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Technical Topics => Equipment => Topic started by: ChrisSmolinski on September 08, 2014, 1338 UTC

Title: I finally put up a Beverage antenna
Post by: ChrisSmolinski on September 08, 2014, 1338 UTC
While I've been getting fairly good results with my sloping folded dipole antenna for listening to Europirates, I wanted something with a bit more directionality.

I've known about Beverage antennas for decades, but never used one. I did some reading online about them, I will say, there is a lot of contradictory information.

In a nutshell, a Beverage antenna is a long wire antenna, terminated at the far end. Some authors say you should slope the wire down to the ground at each end, others say to keep it at a constant height, then use a vertical piece of wire at each end. Half say that the wire should be something lossy like electric fence wire, the others say to use coper wire. You want to install it over a poor ground, except for the authors that say you want a good ground. The value of the terminating resistor is critical, except when it isn't. And everyone has a different opinion over how long it should be. You get the idea, the usual situation with ham radio antennas.

I decided that putting up something would be better than procrastinating while sorting out all the details, so I looked around to see what materials I had. I found some antenna wire, but no pieces long enough for the entire run, so I ended up splicing together 4 pieces of different wire.  I had a path in the yard that was a little over 200 ft long in the correct direction. Going further would mean hacking a path through brush and possibly poison ivy, so I decided that would be long enough for now. It's 1.25 wavelengths long for the 48 meter band, which according to much of what I read should be long enough for reasonable directionality.   The bearing is 50 degrees, which according to a great circle map is what I want to hit Europe (or more precisely get hit by radio waves from Europe).

I bought a pair of 8 ft ground rods and clamps for each end of the antenna. I was dreading pounding them into the ground. Some online reading brought up an interesting suggestion. Fill a soda bottle with water. Push the ground rod into the ground. Then drizzle water down the rod so it goes into the ground. Push the rod some more. Lather, rinse, repeat. Guess what? It works! I was able to get each rod most of the way into the ground this way. I eventually hit some rocks, making hammering necessary, but it was much easier than I thought it would be.

I decided to keep the Beverage roughly uniform in height the entire length, then drop a wire vertically at each end. The antenna runs in a section of the yard with some trees, so I support it with rope attached to branches every so often. It is not completely level, but hopefully close enough.

The far end of the Beverage has a termination resistor. Supposedly the ideal method is to use a SWR meter, transmit at low power, and vary the termination resistance until you have a uniformly high (flat) SWR over all bands of interest. I decided to just go with a value of about 450 ohms, since I had some resistors to get to that value. From what I read, you do want to use power resistors (non inductive of course) since nearby lightning can induce current in the wire, burning out smaller resistors. I cobbled together some resistors in parallel to get to about 450 ohms.

Since the impedance of the Beverage is high (about 450 ohms) you want a matching transformer. I have quite a few cores in the junkbox, but of course no idea what composition any of them are. There's apparently an international law prohibiting marking ferrite and iron cores with a part number.  I selected what I thought was an appropriate core, wound  a transformer, and connected it to the antenna and some RG-6 coax (I use RG-6 now for all my antenna runs, because it is easy to find and inexpensive). While I got signals from the antenna, the performance was not really that good. Suspecting the problem was the transformer, I looked around some more, and found a balun, either 4:1 or 9:1. (While it was marked, the number had long since worn off)  I substituted that for the matching transformer, and voila! success.

In the afternoon, I was picking up audio from CBC on 6160 kHz. There was nothing at all on the sky loop, and occasionally a carrier would pop up with the dipole, but that was about it.  I did notice a lot of RFI pickup, then realized that because I was using the antenna with the SDR-14 (powered with an AC adapter) plugged into a laptop, the coax shield was not grounded. I grounded it in the shack, and the RFI went away. Further comparisons later in the evening, once some Europirates were coming in, showed better reception with the Beverage. The overall signal levels are lower, as expected, but the noise levels are much lower.

