[TowerTalk] How high is high enough? (my recent experiences, long)

[David Clemons]

Hi,

        At one time or another, most serious ops probably wonder if their
antennas are high enough.  Usually it is a big job to change their heights,
but we worry anyway.  I'd like to pass on some interesting observations
concerning an actual change of heights.

        I recently had to do a major construction job on my towers/antennas
/rotors.  The most obvious change was that each of my monoband yagis
(10m-40m) were moved to lower heights.  The original heights of these
antennas were what I had considered to be optimum single antenna heights,
which I came to after talking with a lot of people and reading a lot of
articles.  The heights:

                band    old hght         new hght
                ---------------------------------
                  10       83 ft            63 ft
                  15       89 ft            69 ft
                  20      105 ft            91 ft
                  40       99 ft            85 ft

I changed the spacing of the 10m HyGain from BA to CA model, but left 15 as
a BA because of its better swr across the entire band.  The 20 and 40 ants
remained the same.  My initial thoughts were that I was probably going to
suffer in DX contests, mostly on 10 and 15 in lower sunspot years, but that
I would perhaps do better in domestic contests.  If this became a real
problem, next sunspot low I could replace the 10 and 15 with a quad at the
same height.

        I then entered two contests (IARU CW ONLY and NAQP CW).  I believe
the solar flux for IARU was a couple points lower than last year, and for
NAQP identical with last year except that the A index might have been
higher this year.  A comparison of my performances:

        IARU - total score higher this year.  Only 30 more qsos, but a much
               higher percentage of 5 point dx qsos.  Operating strategy
               was the same.  A comparison against my friend Bill N1BB
               (operating at W1KM's super station) showed him doing much
               better, especially on 15,80,160.  His antennas on the latter
               two bands are phased verticals, on 15 he has more height and
               probably stacked yagis.  Overall, I was pleased.  Bill was
               officially a MS, although he did almost all the operating
               (and with no packet) and thereby is a good comparison against
               a single op.  (The super station notwistanding, Bill is also
               a great operator.)  According to the 3830 list, my score will
               perhaps rank as high as #4 in the US.

        NAQP - we appeared to have short skip on 10/15/20 much of the time.
               I never remember working so many stations east of the Miss.
               on these bands.  40 also worked out quite well, but I sort
               of expected that.  My total score was more than 50% higher
               than my previous best.  It seemed that I was almostly
               constantly being called by several stations - truly an
               unusual circumstance for me in domestic contests.  I have
               received several e-mails telling me how loud I was (remember:
               this was a 150 watt contest).  Please, keep the compliments
               coming  :-).  I am sure that most of the high score was due
               to the unusual propagation, but certainly the antenna
               changes seemed not to have caused any detrimental effects.

        Obviously it is too early to make a final analysis of the effect of
these changes.  However, I am quite pleased at experiencing what seems to
be performance not much less than at the previous heights.  By the way, the
minimal effect of the height change (especially 20 and 40) seems to agree
with the analys of expected radiation angle changes which I received from
Dave K6LL.  So, for others who find their antennas to be lower than what
they'd really like, take heart.  It is quite likely you will at least
sometimes experience unexpectedly good results if your antenna is at 80 ft
instead of 100, 60 ft instead of 80, 40 ft instead of 60.

        The beauty of this hobby is that with propagation changes, antenna
changes, etc., you can spend years discovering new things before you really
understand the big picture.  I find the learning experience to be quite
exciting.

73 Dave Clemons K1VUT

p.s. The best part of this, IMO,  is that this is not an April's Fool joke!

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