Thursday, August 25, 2011

Reflections on simple antennas-a Hawaii perspective

MOTHER NATURE KEEPS US BUSY

This week has been filed with enough stories to keep any news person busy.  For those of us on Hawaii Island, what was left of Tropical Storm "Fernanda" didn't create any disturbance other than a few windward showers and some higher than normal surf along the southeast shore.  My heart goes out to those facing the trial of Hurricane "Irene"--this looks like a very nasty storm.  It's good to see many people are preparing ahead of time for the storm's arrival or leaving the danger area before high winds begin.  I expect amateur radio operators are gearing up for  whatever Nature throws at them.  Having experienced several hurricanes and tsnuamis in Hawaii, I know these developments should not be ignored.  It always amazes me that there are those who choose to ride out the storm rather than "get out of dodge".  I suppose it's a personal decision, but why tempt fate?   For us in Hawaii County, the passing of "Fernanda" gave us a good chance to assess our emergency preparedness under real conditions.  Like many Hawaii hams, I did a quick inventory of my supplies, made sure all rigs were operational, charged all batteries, and had a few easy to erect antennas ready for the event.  Most of the available antenna books have a section on building emergency verticals, dipoles, and loops.  You might want to build a few easily storable antennas just in case the need arises.

BUILDING THE ULTIMATE ANTENNA FARM...ONE CAN DREAM

While I was reading through the 24 August 2011 edition of eham.net, I came across an interesting antenna website by Tom, W8JI.  This amateur has a genuine, contest antenna farm in Georgia that makes my mouth water.  Apparently, Tom enjoys the challenge of 160-meters and takes steps to realize his goal of being a "top band" big gun.  His 160-meter four-square vertical array is impressive, as are the separate towers supporting a variety of beams, loops, and inverted "vees".  I doubt that I could ever erect such an aluminum forest, but one can dream and perhaps glean a few tidbits of wisdom from this contester.  As I read through his website, I came to the conclusion that my modest inverted "vee" and low-lying loop were useable but not very efficienct.  He backed up his observations with a wealth of EZNEC data and Smith Charts.  I too believe in the "higher the better" philosophy, but, considering the amount of land available for my experiments and the proximity of neighbors and high voltage power lines, such dreams must be postponed until I secure a place far removed from the present qth. 

LIMITATIONS--SO WHAT DO YOU DO?

Rather than be discouraged by the unattainable, I choose to do the best with what I have--limitations nothwithstanding.  One thing I took away from W8JI's website was the importance of cutting feed line losses and establishing a decent radial field for any verticals I choose to erect.  The last time I put up a homebrew 40-meter vertical, I laid out a haphzard radial field consisting of 16 radials of various lengths ranging from 20 to 33 feet.  My yard has definite limitations, so the wire was strung all over the place.  The antenna did a reasonable job and I did get quite a few contacts.  I found the use of 450-ohm feed line, a decent 4:1 balun, and a short length of RG-8 to the old Drake MN-4 seemed to work alright.  The Swan 100-MX remained cool and the SWR stayed below 1.7 to 1.  Nothing to write home about, but the arrangement did work.  My current all-bander (40 to 10 meters) is an inverted "vee" using two 33-foot elements attached to the tip of a 32-foot jackite fiberglass mast.  The 450-ohm feed line runs into a 4:1 balun with some RG-8 connecting the system to the Drake MN-4.  Like my old vertical, the "vee" does a good job considering the limitations imposed by my backyard.  None of my homebrew antenna projects will bust a DX pileup like Tom's Georgia antenna farm, but it  they do allow me hours of endless fun at a reasonble cost.

WHAT'S THE POINT OF ALL THIS?

While I'm impressed by the super stations I see, it all comes down to what you can do within the boundaries of your budget and the constraints imposed by your qth.  Do the best you can with what you have.  The idea is to get on the air and not run your household into the poor house.  If you can afford the build a contest station, do so.  Yes, I want to erect a rhombic and have a set of monobanders at 100 feet.  However, with the economy being what it is, there are more pressing demands, such as paying the rent/mortgage, keeping ahead of the bills, and feeding the family.  Despite all of the challenges of the present day, you can still do a lot to enjoy amateur radio, if you are willing to build some of your own equipment, improve and maintain the rig you currently use, and experiment with antennas designed and built by you.  The key is to study, experiment, build, and use what you have made.  I enjoy the challenge.  There is a certain thrill in seeing where your signal goes once it enters the "ether".  You can experience that sensation whether you are behind an antique like my venerable Swan 100-MX or before the newest Elecraft K3.

So, don't give up.  Get on the air, become the best operator you can, and build your own antennas.  Half the fun is getting there and meeting someone new from the comfort of your home or club station.

Don't forget the Hawaii QSO party this weekend.  Hawaii Island amateurs in the Hilo area will be operating from Coconut Island (Moku Ola) under the callsign AL0HA.  Have an excellent weekend.  Aloha es 73 de from KH6JRM.