My Beverage antenna is NOISY! Why?

[cottersay]

I built a single wire 40Meter Beverage pointed towards the N.E., 1.3 wavelengths long and 10 feet high (above "antler height"), and it is far noisier than my full length 40M dipole that is up 50 feet.

I just can't figure out why; I am using a DX Engineering matching transformer that is grounded with four ground rods and two long radials running at 45 degrees off from the antenna itself, while the end of the Beverage is terminated in 470 ohms and attached to two ground rods. I even tested the antenna, and it has an SWR that is not over 2:1 between 6MHz and 16MHz. Further, the (75 ohm) coax is buried for much of its run.

What would contribute to a Beverage being so high in noise over that of a simple dipole (which receives signals quite well in both amplitude and S/N)?

73,

-Cotter

 

[cottersay]

Why is my Beverage so noisy?

[I posted this yesterday, but it apparently didn't "take"]

I was wondering if you guys had any ideas: I built a single wire 40Meter Beverage pointed towards the N.E. that is 1.3 wavelengths long and 10 feet high (above "antler height"), and it is far noisier than my full length 40M TX dipole that is up 50 feet.

I just can't figure out why; I am using a DX Engineering matching transformer that is grounded with four ground rods and two long radials running at 45 degrees off from the antenna itself, while the end of the Beverage is terminated in 470 ohms and attached to two ground rods. I even tested the antenna, and it has an SWR that is not over 2:1 between 6MHz and 16MHz. Further, the (75 ohm) coax is buried for much of its run.

What could contribute to a Beverage being so high in noise over that of my basic dipole (which receives signals quite well in both amplitude and S/N)?


Many Thanks!


-Cotter
..............................................................................................NORTH..........................................................................................

 

[rivardj]

The drawing looks like the beverage antenna is pointed directly at your house/shack. How many computers, florescent lights, televisions and other electronic devices are running in your house that may be causing interference?

 

[cottersay]

I need my RX Beverage to point in the same direction as my TX dipole antenna (Europe). But do you feel that the radiation pattern at the terminated end of a Beverage is so that the main lobe is receiving QRN from my house? If so, I will have to move the Beverage to point further north -- not optimal, but it is better than this high noise floor I'm receiving!!

Thanks,

-Cotter

 

[RBMTS]

Try shutting off as many AC panel breakers for the house that you can (including the pool filtering equipment). If possible, leave only your shack powered. See if your noise level drops. If it does, turn breakers back on one at a time so that you can see if a particular circuit brings the noise back.

 

[mikewazowski]

[I posted this yesterday, but it apparently didn't "take"]

No, it took. You just didn't wait long enough for a Moderator to approve your post. As a new member, you must have a minimum number of posts approved by a Moderator before you're given regular posting privileges.

 

[rivardj]

I need my RX Beverage to point in the same direction as my TX dipole antenna (Europe). But do you feel that the radiation pattern at the terminated end of a Beverage is so that the main lobe is receiving QRN from my house? If so, I will have to move the Beverage to point further north -- not optimal, but it is better than this high noise floor I'm receiving!!

Thanks,

-Cotter

That is my guess.

 

[Boombox]

Like Rivardj said -- looks like that beverage is aimed right at your house.

Means it's going to pick up RFI from that direction.

From what I've read, beverages' strengths aren't that they are low noise antennas (like a loop is supposed to be) -- they're primarily high gain receive antennas from the direction of the main lobe. Which would explain why you're hearing the noise.

And I don't have my antenna handbook handy, but 1.3 wavelengths might not be long enough to have an extremely narrow lobe -- which would explain why it may be picking up RFI from your house.

 

[majoco]

...and you have the high impedance end of the antenna right where it will pick up the maximum noise from your house.

 

[cottersay]

Thanks guys; in fact, I'm in the midst of not only lengthening the Beverage by another 75', but it is now going to go past the N.W. corner of the house (sadly for the XYL, the end pole will now land directly in the front yard, but she's understanding -- sort of).
I really hope this does the trick!

 

[cottersay]

Modified my Beverage as per Radio Reference tips

Hi Y'all,

I just modified my Beverage antenna as per your guy's tips 'n tricks. Here are the results.

After days of work I built a new Beverage that was not only longer (280' total length), but also does not point towards my house anymore (1st Picture Below).

And as you can see, we live in a non-urban area (2nd Picture Below).

