[TowerTalk] Antenna Testing

[Ward Silver]

As K9YC and others observe, this is a highly non-trivial exercise and takes weeks.  I just do not have the time for the undertaking.  That's actually part of why we published the detailed protocol...so that some other motivated group could build on it.  Another possibility is for one of the big antenna or aerospace companies to make a test range available for a day or two and have a large group do it like Field Day.  But the writeup and data-crunching will still take many, many hours.

K5GO's idea has merit - given the availability of sophisticated modeling, much of the data could be generated computationally.  However, that presumes accurate models that aren't cherry-picked or biased...perhaps third-party models could be developed.  But any model would have to be validated...and that requires testing.  Furthermore, modeling would not have uncovered the problems with the KT34XA trap rebuild kit or pointed out that there might be feed line interaction on the PRO-57B.  And neither do you get a feel for whether the antenna is a mechanical nightmare or exceptionally robust or came with missing or cheap hardware or whatever intangibles that models don't include. So there is no free lunch when you get right down to it.

And there are political issues...I remember the neighbors got mighty nervous when there were five big antennas assembled on sawhorses  in the north pasture :-)  They were greatly relieved to hear that I was only planning a test and some of them offered to help - no doubt to speed its completion and get the antennas on their way.

More seriously, building up a set of data like Rob Sherwood NC0B has done for receivers might be a good long-term project.  Someone would need to make a commitment to maintaining a decent test range in a consistent configuration.  A standard protocol would have to be developed and the equipment to implement it maintained as well.  Over a period of years, a set of data could then be built up for comparison.

On the other hand, with antenna modeling so powerful and ubiquitous, claims of extraordinary performance ("Flash!  Just worked South America!") are much harder to make (more than once) and so the need for third-party checks has been reduced.  I applaud companies that take great pains to publish free-space dBd values with all the necessary supporting data such as elevation angle.  Don't be afraid to ask for that data - if it's not available, take a closer look at the claimed performance and the antenna itself.

73, Ward N0AX