There's two potential things I can still do. First (and easiest) is the matching transformer, to see if something else will work better than the balun. Second (and much more work) is to hack a path through the brush to extend the Beverage out to about 2 wavelengths or more (which also would improve reception on lower frequencies).  But even without either of those changes,  I think I have an improved antenna for Europirate reception. And just in time for the Fall/Winter DX season.
Title: Re: I finally put up a Beverage antenna
Post by: Jari Finland on September 08, 2014, 1449 UTC
Hi! Good post. Please let me add a line or two about my experiences.

Some authors say you should slope the wire down to the ground at each end, others say to keep it at a constant height, then use a vertical piece of wire at each end.

Often in literature they recycle old plans without a bit of thinking. With luck the author who is writing about antennas has never even tried them. I have got an impression that the setup where there is a vertical piece of wire in the end to the resistor and grounding is more like an illustration of principle than a real schema. In practical situations I have often simply pulled the wire to the ground in an angle of 45 degrees or something close to that after the last branch of last available tree and I haven't even given a thought for that. In fact often I have even turned the end of wire around the tree two or three turns to make sure I am not losing the end of wire from my fingers. Of course this is strictly against all the principles, because now we have a coil in the end of wire, but in -20 C conditions some compromises might be allowed.  ;D

Quote
Half say that the wire should be something lossy like electric fence wire, the others say to use coper wire.

Warning: You don't want to use regular plastic coated wire in -30 C. The plastic frozes and peels away as soon as you are going to roll it. I have ruined some potentially pretty good wires this way. Thick flexible plastic coating or enamel is ok. (Dad, what they mean by extreme conditions?)

Quote
Fill a soda bottle with water. Push the ground rod into the ground. Then drizzle water down the rod so it goes into the ground. Push the rod some more. Lather, rinse, repeat. Guess what? It works!

Fantastic!

They also say that if conductivity of soil is low, one could apply a kilo or so salt into the hole. On the coast a metal wire fish trap in sea should do the same. My personal ultimate solution, that worked great for a while while listening to Indonesians on 90 metres was to hammer a copper nail into a big tree. After some time it stopped working well. I guess I should have pulled nail away and hammer it in a new fresher place. Copper nail doesn't harm trees too much.

Quote
Suspecting the problem was the transformer, I looked around some more, and found a balun, either 4:1 or 9:1. (While it was marked, the number had long since worn off)  I substituted that for the matching transformer, and voila! success.

I never had matching problems while using trad comm receivers. MW band is so wide that one can't really seriously match an antenna there anyway. The problems began, surprise surprise, immediately with Perseus. Even a portable Grundig brought better signal from Radio Merkurs than Perseus with 500 metres wire. Raw wire into plug didn't work at all and Perseus doesn't have any hi-Z input.

It was unexpectable to me. For the first time in my life I was using a receiver that absolutely requires matching. 9:1 turns over ferrite core with least loss on MW (I have the comparison chart here somewhere) did the thing.

One can also ponder, whether a termination and grounding is necessary. Case study: 50 degrees 600 m long wire to Japan. Excellent tool to listen to 1413 JOIF almost daily during winter time. I might ground it if I like, but then I would lose back beam, and the back beam of 50 degrees points almost exactly towards Netherlands and offers many MW dutches after dark. Back beam towards powerful Europeans does not matter while listening to Japanese, because at Japan listening time it is afternoon here, and most euros are in sunlight. Even in late evening, if conditions allow, dominant Far East stations like HLAZ and JOIF can boom at S9+dB over the weak euros on their frequencies.

NA beverage on the other hand, is a real terminated beverage. I don't want strong Russians to block weak American signals in morning. Terminated beverage doesn't magically wipe away the interference from opposite direction, but it helps, sometimes more, sometimes less.
Title: Re: I finally put up a Beverage antenna
Post by: Pigmeat on September 08, 2014, 1632 UTC
I used that water trick when driving metal fence posts as a teen. If it works in our sticky red dog clay, it will work anywhere. (Except on solid rock or Al Fansome's unusually round head.)