​My plain old full length 20/40M fan dipole 40M output (3rd Picture Below).

My new Beverage signals on 40 meters. The LNA for the Beverage is bypassed. (4th Picture Below)
​​
I have no idea what I could be doing wrong, but I think that the great Radio Gods are not smiling on my attempt at constructing Beverage antennas...

Any thoughts?

-Cotter

 

[Boombox]

I'm no ham or expert -- on antennas in general or beverage antennas in particular -- but that antenna is possibly still pointed just too close to your house. Like other wave type antennas, beverages have lobes, and it's possible one of the lobes is pointed at your house. It also appears that it is pointing at another house a block away, which could have RFI generators inside (and maybe the other nearby houses too).

My neighbor's plasma TV plastered 40 meters for over a year (til they got a different TV) and another neighbor's wash machine (over a block away) puts weird noises all over the HF from below 49 meters to above 41 meters. In that case it was using the above ground powerlines as an 'antenna'. Nearly ruined my listening hobby. I feel your pain.

 

[cottersay]

Thanks Boombox, I figured the same thing. All it takes is one bad apple (on the block) to spoil a ham's fun! And since I want to QSO with Europe there is no way I can move the Bev further away from my house, or to point it in a different direction (plus, I'm out of room as it is). If things don't get better on the Bev soon, I may go with a phased twin vertical array (since I have the parts to do it). Dang it!

Thanks,

-Cotter

 

[Boombox]

Have you considered a large 40 m quad loop? You'd get more gain than you'd get from your dipole, and possibly a bit less noise. You'd still have some RFI issues (if there is RFI coming from the house, other houses, etc.).

But it's possible you could orient the loop (by angling it away from the house but still towards Europe) in a way to reduce the reception of RFI from your house and still maximize what you hear from the NE. Or you could alter the direction of your dipole slightly and reduce the RFI that way, and still talk to Europe.

Or, try moving the Beverage from the direction it's pointed now, to a different direction, more along your fenceline. It might reduce the reception of the RFI enough to still hear / talk to the NE. If you check out the antenna patterns online (half wave, quarter wave, full wave, wavelength and a half, etc.) you can see the orientation of the main lobes and that may help you still get use out of a Beverage.

Another idea is to angle the orientation of your dipole and add a wire director. I did that once on sideband CB and was able to talk to Mexico and Texas from my location in the Pacific NW.

 

[cottersay]

Thanks Boombox. Some great suggestions. However, after a lot of rain and time here, my guess is that the Beverage ground rods (of which I have MANY!) have had more of a chance to become in more intimate contact with the earth now, because all of a sudden my Bev is starting to win in the battle for the best SNR with the dipole (even on 20M)! Indeed, I have read about this "settling in" needed for new ground rods, especially after being driven into the ground by an inexperienced "steel drivin' man"; the vibrations caused by the off center hits of the sledge against the top of the rod causes the earth -- even deep down -- to be pushed away and separated from the rods due to excess vibrations. (That is why after some people (like me) who have driven the rods down deep into the earth, can then grab the top end of one and actually physically shake it back and forth. That is bad; the rod should be almost immovable. However, time and rain should -- and apparently is -- fixing this issue).

You have my rapt interest; what is a "dipole with a wire director"?? Sounds fascinating.

 

[Boombox]

A dipole with a wire director is similar to a two element yagi in principle: you just hang a wire a given distance in front of the dipole (I can't remember the formula offhand, but it would be the distance between a driven element and the first director on a yagi), making sure it is cut to a given length (a certain percentage shorter than the dipole). It adds some gain in the direction of the director.

I can't recall how much gain it added but it was worth the trouble.

I made one of these years ago. Worked really well, before it blew down. Everything was suspended by ropes.

 

[NDRADIONUT]

How about starting your bev. From the term. Point and run it ne away from your house ??

 

[cottersay]

I may not understand your question, but if it is what I think it is it's because the term point is near the edge of my property. I had to shoe-horn the 280' Bev as it is.

 

[cottersay]

Ah yes, thanks Boombox, I am familiar with that antenna. I use to call it a "wire Yagi". Always wanted to build one, but it never worked out due to incorrect tree spacing and/or height. The problem here is height; that while I have enough trees, they do not reach the height of my present simple dipole.

 

[NDRADIONUT]

Ok i thought you had more to work with... Folded multi band dipoles with a 12:1 balun and 600 ohm term. Resister are pretty quiet....