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Author Topic: Beverage for higher bands?  (Read 784 times)
KD0ZGW
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« on: December 07, 2017, 09:26:52 AM »

Given excellent Signal to Noise characteristics of a Beverage I wonder why I don't see references to using one on 20M.  Are there reasons why it's not used on higher bands besides the ability to make 20M beams with gain due to the smaller physical dimensions?

thx to anyone providing insight.

73's
KD0ZGW
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W1VT
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« Reply #1 on: December 07, 2017, 10:31:49 AM »

Assuming you could redesign it for the higher bands and keep the same pattern. Where would you put it to make use of its relatively high angle vertical pattern?  On 10M you really need a low angle antenna at this point in the Sunspot cycle to work DX.  Much easier to put up a tower than to find lots of steeply sloping ground to tilt the radiation angle down.  When I put up a Quad in Honolulu over steeply sloping ground I only needed a little bit of land.

The Waller Flag at 100 ft has a much lower radiation angle than a long Beverage on 160M.

Zack W1VT
« Last Edit: December 07, 2017, 10:34:15 AM by W1VT » Logged
K4SAV
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Posts: 2406




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« Reply #2 on: December 07, 2017, 04:39:08 PM »

Probably because of the practical limitations of constructing a Beverage for the higher bands and the fact that not many people have a need for Beverages on the higher bands.  Atmospheric noise is not very high on those bands.

You can do it but you have to also scale the height above ground.  Two feet above ground should be good for 20 meters.  If you make it higher, high angle lobes will develop.  For 20 meters a length somewhere close to 135 ft should work well.  You will need about 6 of those to cover 360 degrees with no more than 3 dB loss in S/N because of pointing error due to the narrow pattern.  Of course at 2 ft height, this will be an obstacle course of major proportions.

I don't have a Beverage at 2 ft height to test performance for various lengths.  EZNEC says longer wires also work (and work even better), but I don't trust EZNEC for very long wires close to the ground.  Experimental data shows that current in the wire disappears long before EZNEC says it does.

A BOG might be worth experimenting with.  I would guess that a length of about 40 to 60 ft might work.  Experimental data shows that attenuation on a wire 1 to 2 inches above the dirt goes up very rapidly with increasing frequency.  Gain is going to be very low.  Since I have tried it, I can tell you that a 250 ft BOG on 20 meters works poorly.

Jerry, K4SAV
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KD0ZGW
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« Reply #3 on: December 07, 2017, 07:02:46 PM »

Zack; thx for reply.  I do have some relatively steep slopes to work with long enough to get a full wavelength at 20M to the west and south.

Jerry; thx for reply and the explanation.  The 2' height is a deal breaker cuz my land is pretty much infested with deer so the wires wouldn't last very long.  Interesting idea though and I might lay one out just to see how it works but any experiments will wait until spring..

best regards;
KD0ZGW
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G8HQP
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« Reply #4 on: December 08, 2017, 04:54:24 AM »

Quote from: KD0ZGW
Given excellent Signal to Noise characteristics of a Beverage I wonder why I don't see references to using one on 20M.
I thought the Beverage was such an inefficient noisy antenna that it can only be used where external atmospheric noise swamps the antenna noise? OK for LF/MF reception where noise is high. Fairly useless for transmitting at any frequency, as most of the power heats the ground and the terminating resistor. Its main merit is simplicity.
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W1VT
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« Reply #5 on: December 08, 2017, 09:47:21 AM »

A low antenna may be shielded from noise sources by buildings while a high antenna would be line of sight to many noise sources. 
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K4SAV
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« Reply #6 on: December 08, 2017, 10:53:36 AM »

I thought the Beverage was such an inefficient noisy antenna that it can only be used where external atmospheric noise swamps the antenna noise?