A lot of the terminated beverages you read about in antenna manuals and ham mags are for transmitting. The resistor wattages recommended can be pure overkill for listening.

Our man in Finland has some solid advice, listen to him.
Title: Re: I finally put up a Beverage antenna
Post by: Rafman on September 09, 2014, 2129 UTC
Chris,

If you want to make your own 9:1 Beverage transformers, have a good look at this page: http://www.w0btu.com/Beverage_antennas.html

The best way to make them is with BN73-202 Binocular toroids [Fair Rite 28730000202] which cost ~$0.25/ea

http://www.w0btu.com/Beverage_antennas.html#Beverage_Antenna_Transformers <--- gives you Primary/Secondary ratios from 1:1 to 16:1

You can also calculate all the values, including wire length, at http://toroids.info/BN-73-202.php

The boxes cost more than the transformers but I have an end cost under $20/ea

Here's how they look & I actually bought 100 cores back to years ago... Finally making the boxes means it's going to be a great listening season!  ;)

Hope this helps!

Rafman
Title: Re: I finally put up a Beverage antenna
Post by: ChrisSmolinski on September 11, 2014, 1920 UTC
Rafman,

Thanks for the info!

One question, have you found it important to keep the height of the beverage uniform over the entire length? Mine is made with stranded copper wire that is supported overhead from branches every so often, so there are several sags in it.
Title: Re: I finally put up a Beverage antenna
Post by: DimBulb on September 11, 2014, 1940 UTC
I don't think sags are a problem.

I have several books that contain sections describing these antennas including "The ARRL Antenna BooK", ON4UN's "Low Band DXing" and one source specific to beverages "The Beverage Antenna Handbook" by Victor A. Misek
Title: Re: I finally put up a Beverage antenna
Post by: Pigmeat on September 11, 2014, 2024 UTC
I've used beverages on the ground (BOG) for years at the farm. They work well and don't seem to pick up as much noise from the electric fences the local cattle farms use.

As for the poison ivy, when you're done hacking through it, dump your clothes in the washer, then immediately take a shower using dish washing liquid, which is a detergent. It will lift the urushiol, (the oil that causes the rash) off of your skin and send it down the drain where it belongs. Soap and water won't cut it with urushiol, they just spread it around your body.

BTW, never burn poison ivy and it's relatives. If the wind shifts and you inhale the smoke, you get to go to the hospital. If you're hypersensitive to the stuff and you inhale it, you could be dead before the ambulance gets there.
Title: Re: I finally put up a Beverage antenna
Post by: ChrisSmolinski on September 11, 2014, 2136 UTC
Pigmeat,

My general procedure with Poison Ivy is to spray heavily with Roundup, then wait a year :-)
Title: Re: I finally put up a Beverage antenna
Post by: Pigmeat on September 12, 2014, 0405 UTC
That's what I used to do, but my wife has gone all nature friendly.

Personally, I'm an Agent Orange man, but if I want clean underwear and cooked food, I've got to play along.
Title: Re: I finally put up a Beverage antenna
Post by: Rafman on September 12, 2014, 0526 UTC
Chris,

In my experience, it doesn't really matter & if it does, I never noticed it. When I ran the 2000'+, it was impossible to keep it flat since my property has several deep valleys on it. All I did was be sure to keep the minimum distance above ground at insulator locations. It wasn't even in a perfectly straight line either but it strolled when I could hear Morocco on 172KHz during late afternoon daylight!!!

