160 meters, limited space ideas?

[Moleculo]

Last night I decided to try and fool around on 160 meters. Not having a huge amount of space for long wire runs, I decided to try and load up what I have. Here's what I did:

A. Took the inverted V multiband 80m dipole, shorted the coax at the transceiver end and fed as a long wire into tuner. This loaded up pretty easy, but the performance was terrible.

B. Took 80m loop fed with 450 ohm ladder line, shorted ladder line at transceiver and tuned as long wire. This worked pretty well, and I was able to have a nice converation with someone about 30 miles away. I was not able to copy the station using method A.

My 80m loop is very low...It's on the fence, through the trees, on the roof. The noise floor is very high because of that. While I was getting a S9 from the other station (at 100 watts), he was only getting an S3 from me (same power level).

So now I'm looking for other ideas. How about some space & height limited antenna ideas for 160 meters? I can run power if needed, so in this case the RX is the biggest problem to overcome, I think.

 

[Guest]

Geez this server is slow. :roll:

Put up as much wire you can in a loop, and feed it with 600-ohm open feeder. A triangle shape is okay too, but the radiation pattern will be effected. You have to get this as high as possible.

Or... End feed a wire with a 1/4 wave stub as a counter-poise.

NEVER use coax to feed a multi-band doublet. The losses are phenomenal.

160 meters is not a "I dont' have a lot of room band", you'll have to make due. Try a big loop. String it over whatever you have.

 

[W5LZ]

Mole',
I think your 'B' is about average for those not on 160 meters a lot, Not exactly 'good' by any means, but sort of average. "181" has is right, 160 just isn't one of those bands you can 'make do' on real well, it takes either lots of room or a loaded antenna.
One thing you might try if you've got the room is a loaded inverted 'L'. Doesn't necessarily need a huge amount of wire in the air, but does require at least a 'fair' ground system. Sort of doubt if it would be considerably better than the 'shorted' loop, but an option. Or huge loading coils and a sort of 'mobile' antenna kinda thingy (another one of those 'options' but not a good one). Height makes 'right'. And is that an exageration to some extent! Getting your loop up higher is at least as good a bet as the other 'options' I gave.
- 'Doc

PS - The only 'decent'(?) contact I ever made on 160 was with a 1/2 wave dipole that was every bit of maybe 6 feet off the ground. (out at the lake, no good sized trees, had a spool of wire, no insulators, and lots of time. Miracle or miracles, it worked. About as well as my chances at the lottery .

 

[Captain Kilowatt]

Get something up that has some vertical component to it.As Doc said an inverted L will work OK. I am using an inverted L that has the vertical portion about 33 feet high and the horizontal portion about 70 feet long.It is fed with coax and a 4:1 matching transformer which is not really necessary but I was experimenting and left it in to raise the feedpoint impedance to provide a better match to the 50 ohm coax feeder.It is grounded against the tower base at the bottom and is about five feet from the tower at the top.On 80m it hears better than my 300 foot longwire in most cases and on 160m it is usually better than the longwire.It works really well on 17m too which was a surprise.

 

[CDX-007]

Rule of thumb: vertical, or horizontal IF erected near 1/2 wavelength above ground, for DXing, ie: Europe, Asia, Australia, etc...,
-OR-
horizontal close to ground for NVIS (Near Vertical Incident Skywave) for contacts relatively nearby, for example (if located in Fresno, Ca) - West coast - Western US, Hawaii, Alaska...

160m is a tough one with it's ~125' 1/4 wavelength. so I'm going to try a 'Slinky' antenna configured as a 75m-length Inverted Vee (50' apex) as I only have room for a 75m length Vee.

It will be 450 ohm ladder-line fed from a Dentron tuner which performs nicely right now at 60'/side on 75m but SUCKS on 160m.

Currently, like you, if I want to be heard on 160m I have to short together both leads of my 450ohm and treat it like an end fed long wire on the rear of the tuner. (450ohm works better than coax for this)

I'll report on the performance of the Slinky asap as you also have room for a 75m Inv Vee.

 

[Captain Kilowatt]

Rule of thumb: vertical, or horizontal IF erected near 1/2 wavelength above ground, for DXing, ie: Europe, Asia, Australia, etc...,
-OR-
horizontal close to ground for NVIS (Near Vertical Incident Skywave) for contacts relatively nearby, for example (if located in Fresno, Ca) - West coast - Western US, Hawaii, Alaska...

