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Unlimited space with some limits - questions

Jul 14th 2018, 08:59

kc4rp

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I'm moving to a new QTH and am faced with a set of issues on my antenna selection. Over the past decade or so I have been without any legal restrictions but a few XYL limits that have resulted in using my (in chronological order) my rain gutters (most of Europe and South America), a random length dipole strung up about 80' between 2 pine trees, and a GAP Challenger DX. I like the GAP but my new shack QTH presents issues. Its a 60'x90', 2 story barn that's mostly skinned in corrogated tin. The shack is a framed in and (somewhat ATM) If the GAP is in the ground there would be some INCREDIBLE shading to the North from the barn.

I can run a length of coax out the window to a balun and run some 12 guage stranded as the elements for a randome length, sloping, inverted vee with both elements over 100' in length. Tuning with an old MFJ mechanical tuner to get close enough for the Icom 746 or 7600 to handle it with the internal tuner.

This is looking like my best current option. Vee pointing north toward the barn. Sloping from about 25' to 30' at the wall of the barn to 5 ' to 10' at the 10" fenceposts on the other end. I'll be using 3-4" PVC attached to the posts if above 5'.

Any comments of suggestions welcome. A multi-wavelength Rhombic was considered briefly and discarded. Cost, logistics and the presence of cattle in the fields ranked high in this decision. A tower may happen sometime but not immediately. No HOA to worry about. Just want to get back on the air.
Jul 16th 2018, 09:24

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Too bad you can't make an antenna more effective in all directions by adding wire. A longer antenna is more efficient, but a 100 ft dipole fed with open wire is pretty efficient on 80 meters. A much longer dipole can have gain, but gain is obtained but narrowing the pattern. Which may not be such a good thing if you you only have one antenna between two trees. Also, height makes a big difference at HF--an antenna at 30 feet won't work as well as one at twice the height at this point in the Sunspot Cycle.

The American Rose Society had a problem in that their property was overrun with trees, crowding out the light needed to grow roses. They were able to get someone to take out the trees in exchange for the lumber! Hams may want to do something similar--it is a lot easier to install antennas if you only have a few trees surrounding a large field. Also, it may actually help if the field were a couple hundred feet from the house, as this would reduce noise pickup from nearby electronic and electrical devices. RG-6 CATV coax can be used to inexpensively connect antennas at that distance. Either coaxial adapters or UHF crimp connectors can be used to deal with the aluminum shield of RG-6, which is hard to solder reliably.

I find that three dipoles in a triangle pattern works well for covering all directions.

Zak W1VT
ARRL Senior Lab Engineer
Jul 30th 2018, 20:13

kc4rp

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
The office I'll be using is on the upper floor of a barn and is at least 100 yds from the main house. Still thinking of the wire antenna as a temporary and maybe going to a GAP or Hustlet 2m - 80 M vertical in a few months depending on what we have grazing there. Goats or Alpacas I don't worry about as much as 500 lb or more steers. However, if the wire antenna works well, I'll keep it.

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