Pigmeat,

You utter the words of a Wise Man. We all must make deals with the ummm "Angels" but the examples you cite lead me to a thought.
Perhaps these are the reasons Cave Men ate raw meat & wore Loin Cloths???  ;)

Rafman
Title: Re: I finally put up a Beverage antenna
Post by: zackers on September 16, 2014, 1519 UTC
Beverages are pretty amazing when installed properly. Several hams in this area use them on 160 in the winter. The farmers who own adjoining fields let them put the Beverages up in their fields. One ham uses as many as seven, aimed in different directions. In a contest a couple years ago I was hearing stations on the Beverages that I couldn't hear a peep from on a gamma-matched tower being used as a vertical on 160.
Title: Re: I finally put up a Beverage antenna
Post by: ChrisSmolinski on September 16, 2014, 1526 UTC
I've been using it the last two days on 11m (yeah, I know, a beverage on 11m??) to listen to UK CBers. And it's working very well. I'm hearing stuff that isn't even a trace on the other antennas.
Title: Re: I finally put up a Beverage antenna
Post by: Jari Finland on September 16, 2014, 1736 UTC
I'm not surprised at all. Best reception I have had with Irish church/parish radios on 27 MHz was with 500 metres long beverage as an antenna.
Title: Re: I finally put up a Beverage antenna
Post by: ChrisSmolinski on September 16, 2014, 1910 UTC
I'm not surprised at all. Best reception I have had with Irish church/parish radios on 27 MHz was with 500 metres long beverage as an antenna.

Good to hear! That is exactly what I am going to be doing with it this fall.
Title: Re: I finally put up a Beverage antenna
Post by: DimBulb on September 18, 2014, 2341 UTC
   Another well-known practitioner of beverage antennas is Charles Rauch, W8JI.  I don't think he's published a book like the other guys I mentioned but he does have some on-line info at:

   http://www.w8ji.com/beverages.htm

   Includes comments about some of the points you brought up...

   An interface designed by him is available at:

   http://www.dxengineering.com/parts/dxe-bfs-1
Title: Re: I finally put up a Beverage antenna
Post by: Rafman on September 19, 2014, 0115 UTC
I put a beverage up today & am I ever impressed!
It's amazingly quiet! Here is a quick check of results comparing:
~1 wavelength [for 6MHz or 150'L @9'H]beverage [TOP] Elad S1
vs
~Full Wave 7MHz loop [BOTTOM] Elad S2,
While listening to the same exact pescadores on 6925 LSB.
Granted the beverage is beaming to EU but just the noise floor difference is astoundingly quiet in comparison!!!
Title: Re: I finally put up a Beverage antenna
Post by: Pigmeat on September 19, 2014, 1207 UTC
The first time I used a BOG, Beverage On the Ground, it was so quiet I thought a static charge had taken out the front end of my receiver, lol.

Beverages shine come mid-summer when storm noise is rendering other antennas useless, IMO. They're not too shabby in winter either.
Title: Re: I finally put up a Beverage antenna
Post by: IQ_imbalance on September 30, 2014, 0439 UTC
Is anyone trying to match impedance, or just connecting direct to coax w/out?  I'm particularly interested in the BOG.....
Title: Re: I finally put up a Beverage antenna
Post by: Rafman on October 02, 2014, 1105 UTC
I wound my own 6.25:1 using a Binocular core...
That matches 450 ohms to 75 ohm coax...
Title: Re: I finally put up a Beverage antenna
Post by: RobRich on October 19, 2014, 0417 UTC
If you want to skip a transformer, try an unterminated BOG, which is actually little more than a longwire on the ground. The tradeoff without termination is it will actually be somewhat directional off both ends. Use a ground rod and/or a small radial field for the RF ground. Wind a 1:1 feedline isolator.

My previous HF antenna of choice was a slight variation of the above. I used 148' of RG-6 coax for the antenna element. The feed point went to center, with the antenna coax shield floating. At the far end, the center was terminated to the shield. RF ground was just a ground rod. It was not very directional, but it was rather quiet for noise. Naturally, a decent preamp is recommended, too.

Moving onto my current antenna-on-ground setup, I have an 148' "shielded" square loop placed right on the ground. I went for capture area due to the ridiculously high ground losses incurred. The loop is built with RG-6 coax. The center conductor forms the loop, with each center feed feeding a 1:1 current bulun. The shields are bonded together at the feedpoint side and tied to a ground rod, then broken at the symmetrical far side from the feedpoint. RG-6 for feed line, with multiple ferrites installed at random intervals.

