[Elecraft] antenna farm

Mon Dec 14 16:29:42 EST 2009

Hello Clint and welcome aboard,

Your ultimate ambitions and desires will have to take second seat to the restrictions of your location.  Not withstanding antenna/tower height restrictions in the county and city you are in.  

First off, being able to select a compass quadrant on a small lot is probably not possible, unless you can erect a tower or have enough room for a 4 square or even a 2 element vertical.  Wire beams take ROOM.  Even an inverted V on 80 meter is at least 95 feet across the bottom.

Ok, enough negative thinking. Some observations.  Many bands are open to different areas of the world at different times of the day.  Gray zone etc.  So on 160, 80 and 40 meters paths are likely to be very good in one direction and not so good in the opposite.  Get the idea?  

I would consider your "antenna garden" a work in process and start with something that works good with the space you have and develop a plan to see what you can work and when.   A years worth of investigation will tell you a lot on where the conflicts are and where the sweet spots are.  

So where do you start.  A good dipole for DX should be at least 1/2 wave above ground and the DX'ers won't even do it that low.  That is 120'+ on 80 M etc.  Ok, an inverted V can have the apex lower, like 50 to 60 feet. so you still need a center support.  You can do this and feed the inverted V on multiple bands with a little clever work on the feed line length and a good match box. Or you could put in traps in the inverted V for other bands and loading coils for 160.  Not super class but functional.  Frankly I would start there.  It is the simplest and most effective antenna for a small lot and a conservative budget.  

After a season with this, you can decide where you want to "grow" your farm and on what bands that your budget can afford.  Good luck.

Mel, K6KBE

--- On Mon, 12/14/09, Clint <clint.stark at sbcglobal.net> wrote:

From: Clint <clint.stark at sbcglobal.net>
Subject: [Elecraft] antenna farm
To: elecraft at mailman.qth.net
Date: Monday, December 14, 2009, 10:17 AM

Fellow Elecrafters,

I have a feeling this may open the flood gates but here goes.

I am a newbie Ham but a long time SWL going back to my Knight Kit Star Roamer. I am fixin' to set-up my antenna farm. OK, it will be more like an antenna garden as I have a small house and lot. My K3/100 has a KAT3 and KRX3. I plan on using 3 Dipoles and maybe an inverted V for diversity receive (what a great feature).  I got on Google Earth and plotted out the areas I am interested in. I live just up the street from Elecrafts new HQ (talk about fast service) on the central coast of California (CM96CX).

A bearing of 118 deg (antenna runs from 28 to 208 deg) cuts across Central America and South America on one side and across Manila and Singapore, skirting Japan, on the other (298 deg). This is a great coverage for me as I used to live in Singapore and spent lots of time in Asia (work) and Central America (not work). 

The next one is 32 deg (antenna runs from 122 to 302 deg) which cuts through London and Rome on to the Middle East. The other side is not too much, Tahiti and the South Pacific. I am thinking of a reflector on this one as there is not allot at 212 deg that interests me and that should help with Europe, I think.

The next one is 78 deg (antenna runs from 122 to 302 deg) which cuts across the US through North Carolina, Bermuda and on to South Africa. The other side, 258 deg, runs through the Solomon Islands and right down the middle of Australia to Perth.

I know the lobes will spread way out from these bearings over these long distances but these numbers are a starting point. The antennas will also cross forming a pattern similar to an asterisk on my roof/lot, a good thing I am guessing.

I was thinking about Inverted V's for most of these until I checked what the side lobes would pick-up. On the 118 deg antenna it would be the South Pacific (no problem) and Europe (big interference problem while shooting for C/S America and SE Asia). 

The 32 deg would pick-up Japan, SE Asia on one side lobe and Mexico, Central America on the other. Too many unwanted signals if I am trying for Europe. 

The 78 deg side lobes would pick-up Alaska, central Russia and west India on one side and the South Pacific, places like Pitcairn, and on to Antarctica. Maybe an inverted V would be OK on this one.

The Diversity may be a big inverted V or just an L shape long wire. I laid out a spread sheet with the lengths for a Dipole plus 15 deg, 22 deg, 30 deg, 37 deg, 45 deg, 60 deg and 75 deg inverted V's from 160 to 2 meters using the center of the Extra class bands (my next conquest) looking for some magic number. Nothing jumps out at me but of course a ¼ wave 80 is close to a ½ wave 40, a ½ 60, ¼ 30 and so on. I think I can squeeze in a ¼ wave 80 meter dipole (~31.2 feet/side) in most directions and maybe a shorter one above this (easiest for me but technically wrong?). The longer one higher may be possible but won't be easy. 160 meters will be another project for another day.

So my questions are:

1)      What length would be best and give me the use of the most bands? Remember, I have a limited space.

2)   How far from the dipole should a reflector be. It should be about 5% longer and grounded, right?

3)      The auto-tuner on the K3 is amazing. Is it easier for it to tune an antenna that is to long or to short? I'm guessing long but I am not certain. 

4)      Any suggestions on which band/antenna length is best for these targets? I am mostly active late afternoon and evening (till about 10 PST) and mornings after 6.

Thanks, 

Clint KI6SSN

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