Yes a Beverage is very inefficient but efficiency and gain is not a very important requirement for a receiving antenna.  The only noise generated by the antenna is due to the resistive loss of the wire and the termination resistor and that is usually below the noise floor of most receivers.  With low gain receiving antennas the noise floor of the system is usually limited by the preamp.  It's not difficult to design a preamp with noise less than the band noise on the low bands.  It's a little more difficult on the higher bands.

Jerry, K4SAV
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W1VT
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« Reply #7 on: December 08, 2017, 12:36:14 PM »

http://www.k7tjr.com/rx1comparison.htm
You can download EZNEC models of popular 160M receiving antennas and easily re-scale them to 20 meters.
Or just look at the pretty pattern plots if you don't know how to run this computer modeling program.
A 1000' Beverage scales to 132 feet, 1.32' high 20M antenna.  62 degree beamwidth with an elevation angle of 25 degrees.

About the same as a 3 element Yagi at 34 feet in terms of beamwidth and elevation angle.  
But, the cleaner pattern of a Yagi improves reception compared to the scaled Beverage.
In practice, a rotatable Yagi is the King of DX antennas.

Zack W1VT
« Last Edit: December 08, 2017, 12:50:05 PM by W1VT » Logged
KM1H
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Posts: 2633




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« Reply #8 on: December 08, 2017, 05:51:49 PM »

Back in the late 80's I had a 750' Beverage I used on 20M chasing a DXpedition since snow static made the 4el yagi useless.
Granted the signals were weak but that also minimized QRM in the pileup.

In the 90's at this location I used 500-750' Beverages many times on 20 for the same reason in a few contests. Far from ideal but luckily I didnt have software to tell me it wouldnt work. One CW DX contest we won because others in competition didnt have or think to try their Beverages.

Carl
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W1VT
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« Reply #9 on: December 08, 2017, 06:31:15 PM »

As I pointed out earlier, it really depends on location.  Most people don't have a good sloping ground to work with.  But, if you do, you can do amazingly well compared to "flat landers." But, I'd rather have the short six minute commute to work via state roads that are always plowed in the winter.  McDonalds, Best Buy, Target, Home Depot, Lowes, and Walmart all depend on those roads for police and fire services.
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KM1H
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« Reply #10 on: December 09, 2017, 01:17:51 PM »

Ive lived in this town since 73 at 150' ASL in a valley and then at 650' ASL on the highest point in 20+ miles.
For 160-40 which the Beverages were built for I couldnt tell any difference; they heard well for DX and contests. Beverages are not a very low angle antenna.

Using TX/RX on the same antennas it is a totally different world up here and programs such as TA make it easy to build for the needed elevation angles.

Im 10-15 minutes from where I used to work, Lowell MA and Nashua NH, plus all the malls at Salem NH are just as close so shopping choices is never an issue plus there is no Sales or State Income Tax in NH. I wont eat at McDonalds and my vehicles had zero problems in the snow/ice partially due to my superior driving skills Grin Shocked  Flatlanders stay away please Roll Eyes
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W1VT
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« Reply #11 on: December 09, 2017, 03:47:52 PM »

Which is precisely my point--why bother with high angle beverages when you can receive and transmit with low angles using a rotatable Yagi?  And, if you really needed a high angle directional antenna, you could just side mount a 3 element Yagi at a low height on the tower.
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KM1H
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« Reply #12 on: December 09, 2017, 05:35:44 PM »

And you consistently miss my point which is when the regular antenna is unusable due to precipitation static or other noise generators the Beverage is the difference between studying your navel and working someone.
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W1VT
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« Reply #13 on: December 09, 2017, 05:58:54 PM »

Reports I've read suggest that the lower Yagi does better with regard to precipitation static as well.  When you have a switchable stack which allows the higher Yagi(s) to take away some of that static.  An interesting idea to try would be to stack beverages to see if you could drain off some of that static with wires above the wire actually used for reception.

Zack W1VT
« Last Edit: December 09, 2017, 06:04:59 PM by W1VT » Logged
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