The loop-on-ground is routinely used for longwave to mid-HF, usually without a preamp. There is a distinct falloff above ~10MHz, even with a preamp. I often use the loop even for listening to longwave broadcasters across the Atlantic, again without a preamp, which I think is decent considering my suburban location.
Title: Re: I finally put up a Beverage antenna
Post by: Antennae on November 01, 2014, 0025 UTC
I just put up a beverage about 140' long. Just long enough for one wavelength of 6.925mhz.  I have it aimed at Virginia. I figure its the middle of the East Coast and I'll catch stations on either side.   I haven't heard pirates with it yet.

 But there was Vatican Radio from Madagascar last night, on my horizontal loop it came in and the voices were garbled, there was some crackles, and there was noise.  But with the beverage, the voices were clear, and the crackles and noise went away!

With the loop I've become gain shy because the noise gets amplified too.  But with the beverage I can turn up the gain a bit before the noise raises much. 

I've got aligator clips connecting my portable to the beverage. I first connect the positive, then, when I connect the ground the noise goes way down. Its fun to make it vanish.
The ground goes from my roof down the wall into a ground rod. It picks up noise from some LED lights inside the house so I have to turn them off when listening. 
Title: Re: I finally put up a Beverage antenna
Post by: Antennae on November 01, 2014, 2112 UTC
I checked the beverage with an MFJ-259 antenna analyzer:
Frequency     SWR
1.8 - 4 mHz  1.5
4-7 mHz       1.5
7.6 mHz       1
10 mHz        2

After 10mHz, SWR up and down from 1 to 3

Title: Re: I finally put up a Beverage antenna
Post by: Rafman on November 01, 2014, 2139 UTC
Antennae,

What are you using for a transformer?
Termination resistor?
Ground rod at both ends?
How high is the element off the ground?

Just curious... I'll wave at you since it is pointed right at me  :P

Rafman
Title: Re: I finally put up a Beverage antenna
Post by: Antennae on November 02, 2014, 1857 UTC
I bought a DX engineering beverage antenna kit. DXE-BFS-1

9:1 transformer
470ohm termination resistor
8' terminating ground rod, galvanized 1/2" conduit
9.5' ground rod, same conduit
Element varies 10'-8' above ground.
18 or 20 gauge copper strand element wire

It helped out on some stations Haloween night.

I think this makes my portable receiver the weak point in my system. There was some faint USB stuff the other night and if something was just a little better it would have helped out.
Title: Re: I finally put up a Beverage antenna
Post by: Rafman on November 03, 2014, 2349 UTC
Yes, I would get a substitute receiver, to replace the portable.

My suggestion, an SDR of course  ;)

I just surveyed for a 2nd beverage [S-SW] & an EWE [W-NW]...

Then it will be time to finish my LZ1AQ Active Loop... I'll be finished just before the snow falls [hopefully]

Good Job Antennae!!!

Regards,
Rafman
Title: Re: I finally put up a Beverage antenna
Post by: Jari Finland on November 07, 2014, 1427 UTC
Meanwhile in Aihkiniemi...

http://areena.yle.fi/tv/2211035?start=10m59s (http://areena.yle.fi/tv/2211035?start=10m59s)

For purposes of exotic it is a Sami language tv news with Finnish subtitles.  ;D
Title: Re: I finally put up a Beverage antenna
Post by: RobRich on November 08, 2014, 0054 UTC
You probably can forget the antenna analyzer due to the 9:1 balun and the ground losses involved. I suspect it wil show a decent impedence match across much of the HF spectrum.

Since you are running a terminated beverage, if possible, try increasing the length to gain directivity off the terminated end. Beverages are often at multiples of desired wavelengths. Your beverage easily could be like -30dB (or lower) from an isotropic. You either need more antenna gain and/or possibly a preamp to offset the difference. You can build a basic HF preamp for a few dollars, or perhaps even consider a combined preselector/preamp unit from MFJ or similar.
Title: Re: I finally put up a Beverage antenna
Post by: Jari Finland on November 08, 2014, 1516 UTC
You either need more antenna gain and/or possibly a preamp to offset the difference.

