What is DX?

 Amateur (Ham) radio operators can be a weird bunch.  I can say that because I have been one for 53 years.  One of the most popular facets of the hobby is to contact as many distant (DX) stations as possible, specifically countries, or as we refer to them now, entities, as many are not countries but islands usually under the control of another country.  There is some sort of criteria, but as of today, there are 340 different entities.

A good number of these entities have no permanent population, like Bouvet Island in the South Atlantic ocean, or Clipperton Island in the Pacific.  Some may be populated but have no ham radio operators.  So ham radio operators will recruit a crew of operators, take equipment food and supplies, and maybe charter a ship to go to them.  This is called a "DXpedition".  Then over a period of days or weeks, contact as many stations as possible.  A valid contact is an exchange of callsigns, and a signal report.  Because they are trying to allow as many stations as possible to contact ("work") them, they usually only exchange this basic info.  Contacts can be voice, Morse code ("cw"), or a digital contact which uses a computer and a soundcard to decode the info.  (BTW - Morse code is no longer a requirement for an amateur radio license.)

There are a number of ways to recognize stations who have contacted the most entities, but the most popular and accepted way is through the USA based ARRL (American Radio Relay League).  Contacts have to be validated, which can be by a QSL card, which is a postcard type document exchanged between stations after a contact is made.  This was how it was always done, until the last 20 years or so, when this can be done electronically.

In my first 45 years or so of ham radio, I liked to contact these DX stations, but never really put much effort into it.  Plus school, work, family, bills, etc.  I had contacted maybe 80 or so countries over the years.  Retirement has given me more time.  As of today, I have worked 227 countries, with 217 confirmed.  I have a friend, Bob, who lives in Webster, who has worked and confirmed 339 out of 340.  North Korea is the only one he is missing.  Safe to say, no one wants to mount a DXpedition to there.

Radio waves capable of going across the globe are affected by many factors.  One of the biggest is the sunspot cycle.  For radio waves to propagate beyond line-of-site, and follow the curvature of the earth, they must be bent or "bounce" several times off the ionosphere, which is about 80 - 600km above the surface of the earth.  The physics of the phenomenon are beyond this, but it correlates to increased sunspots which is on an approximately 11 year cycle.  We are presently about 2/3 way between a minimum and maximum.  At minimum, long distance contacts are less common.

The ability for radio waves to reflect off the ionosphere also depends on the radio frequency being used.  Typically it works in the area dubbed "shortwaves", from about 600 Kilohertz to 30 Megahertz.  This is an area from the AM broadcast band to something short of the FM broadcast band (88 Megahertz).  Today, even shorter wavelengths are used for communication, but typically are short range on earth, but used for satellites or in space for longer distances.

All of this can be done without great sums of money.  Antennas are a big factor, and though simple wire antennas can be quite effective, bigger is usually better.  Unfortunately bigger may not be aesthetically pleasing, and apartment or condo living, HOAs, deed restrictions can make it very difficult. But I had a friend who lived in a one story townhouse, who had contacted a couple hundred countries using antennas in his attic (no attic rafters, just roof trusses).  So people can find ways.

That said, hams will often build a station around working DX.  State-of-the-art transceivers, huge directional antennas, towers, amplifiers, etc.  Antenna theory, design, and performance are also a popular facet of the hobby that hams are always experimenting with.

Though most contacts with DX stations are brief, I usually will visit their ham radio home page on QRZ.com, which most active hams around the world can use for free to display information about themselves, their country, or their stations.  Since I always have had an interest in geography, I will also visit the Wikipedia page about their country or island.

Though QSL cards have mostly been supplanted by technology, today I received a QSL card from Vietnam, which took about 5 weeks to get here via mail.  One of the many reasons I enjoy the hobby.