New antenna set up

nickcarr · #1 (**permalink**) 09-05-2009, 05:35 PM

So, I decided to move around my antenna today. It was roughly 300ft of Flexweave 14ga wire in multiple L shapes in the backyard. It was mostly flat (as in on-plane) but it had a few zags I didn't like. Height varied between 8ft and 25ft depending on the zag.

With the help of a trusty hammer and a few friends, we managed to "launch" the wire approximately 50ft into a tall tree that dominates the backyard.

(I did this several years ago with just 14ga copper wire but in time, the wire degrades and performance suffers; however, it was probably my best antenna ever.)

My set up isn't completely finished but right now. I'm using just 100ft of wire up over the tree. It's about 60ft on the long end at a 40 deg angle. The short end is about 60 deg angle. The best part is that it's about 25ft above the house. I'm hoping for a better DX angle.

This is all plugged into my DX 9:1 balun which is shorted to a copper ground rod (i.e. an Un-Un)

After analysis the results were about what I expected although I didn't expect a nice flat SWR reading across the 1.8 - 30mhz range. It starts at 2.0 and gets up to 3.7 but with a few dips to 1.2 in about 4 spots. (Believe it or not, this is relatively "flat" for this wide of HF range.)

I'm going to do a full plot tonight but tomorrow (weather permitting) I plan to add the additional 200ft. This will outline the backyard fence which will keep it flat (on-plane) and away from the house.

Now, the interesting idea that I have is to make this a full loop. (So, I would be hooking up the end to the balun, instead of shorting it.)

I will have to see how this all plays out, but this would be a very interesting set up to analyze afterwards.

Has anyone tried a large, rectangular loop antenna? I'm just curious as to what kind of results to expect.

ka3jjz · #2 (**permalink**) 09-05-2009, 08:13 PM

Nick, I know Lindsay was using a SkyLoop, but in what configuration it was, I don't know.

Just from some light reading, it seems that nearly circular or square SkyLoops are supposed to work better than triangles because of the greater area; I'm seriously envious of anyone that can put one of those up.

73 Mike

nickcarr · #3 (**permalink**) 09-06-2009, 12:49 AM

Ah, that was the name. Yeah I heard "skyloop" before but I couldn't recall the specific term.

I'll have to see how much wire I have left over but I think the loop should be do-able. It'll just depend on how I lay it out. I wish I could get the additional 200ft higher than 6ft. I'm not too concerned since this part will be far from any houses (a good 50ft on either side) so it should be a fairly quiet segment.

I've been doing some listening tonight and I'm amazed at how much of a difference in reception I'm getting. In general, I would say the bands are pretty sub-par but my reception has picked up quite a bit. I'm hearing a lot more broadcast stations now than I did before.

Obviously it would seem that height and angle are everything in terms of reception. Even a short antenna wire that is positioned just right can create excellent results.

It doesn't appear the weather will be helpful tomorrow. I'll try to get the loop up on Monday.

nickcarr · #4 (**permalink**) 09-09-2009, 04:06 PM

So I put up the additional section of wire that outlines my backyard fence. This was only about 100ft so I have some wire left over.

I analyzed the results and the one thing worth noting (from previous measurements as well) was that any time you "add" wire (so make the antenna lead longer electrically) my SWR came down to sub 2 levels. An analogy I thought up was the SWR plot is like a piece of wire being stretch out. Thus, the readings all drop across an even greater range.

The good news is that my antenna SWR is under 2 from 5mhz to 29mhz - this is using a 9:1 balun (in un-un mode.)

In terms of "hearing" all of my strong signals jumped about +10db. So, WWVH at 15mhz comes in at S9+40 instead of 30... (at it's peak propogation time.)

The only other observation was that the added length does seem to make the wire that much more sensitive to EMI. There are far more krackles and pops than with only ~100ft. I wonder if this is the case with really long lengths of wire (i.e. from a beverage antenna)...?

Next step will be to hook up the end of this lead to the balun and remove the short. This will make it a "balanced" antenna but I'm curious how this will affect my readings.

I'll update this again later this weekend.

PS. I'm thinking of adding a 2nd wire antenna using my 12:1 balun. Try to make this go in the opposite direction as my other antenna.

ab3a · #5 (**permalink**) 09-15-2009, 01:54 PM

Quote:

Originally Posted by nickcarr

I analyzed the results and the one thing worth noting (from previous measurements as well) was that any time you "add" wire (so make the antenna lead longer electrically) my SWR came down to sub 2 levels. An analogy I thought up was the SWR plot is like a piece of wire being stretch out. Thus, the readings all drop across an even greater range.