Some thoughts after sauna and during hockey game (Finland-Russia, 2-2, 2nd period)

Preselector was used routinely and extremely successfully with beverages until large bandwith recording with sdr made it obsolete. A good quality (pay attention to S/N ratio) large bandwith preamp is nowadays the replacement. In places where signal strengths are abyssmal, like in Lapland, they sometimes use three preamps in series! It's an ultimate solution and I wouldn't dare recommend it in surroundings where MW stations are actually operating.

Another thing that started ticking in the back of my mind was what Chris said, that he tried to draw the wire vertically as tight as possible. Probably the variety in vertical height doesn't matter at all. If the wire runs over branches at 3 metres, those looser periods where wire hangs on 1 metres or even lower, are meaningless in big picture. I have never found much difference in it, if any. Beverage is, after all, a vertical polarized antenna. (Believe it or not.) If wire goes at some place down to the ground, for sure that doesn't look good and I'd like to avoid that, but fortunately frozen earth is a miserable conductor.

Whee, 5-2.
Title: Re: I finally put up a Beverage antenna
Post by: Antennae on November 08, 2014, 1911 UTC
Thanks for the tips. I have a preamp by Palomar Engineers. When hooked up today, it was a little better than my built-in gain knob. It gave more middle range audio.
I was playing with it this morning.
11770 Voice of Nigeria    A faint female voice.
11735 Zanzibar Broadcasting Station  A male voice.
With both of these, I again feel I've met the limits of my receiver.  This is a cool antenna, too bad it needs length.  Right now I can extend it another 30 feet.
The longest line I can get would be pointed at Europe which would be fun to try. I don't have coax that long.
Title: Re: I finally put up a Beverage antenna
Post by: ChrisSmolinski on November 08, 2014, 1922 UTC
Right now my beverage is about 200 ft (62 meters) long. I primarily use it for 48 meter band Europirates.  I can extend it if I hack a path into the woods. Would adding another say 100 ft help significantly? Enough to make it worthwhile, that is, as it would be a bit of an effort.
Title: Re: I finally put up a Beverage antenna
Post by: Jari Finland on November 08, 2014, 1933 UTC
I'd say around 100 metres would be where beverage starts working (on MW). Before that it is a bit toy. :P
If it is possible, 200 metres is much better of course, and there is no limit...
Title: Re: I finally put up a Beverage antenna
Post by: ChrisSmolinski on November 08, 2014, 1946 UTC
I'd say around 100 metres would be where beverage starts working (on MW). Before that it is a bit toy. :P
If it is possible, 200 metres is much better of course, and there is no limit...

My primary band of interest is 48 meters, not MW. So I am wondering if it is already long enough, and I've reached the point of diminishing returns.
Title: Re: I finally put up a Beverage antenna
Post by: Rafman on November 08, 2014, 2003 UTC
Chris, is it 1 wavelength [~150']???

I would try adding resistance. I am using a 470 ohm & am about to add another 500 ohm pot to see if I can find a "sweet spot"...

Since you are targeting a region, adding another 150' [2 WL long], would narrow the lobe & increase forward gain...

My 1 WL exhibits good forward direction, on 49mb...  Try peaking your termination value... IMHO

Title: Re: I finally put up a Beverage antenna
Post by: ChrisSmolinski on November 08, 2014, 2025 UTC
It's about 1.3 wavelengths long now. So another 100 feet or so would take it to 2 wavelengths.  It will be a bit of a project cutting a path through the brush to do that, which is why I am asking around before I start :-)

I can try tweaking the termination resistance, maybe early this next week before the cold blast arrives.
Title: Re: I finally put up a Beverage antenna
Post by: Jari Finland on November 08, 2014, 2224 UTC
For what it's worth...

Even in the case I modeled long wire wrong (hey, everything is possible) I'd seriously consider using termination resistor to avoid antenna working as a backbeam. Look the front/back ratio.

