[NLRS] Antenna Height Question

[Jon Platt]

The extra 70' of LDF-5 on 222 (the higher band) results in about 0.4 dB of additional loss compared to the shorter run.  That may be important for EME, probably not for terrestrial.  Also to consider may be the ease of continued maintenance and rotator capabilities.  Having been to your place once I recall that its relatively flat so its not like you need to get over a hill or ridge.   All that said, I have heard antidotes from VHFers over the years about having such high antennas like your 140' being able to get into tropo ducting while lower antennas could not.  YMMW.

I don't think you can go wrong either way.  Myself, without knowing about those intangibles, I would go with the tall tower, but, I don't think the lower installation is a "bad" one either.
Sounds like a good problem to have Mike !   
73, Jon

-----Original Message-----
From: Mike Cizek W0VTT <mgcizek at gmail.com>
To: nlrs at mailman.qth.net
Sent: Fri, Apr 2, 2021 11:23 am
Subject: [NLRS] Antenna Height Question

Greetings,

 

Some newbie questions from an HF guy installing antennas for 2m and 222.
Both are M2 5WL Yagis (thanks Vince!).  I have two options for installing
these antennas:

1.    At 35' and 40' (more or less) on a short tower.  ~ 130' feed line
length; LDF-5
2.    At 135' and 140' at the top of a long mast sticking out of a 125'
tower. ~ 200' feed line length; LDF-5

My first thought was that since this is VHF, higher is better. (period) I
can easily put one on the short tower for testing, and plan to do that for
the sprints this month.  I modeled the antennas at both heights, and was
surprised at how similar the patterns are even with the 100' difference in
height.  The main (lowest angle) lobes are only a few degrees of elevation
and fractions of a dB apart.

 

Other than greater line-of-sight coverage, is there any real advantage to
mounting the antennas 100' higher?  My main goal is new grids for VUCC on
both bands.  

 

Thank you.

 

----

73,

Mike Cizek W0VTT

 

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