160m is a tough one with it's ~125' 1/4 wavelength. so I'm going to try a 'Slinky' antenna configured as a 75m-length Inverted Vee (50' apex) as I only have room for a 75m length Vee.

It will be 450 ohm ladder-line fed from a Dentron tuner which performs nicely right now at 60'/side on 75m but SUCKS on 160m.

Currently, like you, if I want to be heard on 160m I have to short together both leads of my 450ohm and treat it like an end fed long wire on the rear of the tuner. (450ohm works better than coax for this)

I'll report on the performance of the Slinky asap as you also have room for a 75m Inv Vee.

Actually rule of thumb for the low bands,80m and 160m is if you want true DX then VERTICAL is the only way to go even if it is a ground mounted antenna.It has nothing to do with height above ground as a ground mounted vertical antenna with radials will have a much lower take off angle than even a horizontal dipole at 1/2 wavelength or better.

Also when you short the ends of your 450 ohm line together it does not act like an endfed long wire.It acts as a top loaded vertical antenna.The feedline does the radiating and the antenna does the top loading.Since both halves of it are out of phase the horizontal radiation is cancelled out leaving you with a vertical radiator.

 

[CDX-007]

Actually rule of thumb for the low bands,80m and 160m is if you want true DX then VERTICAL is the only way to go even if it is a ground mounted antenna.It has nothing to do with height above ground as a ground mounted vertical antenna with radials will have a much lower take off angle than even a horizontal dipole at 1/2 wavelength or better.

...and there's varying schools of thought regarding the first bounce preferring horizontal over vertical even on the low bands. Loops do quite well and tend to have a fairly low angle horizontal polarization.

Also when you short the ends of your 450 ohm line together it does not act like an endfed long wire.It acts as a top loaded vertical antenna.The feedline does the radiating and the antenna does the top loading.Since both halves of it are out of phase the horizontal radiation is cancelled out leaving you with a vertical radiator.

I believe I wrote "...treat it as an end fed long wire on the rear of the tuner", but as it's an inverted Vee, NOT a flat top dipole, the coupling from the two opposing ends seems to act more like a capacitance hat at lower than resonant freq.s, and is noticably better on 160m than was my 95' sloper, and seems to TX better when I use BOTH halves of the Vee rather than only one side like an inverted L.

73

 

[Captain Kilowatt]

Ooops! I misunderstood what you meant.I guess you meant that you would treat the feeders that are tied together as if it were an endfed wire as far as HOW to attach it to your tuner? Also,either way the dipole or inverted vee will still add capacitive top loading to the radiator which is actually the feedline.The two halves are still out of phase and will cancel out the radiation from it. I have a 300 foot long wire antenna that slopes from 40 feet down to about 10 feet at the far end and in almost all cases my inverted L which is 33 feet vertical and 70 feet horizontal beats it and that is without any radials at the feedpoint.Sometimes the inverted L picks up a bit more noise but in almost all cases the signal strength is stronger on the L. I have noted stronger signals on the L when listening to the AM broadcast band where the signals are all vertical as well as throughout the lower HF bands where the polarity is anyones guess.The longwire will perform better on some AM broadcast stations depending where they are and if it is skywave or not but it ALWAYS performs better on the international longwave broadcast band.No substitute for size on 200KHz.I wish I had the room for the 660 foot longwire antenna I had when I was still living at my parents place.I had five and a half acres to play with and lots of trees. Boy did I pick up a lot of broadcast stations on LW and MW from around the world.

 

[Moleculo]

I understand that the inverted V with shorted ladder line looks like a top loaded vertical, but what does my shorted 80m loop look like? There's not a lot of feedline up until the loop starts (about 12').

 

[Captain Kilowatt]

A 12 foot vertical with a really,really big capacitance hat? :?

 

[Moleculo]

heheh.....that's what I thought too but I had to ask. It seems kinda funny when you think about it. I wonder if I broke the loop in the middle if it would look more like parallel long wires?

 

[CDX-007]

I understand that the inverted V with shorted ladder line looks like a top loaded vertical, but what does my shorted 80m loop look like? There's not a lot of feedline up until the loop starts (about 12').

Is the feedline 50ohm? What's the length of the wire making up your loop, Moleculo?

 

[jonbah]

If you have a tower this one will work.

limited space 160



Jonbah

 

[Moleculo]

The feedline is 450 ohm ladder line. The loop is a full wave 80m...approx. 250 ft of wire.