The good news is that my antenna SWR is under 2 from 5mhz to 29mhz - this is using a 9:1 balun (in un-un mode.)

You've probably heard others say it, but I'm going to repeat this mantra anyway. A good match doesn't mean the antenna is any good. Your UnUn could be absorbing a lot of the energy, so be careful how much power you put in to it.

Quote:

Originally Posted by nickcarr

The only other observation was that the added length does seem to make the wire that much more sensitive to EMI. There are far more krackles and pops than with only ~100ft. I wonder if this is the case with really long lengths of wire (i.e. from a beverage antenna)...?

A beverage antenna is not just a long wire. See Beverage Antenna Construction

In reality, it's more like an end-fire transmission line, several wavelengths long.

A beverage antenna is actually very lossy, so it's no good for transmitting. However, it is quite directional and it doesn't pick up much noise. If you happen to have a farm with a long fence line pointing in the general direction you want to receive, it may be a very good antenna for you.

k9rzz · #6 (**permalink**) 09-15-2009, 04:22 PM

For one Field Day operation, our group put up as much wire as the rules would allow - 500 ft, center fed with open wire feeders. We worked lots of stations but more importantly as some thunderstorms approached this monster antenna picked up the energy like nothing I have ever experienced. That code key was shocking me left and right until we just had to shut down. So, more wire _may_ mean more noise. It depends.

nickcarr · #7 (**permalink**) 09-16-2009, 04:06 PM

Quote:

Originally Posted by ab3a

You've probably heard others say it, but I'm going to repeat this mantra anyway. A good match doesn't mean the antenna is any good. Your UnUn could be absorbing a lot of the energy, so be careful how much power you put in to it.

Yes I'm aware of this... that's why I have an analyzer.

Nope, no room for a beverage here.

nickcarr · #8 (**permalink**) 09-16-2009, 04:13 PM

Quote:

Originally Posted by k9rzz

For one Field Day operation, our group put up as much wire as the rules would allow - 500 ft, center fed with open wire feeders. We worked lots of stations but more importantly as some thunderstorms approached this monster antenna picked up the energy like nothing I have ever experienced. That code key was shocking me left and right until we just had to shut down. So, more wire _may_ mean more noise. It depends.

Yeah I'm sure increasing the wire increases the wire's ability to pick up static electricity (from a thunderstorm for example.)

k9rzz · #9 (**permalink**) 09-16-2009, 05:02 PM

<Old timer speaking now> WHen I first got my novice license in 1976 (see!) I had an antenna tuner with the coil wound on a cardboard oatmeal container. One summer day, with storms approaching, I heard 'snap - snap - snap' and smelled something burning. My antenna was picking up static and discharging it somehow through the coil and the sparks were trying to start the cardboard on fire! </old>

Tip: Disconnect and ground wires when not in use.

ab3a · #10 (**permalink**) 09-17-2009, 11:18 AM

(Older Timer Speaking Now) I first got my novice license in 1975 ;-)

I once lofted a long, random wire antenna with a kite from a friend's yacht on the Chesapeake Bay. It was a beautiful clear summer day with a nice breeze. We were using Kynar insulated wire-wrapping wire (at the time we didn't know about the losses from small wire gauges). With about 200' of wire in the air, one of the guys grabbed it to attach to an automatic antenna tuner. He got the static shock of his life. It threw him across the deck and he nearly went overboard.

The static charge can happen at any time. It would be wise to ground the antenna with an RF choke or a high value resistor, so as to bleed off any static charge buildup.

raisindot · #11 (**permalink**) 09-17-2009, 12:42 PM

Quote:

Originally Posted by k9rzz

For one Field Day operation, our group put up as much wire as the rules would allow - 500 ft, center fed with open wire feeders. We worked lots of stations but more importantly as some thunderstorms approached this monster antenna picked up the energy like nothing I have ever experienced. That code key was shocking me left and right until we just had to shut down. So, more wire _may_ mean more noise. It depends.

I find it kind of funny that you kept at this after the FIRST shock. Were you perhaps channeling the spirit of Ben Franklin at the time?

Suzie