Re: Topband: making a bev seem longer

[Phil Duff]

Perhaps magnetic loop was an incorrect term - shielded-loop is better.

Yes - there are better low-band RX antennas.  I also have a Hi-Z 3 element 
vertical triangle array.  It works, has directivity and decent rear rejection. 

However, my triangle array has higher S/N than my shielded-loop.   

My log book shows that on 160 and 80m my shielded-loop hears plenty of DX and 
should not be dismissed as only being good for local RFI and QSOs.  I don’t 
rotate my loop - It does have a narrow null perpendicular to the plane of the 
loop but the null is not noticeable in practical operation with proper loop 
orientation.

For those who would like to improve their low-band S/N without the real estate 
and/or $$ and effort to buy/build Beverages, BOGs, multi-element vertical 
arrays, steerable loops, etc. a shielded-loop could make a noticeable 
improvement in their low-band RX S/N. 

73 Phil NA4M


> On Aug 7, 2018, at 4:58 PM, Mike Waters  wrote:
> 
> A loop such as that has a very narrow null at very low angles, and therefore 
> it's usually not very effective for anything except for local RFI or another 
> local ham. For power line or nearby QRN, it's useful. But that's about it. 
> There are much better RX antennas.
> 
> 73, Mike
> www.w0btu.com 
> 
> On Mon, Aug 6, 2018, 7:37 PM Phil Duff  > wrote:
> > On Aug 6, 2018, at 7:06 PM, Cecil Acuff  > > wrote:
> >  Wish I could find an effective RX antenna that showed a great s/n 
> > improvement over the L.
> 
> Look into a magnetic loop such as the design by N6RK as described in a past 
> NCJ:
> 
> http://www.n6rk.com/loopantennas/NCJ_loop_antenna_N6RK.pdf 
> 
> 
> I use one on 160/80 and find it effective at improving the S/N ratio over my 
> vertically polarized 160m and 80m transmit antennas.
> 
> 
> de Phil NA4M
> 

-. .- ….- --
Phil Duff  na4m[at]suddenlink[dot]net
















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Re: Topband: making a bev seem longer

[Cecil Acuff]

Don’t have that much room. My available space is about 150’ x 250’ with the 
tower in middle of it. House separates that area from the front yard which is 
150’ x 150’. Had the K9AY in the front yard, also tried the SAL-30 there. Very 
directional but couldn’t hear Europe any better than on the L. Tried a BOG but 
it may have been too long. Probably 300-350’ It went across the top of my 
radial field for the tower/L. (And into half of the neighbors front yard) 
Pointed towards EUcompletely deaf compared to the L.

Haven’t given up hope...

Cecil
K5DL



> On Aug 7, 2018, at 6:06 PM, Mike Waters  wrote:
> 
> I also live in a very quiet location. But put up a directional one-wavelength 
> Beverage pointed at Europe, Asia, Oceana, or Africa, and you'll see how much 
> noise that you really have! :-)
> 
> 73, Mike
> www.w0btu.com
> Please see my Beverage antenna information there
> 
>> On Tue, Aug 7, 2018, 5:53 PM chacuff  wrote:
>> I don't have problems with noise...which may be why RX antennas don't 
>> perform a whole lot better than my TX antenna. I wouldn't say it's extremely 
>> quiet but it's not excessively noisy.  Hope to play more with antennas this 
>> fall and winter.
>> 
>> Cecil
>> 
>>  Original message 
>> From: Mike Waters  
>> Date: 8/7/18 4:58 PM (GMT-06:00) 
>> To: Phil Duff  
>> Cc: topband  
>> Subject: Re: Topband: making a bev seem longer 
>> 
>> A loop such as that has a very narrow null at very low angles, and
>> therefore it's usually not very effective for anything except for local RFI
>> or another local ham. For power line or nearby QRN, it's useful. But that's
>> about it. There are much better RX antennas.
>> 
>> 73, Mike
>> www.w0btu.com
>> 
>> On Mon, Aug 6, 2018, 7:37 PM Phil Duff  wrote:
>> 
>> > > On Aug 6, 2018, at 7:06 PM, Cecil Acuff  wrote:
>> > >  Wish I could find an effective RX antenna that showed a great s/n
>> > improvement over the L.
>> >
>> > Look into a magnetic loop such as the design by N6RK as described in a
>> > past NCJ:
>> >
>> > http://www.n6rk.com/loopantennas/NCJ_loop_antenna_N6RK.pdf
>> >
>> > I use one on 160/80 and find it effective at improving the S/N ratio over
>> > my vertically polarized 160m and 80m transmit antennas.
>> >
>> >
>> > de Phil NA4M
>> 
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Re: Topband: making a bev seem longer

[Mike Waters]