Chris might be interested in comparing 60 m and 100 m behaviour on 6.3 MHz. It looks like a real choice would be 110 m (360 feet).

Needless to say, but take this only as an approximation.

Long wire for 6.3 MHz on 3 m height

               Gain dBi F/B dB angle Z=R+jX

50 m perfect ground   8.71   -0.02   62°   53-1021
50 m my real ground   10.46   0.52   57.6°   53-1021
60 m perfect      2.26   0.08   33.7°   15+250
60 m real         8.73   -4.96   31.0°   15+250
70 m perfect      6.31   -0.01   47°   2624+6214
70 m real         9.15   -0.34   44°   2624+6214
80 m perfect      3.38   0.04   53.8°   17-21
80 m real         8.07   -2.94   28°   17-21
90 m perfect      7.6   0.07   37.7°   36+982
90 m real         12.65   -1.71   32°   36+982
100 m perfect      7.28   -0.07   45°   23-414
100 m real         11.52   1.13   33.7°   23-414
110 m perfect      3.03   0.06   29.9°   24+447
110 m real         10.86   -2.89   26°   24+447
150 m perfect      4.9   -0.15   38°   18-130
150 m real         12.04   -0.72   22°   18-130
200 m perfect      1.79   -0.38   35°   19+65
200 m real         13.03   -1.31   19°   19+65
300 m perfect      0.39   -0.1   37°   43+431
300 m real         13.58   -1.09   17°   43+431
400 m perfect      1.05   -0.02   34°   271+1232
400 m real         13.32   --   14.5°   271+1232
500 m perfect      0.62   -0.05   31°   1079-1693
500 m real         14.09   1.09   13.5°   1079-1693

(modeling and "perfect ground" as figured by MMANA-Gal Basic)

My hunch is that there is something wrong here in this table, but... maybe I ponder the case later.

I started playing with MMANA-Gal because I wanted to design a perfect multiband wire antenna for ham purposes, which are completely different thing than listening purposes, and I almost think I found a solution with the magical length of 84 metres. But I haven't tested that in real life yet...
Title: Re: I finally put up a Beverage antenna
Post by: RobRich on November 09, 2014, 0039 UTC
Adding another 100' is not likely to offer a dramatic return IMO. If you could add a few hundred more feet, then I would say go for it.

I am with Rafman. Optimize what you have. Tweak the termination resistance. How is the feedline isolation? Consider winding a 1:1 choke out of the feeline at the feed point transformer. Install multiple ferrite chokes at random interval along the feedline. Each dB you can drop in locally coupled noise is hopefully another dB you can add to the S/N ratio.
Title: Re: I finally put up a Beverage antenna
Post by: ChrisSmolinski on November 10, 2014, 2037 UTC
I tried to adjust the termination resistance today, without success.

I used SdrDx on a laptop outside, via WiFi, so I could sit next to the termination point while adjusting it. I used a 1K potentiometer, not multi turn, so I don't think it was inductive. I first tried using WWCR on 31 meters, as it was pretty much in the backend of my desired pattern. I don't think I was able to get a null, but it was difficult to tell, due to fading. I then tried a MW station, which had a constant signal, but I could not get any sort of a null. Perhaps because the antenna is too short to be directional down there. (930 kHz station, the antenna is 200 ft long)
Title: Re: I finally put up a Beverage antenna
Post by: RobRich on November 11, 2014, 2118 UTC
Your 200' beverage will be practically almost omnidirectional at MW, and probably similar up through much of the tropical HF bands.

To tweak resistance tuning, instead try to find a decently stable station at a HF frequency where your antenna is multiples of the wavelength, thus allowing you to better assess the directivity and null(s).

BTW, did you ever determine if the transformer you are using is 4:1, 9:1, etc.? Balun or unun? A balun might have better isolation, but an unun is typically more appropriate for a traditional beverage. Try it both ways, though if going with an unun, you will probably want at least stacked/looped ferrites on the feedline to help with antenna RF isolation.