Posts Tagged ‘antennas’

Review: Array of Light (3rd Edition)

July 9th, 2013

My friend Matt, KB9UWU, eggs me on to buy things.  Sometimes I listen.  Sometimes I don’t.  But, eventually he wins me over and I’m usually happy with the purchase (e.g., K3 and Hex beam, although I built the Hex from scratch, which reminds me that I owe the blog a discussion of that).  I like to think that I let Matt be the early adopter and then pick and choose based on his experience.  He convinced me to buy a copy of N6BT’s book Array of Light.  Here’s my review.

If there’s anybody that knows antennas in the amateur community, it’s Tom Schiller, N6BT, the founder of Force12 and now owner of N6BT Next Generation Antennas.  He’s also a member of the very successful Team Vertical contest team, who have revolutionized DXpedition and contest expedition antenna systems by replacing trapped tri-band Yagis like the TH-3jr(s), TA-33jr, and A3S, with arrays of verticals located at the water line.  Schiller’s work has been nothing short of revolutionary so I had high hopes for the book.

My copy, like every other copy, is signed by the author.  It’s a good-quality laser print and has the same spiral binding as the Elecraft manuals.  The book is a loosely-edited collection of articles and clippings that read pretty well in series.  But, it’s bear to skim or go back to find specific things unless you’ve read the whole thing cover-to-cover a couple of times.  But, that’s pretty easy to do because Tom is a good storyteller.  My only other complaint is that there are a couple of places where I think Tom has drunk his own Kool-Aid regarding the efficiency of his antennas, especially “linear loading.”  This is a topic that I need to revisit with a pencil and paper study at some point because there is a lot of misinformation floating around about traps, linear loading, and “multi-monoband” antennas.  It’s not clear to me that anyone has sat down and really examined this in a methodical way.  It was disappointing that he quoted numbers like “greater than 99% efficiency” without going into more detail about the efficiency of a full-size antenna versus the linear-loaded one, etc.  Of course, this is difficult, but it’s something that always makes me a bit skeptical.

Array of Light is worth the price of admission for a couple of reasons—the first is the stories and the second is the antenna designs.  I’m a big proponent of not reinventing the wheel on most of my homebrew projects and this book is sure to provide some proven designs to work with.  Especially if you want a good discussion of practical antennas for DXpeditioning and contesting I think it’s a real winner.

More Hexbeam

February 25th, 2013

hex-gym

“What have you done to my play set?”  This gym made a convenient place to string wires, etc.  Two poles in the photo form part of the EWE RX antenna here at K8GU that was hastily erected before the NA Sprint CW.  One of the poles is ty-wrapped to the play set.  Doing my best to keep it klassy and impress the neighbors.

hex-up

And, we’re up in the air!  The M2 9M2SSB is a little bit out of alignment due to the hex getting tangled in one of the antennas that it was due to replace.  I have already realigned that.  So far, the antenna seems to have useful front-to-back.  Gain is hard to tell since I took down all of the antennas it was to replace.  But, it does seem to work.  I’m suffering from high SWR (above 3) on both 21 and 50 MHz.  G3TXQ warns of interaction between 18 MHz and 50 MHz.  Do not yet know the cause, but I’m looking into it.

Although the antenna is relatively easy to handle, I don’t plan to make a habit of taking it down for work.  Speaking of taking down, the 40m dipole whose center insulator is just visible behind the reflector of the 2-meter beam will be replaced by an as-of-yet-secret antenna.

Hexbeam Photos

February 12th, 2013

  

Construction project:  G3TXQ hex beam built from scratch.  K4KIO directions with K8GU modifications (and reverse-engineered square coaxial center post).  Details to follow once I determine it works to my satisfaction.