I also live in a very quiet location. But put up a directional
one-wavelength Beverage pointed at Europe, Asia, Oceana, or Africa, and
you'll see how much noise that you *really* have! :-)

73, Mike
www.w0btu.com
Please see my Beverage antenna information there

On Tue, Aug 7, 2018, 5:53 PM chacuff  wrote:

> I don't have problems with noise...which may be why RX antennas don't
> perform a whole lot better than my TX antenna. I wouldn't say it's
> extremely quiet but it's not excessively noisy.  Hope to play more with
> antennas this fall and winter.
>
> Cecil
>
>  Original message 
> From: Mike Waters 
> Date: 8/7/18 4:58 PM (GMT-06:00)
> To: Phil Duff 
> Cc: topband 
> Subject: Re: Topband: making a bev seem longer
>
> A loop such as that has a very narrow null at very low angles, and
> therefore it's usually not very effective for anything except for local RFI
> or another local ham. For power line or nearby QRN, it's useful. But that's
> about it. There are much better RX antennas.
>
> 73, Mike
> www.w0btu.com
>
> On Mon, Aug 6, 2018, 7:37 PM Phil Duff  wrote:
>
> > > On Aug 6, 2018, at 7:06 PM, Cecil Acuff  wrote:
> > >  Wish I could find an effective RX antenna that showed a great s/n
> > improvement over the L.
> >
> > Look into a magnetic loop such as the design by N6RK as described in a
> > past NCJ:
> >
> > http://www.n6rk.com/loopantennas/NCJ_loop_antenna_N6RK.pdf
> >
> > I use one on 160/80 and find it effective at improving the S/N ratio over
> > my vertically polarized 160m and 80m transmit antennas.
> >
> >
> > de Phil NA4M
>
>
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Re: Topband: making a bev seem longer

[chacuff]

I don't have problems with noise...which may be why RX antennas don't perform a 
whole lot better than my TX antenna. I wouldn't say it's extremely quiet but 
it's not excessively noisy.  Hope to play more with antennas this fall and 
winter.
Cecil


Sent from my Verizon, Samsung Galaxy smartphone

 Original message 
From: Mike Waters  
Date: 8/7/18  4:58 PM  (GMT-06:00) 
To: Phil Duff  
Cc: topband  
Subject: Re: Topband: making a bev seem longer 

A loop such as that has a very narrow null at very low angles, and
therefore it's usually not very effective for anything except for local RFI
or another local ham. For power line or nearby QRN, it's useful. But that's
about it. There are much better RX antennas.

73, Mike
www.w0btu.com

On Mon, Aug 6, 2018, 7:37 PM Phil Duff  wrote:

> > On Aug 6, 2018, at 7:06 PM, Cecil Acuff  wrote:
> >  Wish I could find an effective RX antenna that showed a great s/n
> improvement over the L.
>
> Look into a magnetic loop such as the design by N6RK as described in a
> past NCJ:
>
> http://www.n6rk.com/loopantennas/NCJ_loop_antenna_N6RK.pdf
>
> I use one on 160/80 and find it effective at improving the S/N ratio over
> my vertically polarized 160m and 80m transmit antennas.
>
>
> de Phil NA4M
>
>
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Re: Topband: making a bev seem longer

[Mike Waters]

A loop such as that has a very narrow null at very low angles, and
therefore it's usually not very effective for anything except for local RFI
or another local ham. For power line or nearby QRN, it's useful. But that's
about it. There are much better RX antennas.

73, Mike
www.w0btu.com

On Mon, Aug 6, 2018, 7:37 PM Phil Duff  wrote:

> > On Aug 6, 2018, at 7:06 PM, Cecil Acuff  wrote:
> >  Wish I could find an effective RX antenna that showed a great s/n
> improvement over the L.
>
> Look into a magnetic loop such as the design by N6RK as described in a
> past NCJ:
>
> http://www.n6rk.com/loopantennas/NCJ_loop_antenna_N6RK.pdf
>
> I use one on 160/80 and find it effective at improving the S/N ratio over
> my vertically polarized 160m and 80m transmit antennas.
>
>
> de Phil NA4M
>
>
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Re: Topband: BOGs and dipoles on the ground

[n4is]

Hi Jerry

If you want to play with a very high performance EWE array, you can try this
one.

5m high , 7 m wide, 7m spaced, 4 EWE's in line. 49m total.

1st  EWE   10 degree  510 ohms
2nd EWE 190 degree 540 ohms
3nd EWE 180 degree 510 ohms
4nd EWE 0  degree 540 ohms

This antenna is narrow as 57 degree and punch a 13.8 db RDF, 160 to 40 m.

I prefer Delta Flags on the same configuration, you can get over 14 db RDF,
not much difference, but I can install it 1m over my metal fence.

I am building 2 x 4 EWE at 90 degree, on a corner, and it is possible to
switch 8 directions, but not with the same RDF. 

