from the user's QTH to some of the upcoming DXpeditions.

I call this service 'VOACAP DX Charts', and the address is : . This service of course uses much of the same technology I created for the Propagation Planner such as:

  • interactive propagation charts that show the QSO probabilities and signal power (hover the mouse over the table cells to see the values)
  • graphical presentation of sunrise and sunset times to help predict low-band openings (hover the mouse over the 'TX' and 'RX' labels on the bottom left of the tables to see the exact sunrise and sunset times in UTC)

An example DX propagation chart.

Added April 28, 2017: 60 meters!

I have deliberately kept the layout of the results page to a bare minimum to allow the user to copy the charts to word processing, and make them pretty for printing.

To use this service, the user only needs to know his/her Maidenhead grid locator and press the "Run!" button. If you do not know your grid locator, I have created an easier-than-the-easiest Google Map application to help you find your grid locator : . Just zoom into your location on the map, and your coordinates and grid locator are readily visible on the top part of the map.

For the predictions, I have assumed that, on 20M to 10M, the DX uses a 3-ele Yagi at 10 meters AGL, and on low-bands a 1/4 vertical over a good ground. On the user's side, a 3-ele Yagi at 20 meters AGL for 20M to 10M, and a 1/4 vertical over a good ground are assumed.The TX power used is 1.5 kW.

Currently, the following DXpeditions are included:

  • TI9/RA9USU, Cocos Isl (Jul 2015)
  • K6W, Wake Isl (Sep 2015)
  • TX3X, Chesterfield Isl (Oct 2015)
  • 3B9HA, Rodrigues Isl (Nov 2015)
  • 3C7GIA, Equatorial Guinea (Nov 2015)
  • VK9WA, Willis Isl (Nov 2015)
  • 3Y0F, Bouvet (Dec 2015/Jan 2016)
  • KH5, Palmyra (Jan 2016)
  • VP8SGI, South Georgia (Jan 2016)
  • VP8STI, South Sandwich (Jan 2016)
  • FT/J, Juan de Nova (Mar 2016)
  • VK0EK, Heard Isl (Mar/Apr 2016)

Please let me know if you find bugs, or want more DX sites to the list.

73 Jari OH6BG


  1. After the Point-to-point prediction, the Coverage Area map, the blog, the Planner, with this DX Chart VOACAP online - and always free - becomes a must for all fans of propagation. Congrats to Jari Perkiömäki, OH6BG/OG6G, and his team who support this new version !
    About VOACAP read :

  2. ANy chance of building charts for the guys currently in A25? I haven't heard them at all as yet, neither LP nor SP.

  3. Hi Gary, yes the charts have been updated accordingly :)

  4. HI Jari!
    Can you add my next dxpedition 15-27.03.17. S21GM
    73, Yuris/YL2GM/

    1. Absolutely, thanks for the heads-up!
      73 Jari OH6BG

    2. S21GM predictions now available at

  5. Hi Jari,

    Could you add PG400TH predictions as well?
    Please have a look at

    Tnx and keep up the good work.

    Jan, PA2P

  6. Hi Jan, please contact me directly via email, and let's talk.
    73 Jari OH6BG

  7. Hi! Jari

    Kindly add our coming dxpedition 29/4-1/5/2017 at Satang Besar Island, OC-165. Grid: OJ51BT. Callsign: 9M8RC

    de 9W8DEN