Ideas for 160m wire antenna on a small lot

[Moleculo]

I've been trying to come up with ideas for a 160m antenna on my small lot in the city for some time. I've thought about a loop, inverted L, etc. but haven't come up with an idea that seems like it will work in such a small space.

Here's what I'm currently thinking, but I'm not sure complete how to make it work, or if it even will work.

Here are the tools I have to work with so far:

• 30' push up mast on the center of my roof. Roof is 12' tall. The mast currently has a inverted V dipole and Cushcraft R6000 above it. Dipole and vertical are both fed with coax secured to the mast
• Approx 30' Palm tree in the back corner of the lot. The palm tree will eventually grow 70-90 feet tall, but this will take years. The palm tree is also in close proximation to the power feed line for the house, although that feedline is on the property border.
• 25' tall Juniper trees that are on the opposite border from the palm tree, also in the back yard. The trees line the border and actually butt up against one corner of the house. The inverted V is actually tied off to the tree closest to the house.
• Rain gutters around the house
• Chain link fence on the back property line, but it's below the power lines.

I was thinking about attempting to load up the push up mast, hoping that the Cushcraft might act as a small capacity hat. Then run some wire over to the palm tree, about 30 feet away or so. That's only 60 feet of wire, so I was wondering what would happen if i run the wire down the palm tree and terminate it with a large 50ohm resistor in case I decide to throw a couple hundred watts into it. That still doesn't seem like enough wire, in the air though.

Ground radials are a problem also. I could run a few down to the rain gutters, perhaps then run from the down spouts into the yard, but it would be a compromise at best.

What am I missing to make this idea work? What about the feedline that is secured to the mast? Isn't it going to pick up the RF and cause me other problems? If it will work, what's the easiest way to load up the push up mast? Keep i mind that I can run all of this into a tuner, if necessary.

What are some other ideas to get on 160m with what I have to work with?

 

[EDUK8TR]

Mole,

I have a 40m Horizontal Delta Loop strung up in some large oak trees, that is fed with about 55ft of 600 Ohm ladder line down to a 4:1 DX Engineering balun. From the balun there is about 12 ft of RG8 into my basement shack to my tuner. I never have been able to get the LDG AT-1000 to tune up the 40m loop on 80m or 160m. There is a neat trick that I got from the ARRL Antenna book. When I want to work 80/160 I go outside to where the balun is mounted on the outside basement wall and take the negative side of the ladder line and short (connect) it over to the positive lead of the balun. I have a wire that is connected to the chain link fence which goes around the back yard that I connect to to the negative post of the balun. As a result the ladder line radiates as a vertical with the loop acting as a cap hat with the fence acting as a counter poise. This configuration will load up with the AT-1000 and works great on 80/160m. Not sure if this would work in your situation but it is something you can think about.

Hope this helps!

73

Wayne C.
WV4L

 

[C2]

OK, if I'm looking at your lot right, and I think your power lines run along the back, I can see the palm in the lower left corner. Here is what I would do,

Run an inverted L wire fed at the base of the palm, straight up as high as you can get it.

Then go to the opposite front corner of the lot (top right, across from the driveway) and install another mast about 60 feet tall, or as tall as you can. Put a 10-foot or so PVC on top of that and connect the end of the wire inverted L there.

You can add some loading coil at the top of the palm if the electrical length is not long enough.

Now, at the feed, run some ground radials to the fence running along the back, if that is where it is, or to wherever it is. Also, run some ground radials to your cold water supply and along the fences at the ground around the palm.


Now, if the 60 foot pole at the front corner is not doable, I guess you could reverse it and do like you originally thought by running from the house back to the palm, but I would probably do it from a mast at the front corner of the house. Again, adding a loading coil at the top at the bend.
HTH

 

[C2]

BTW, I run an 80 meter inverted V from corner to corner, about 10 feet up, and a mast in the center about 60 feet up (40 foot push-up pole on top of the house) and it loads 160 with my MFJ tuner.

 

[W5LZ]

How about something like this? Figure the perimeter measurement of your lot, using trees as the 'corner' antenna supports (wire strung through them). The two 'magic' number for 160 meters is '256 feet' (1/2 wave +/-), and '550 feet' (full wave +/-). Does that distance around your place get sort of close to either of them? Not absolutely in a straight line, but any sort of 'odd' shaped thingy, or a loop, maybe? See where I'm going with that? Won't be the absolute most bestest thing in the world, but it beats nothing.
- 'Doc

 

[Moleculo]

C2, you have the general idea of the layout of the lot.

A couple of things to add:

• The wife says antennas / wires going into the front yard are off limits. She puts up with all my other radio stuff, so I kinda need to oblige her on this one.
• I did at one time have a full wave 80m loop feed by ladder line that was laying on the roof, along the fence, through the trees, etc. I never really was able to load this up on 160 unless I shorted the ladder line and made that part act like a vertical and the loop like a giant cap hat
• I did at one time short the coax for the inverted V and got that to load up. Again, that's the same as a vertical with a cap hat.

The problem with the two scenarios above was the ridiculous amount of RF in the shac since the vertical element was so close to the station.

 

[rfoverlord]

Mole, I run a homebrewed "cobra ultrlite" 30ft apex and the ends are on poles 16ft off the ground as an inverted V it loads up on 160 and is great on every thing else. I made it out of rad shack rotor control wire fed with 32.5 ft of 450 ohm ladder line going to a DX Engineering 1:1 balun (or was until the support on the tower snapped in the last snow/ice storm we had) The mounts for the wire was made out of scrap plastic total investment was about $30 and half a days time for the antenna itself.

I probably should have added that the tower is in the back yard centered 30ft. to each side and the legs go out to support poles 95ft. go to the fence line 85 ft. away

 

[BJ radionut]

160m antenna experiments

Mole: Here's a couple things I have tried over the years and got them to work...Not optimum by any standard but it got me on.
Your 80m loop space...install an insulator at the center point of the loop...you now have a "BENT" 160m dipole...
I had the best luck using Ladder Line plus stretching the loop a little so the ends were where I installed the insulators about 10-15 ft apart...make any sense?...
Then run a jumper wire between them to reconnect the loop for 80m.
I settled on the Ladder Line (instead of coax) as this solved the SWR silliness between the 2 bands...but did get it to work with coax by dropping vertical tuning stubs from the insulators down about 20 ft...but just got to be to much hassle when I wanted to go back to 80m...go out in the yard run the jumper across and then remove (unclasp the stubs) again...etc...

Number 2: This worked also...Never seen where anyone else had tried this, but again with the tuner I got on...
Using all Ladder Line...
I had just enough room plus a smidgen more for an 80m "V" dipole...went about 70ft out from my mast and shorted the ends of the Ladder Line. This made each leg of my dipole about 125ft long (just folded back) This left the "folded" back ends about 15ft from the mast on both sides
I put a egg insulator there and tied them off to the house and a tree so they did not twist and kink.
Best I can call this is a "Double Marconi"
I hope this makes some sense...If not, I can draw a picture of how I did it...(I always was a picture is better than my words kinda guy):tongue:
Anyway you might get a better idea from these couple of things I did.
Good Luck
All the Best
BJ