I hope to work JT for my last zone on 160m.

73's
JC
N4IS


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Topband: BOGs and dipoles on the ground

[K4SAV]

I may as well give you the results of my measurements with BOGs and 
dipoles on the ground.  It seems to be a lot different from the data I 
am hearing from other people.


This experimentation started when I tried to correlate the current in a 
BOG as predicted by EZNEC to an actual measurement.  The results were 
worlds apart.  It seems the current on a BOG disappears much faster down 
the wire than NEC predicts.  It really dissipates in a hurry as 
frequency as increased.  If NEC can't correctly predict the current in 
the wire, it can't correctly predict the pattern.


So then I tried a dipole on the ground to try and estimate the velocity 
factor of that wire.  The dipole was 119 ft total length (because that 
is what the length of the piece of wire I picked up was).   I left that 
wire on the ground for a month and periodically measured it.  The 
results were highly unpredictable, at least by NEC.  I can only 
attribute this variablilty to ground moisture variation, although I 
never measured it right after a rain.  To give you a feeling of the 
variability, here are the results of a few of the measurements.


1. F = 2.75 MHz, X = 0, R = 186 ohms,  also f = 6.25 MHz, X = 0, R = 522
2. F = 3.37 MHz, X = 0, R = 182, also close to resonance at frequencies 
above 8 MHz with R of about 440 ohms
3. F = 3.00 MHz, X = 0, R = 178 ohms, also F = 4.6 MHz, X = 0, R = 710 
ohms, also F = 7.0 MHz, X= 0, R = 562 ohms'

4. F = 2.70 MHz, X = 0, R = 167 ohms, also F = 4.5 MHz, X = 0, R = 675 ohms

You won't be able to predict those numbers using NEC.  NEC says the 
resonant frequency of this dipole should be about 2.8 MHz with R = 97 
ohms.  You can get some variation in that depend on the ground constants 
you select but you will never be able to come close to the measured data 
no matter what ground constants you choose.  (Actual ground is typical 
Alabama red clay with dipole 1 to 1.5 inches above it.)  You may be able 
to get NEC to give agreement to the feedpoint impedance at the lowest 
resonant frequency by selecting a ridiculous ground constant, but 
everything above that frequency will be way off.  NEC says the impedance 
should rise rapidly above the resonant point and and there are no other 
resonant points until you get to about 9.1 MHz.  So once again, like the 
BOG, NEC can't predict the pattern of this dipole on the ground.  Degree 
of error is unknown.


Incidentally, N6LF's pattern for a BOG computed with NEC4 I was able to 
duplicate.using NEC2.  So I have no confidence that NEC4 can predict the 
pattern of a BOG either.


So what to do?  If I can't compute the pattern of a wire on the ground, 
the only thing left is measurements.  I was also concerned with all the 
rules generated by other people for building BOGs because I know that 
data was generated from NEC analysis.  I duplicated those rules by doing 
the same analysis.  I also generated some new rules for improving BOGs 
generated from NEC but when I implemented that and made actual 
measurements, there was no improvement.  Thankfully I measured the 
results before publishing those rules.


So I set up an experiment using a 366 ft BOG and a 250 ft BOG both 
pointed in the same direction (to EU)  I spent a month taking data on 
signals from all directions, both close stations and DX stations, and 
compiling the differences in performance between the two.


A brief summary of these two antennas was that the forward gain of both 
was the same and the front to back was the same, at least within a 
degree of accuracy that made any practical difference. (It was not 
measurable.)  That was the same on 80 and 160.  The forward pattern of 
the shorter BOG was wider so the response at 90 degrees off forward was 
stronger.  The response for high angle signals was greater for the short 
BOG.  The shorted BOG has a wider front lobe both in the azimuth and 
elevation directions. The response at 120 degrees off forward was 
greater for the long BOG. That means the resulting signal to noise ratio 
should depend on where the noise sources are located.  In general with 
low noise sources, which is usually the case at my location, there was 
no detectable difference between the two.  Both of these antennas played 
well on 80 and 160.  The shorter antenna was better on 40.


If you do a NEC analysis of 250 and 366 ft BOGs, the beamwidth 
difference between the two will be as I measured, although the degree of 
difference may or may not be the same.  I didn't try to make an actual 
dB difference measurement, which is very difficult with over the air 
signals.  I also can't speculate the error in pattern produced by NEC 
when it has big errors in the current in the wire.


I also don't believe the RDF number for a BOG produced by NEC.  I can 
get an RDF for about 11 for a 366 ft BOG.  A BOG is a good antenna but 
it's not that good.  Many years ago I chose 366 ft based on a NEC 
analysis and it has worked well.  I will arrive at a better RDF for a 
366 ft BOG 

Re: Topband: making a bev seem longer

[Grant Saviers]

Agree, my DX Eng 4 sq vertical array (high impedance) is almost always 
the winner on 160 vs an 85' T, a toss up with a 2L beam @157' on 80m, 
and rarely better than the 3L 40m @ 140'.   So I believe the 4sq RDF 
numbers are valid.  Another plus: when p-static kills the 80m beam the 
4sq is the go to Rx antenna.


I was advised that exact radial symmetry is important to get the best 
pattern.  i.e. the same length, buried, and compass azimuths on the 
radials for each vertical.  W8JI also advises this also for short loaded 
vertical 4sq receive arrays and when I built one it worked.


https://www.w8ji.com/small_vertical_arrays.htm

Grant KZ1W


On 8/6/2018 16:21 PM, Chortek, Robert L. wrote:

Not to hijack the thread, but...

My Hi-Z Array works reasonably well in 160 (despite being only 40’ per side) 
and very well on both 80 and 40.  It has allowed me to work many countries on 
80 and 160 I would not otherwise have been able to hear.

To me, it was worth the effort.

73,

Bob AA6VB

Sent from my iPhone


On Aug 6, 2018, at 4:17 PM, WW3S  wrote:

I put a 3 ele hi z array up last fall, and it's not worth a tinkers damat 
least to me.may be some local noiseit certainly has directivity, at 
least on the bcb, so so on 80, but on 160, which was my primary interest, never 
worked well, never better than my reversible ewe, which is probably going back 
up this fall


Sent from my iPad


On Aug 6, 2018, at 6:20 PM, Tim Childers K9CQ  wrote:

I have been using the Hi-Z 3 element at 50 foot spacing that Lee designed. I 
can tell you that the results for me were amazing and it gives you 6 
directions.  It works quite well on 40, 80 and 160.  You can also find them at 
DX Engineering.

Tim, K9CQ


-Original Message- From: l...@k7tjr.com
Sent: Monday, August 6, 2018 4:32 PM
To: topband@contesting.com
Subject: Re: Topband: making a bev seem longer

First let me apologize if you get this e-mail twice as I have been having
problems with MSN.com.

Hi JC,
Not all vertical arrays are mono band. A well built 4-square on a 60 foot
per side can do a stellar job on 160, 80, and 40 meters while extending well
down into the broadcast band. The 3 element as well as the 4-square based 8
element on an 85 foot diameter circle will do the same thing.

Lee   K7TJR


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Re: Topband: Shunt Fed Tower Question

[Herbert Schoenbohm]

Herbert Schoenbohm 
Thu, Aug 2, 10:04 AM (5 days ago)
to TopBand
I recently installed a 2 element 40-meter beam and a 4 element 20-meter
beam on top of a 90-foot tower which I use for TX on Topband.  The tower is
cage fed with a 3-wire cage spaced24 inches around the tower,  I am able to
get 1.2 to 1 on 1845 by putting about 1200 pf and a 500 pf fixed HV cap to
ground.  The coax feed goes to the wires with about 40 mh in series.  My
taps to the tower are at 60' which may be too high up on the tower
considering all the toploading I have now.  My question is:  How far down
should I move the tower taps to make the feed appear inductive rather than
the capacitive value currently what I believe I have?

Any suggestions would be appreciated.

Thanks,

Herb Schoenbohm, KV4FZ

On Thu, Aug 2, 2018 at 10:04 AM Herbert Schoenbohm <
herbert.schoenb...@gmail.com> wrote:

> I recently installed a 2 element 40-meter beam and a 4 element 20-meter
> beam on top of a 90-foot tower which I use for TX on Topband.  The tower is
> cage fed with a 3-wire cage spaced24 inches around the tower,  I am able to
> get 1.2 to 1 on 1845 by putting about 1200 pf and a 500 pf fixed HV cap to
> ground.  The coax feed goes to the wires with about 40 mh in series.  My
> taps to the tower are at 60' which may be too high up on the tower
> considering all the toploading I have now.  My question is:  How far down
> should I move the tower taps to make the feed appear inductive rather than
> the capacitive value currently what I believe I have?
>
> Any suggestions would be appreciated.
>
> Thanks,
>
> Herb Schoenbohm, KV4FZ
>
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Re: Topband: Topband Digest, Vol 188, Issue 7

[Larry]

 Mike K wrote in part >>>

Message: 2 Date: Mon, 6 Aug 2018 12:06:12 -0500 From: Mikek


I have installed a 253ft Bog, ?I used WD-1A a pair and just twisted the
two wires together. Any reason I should separate the pair and just use a
single wire? Can the WD-1A be used for a Bi-directional BOG, or is the
spacing too close?

Mike:

Several things: 

  * I have tried bi-directional BOGs at my QTH and what I found with my
ground is that the losses on the direction using the double wire for
a return transmission line were very high, about 40 db or more when
leaves got on the antenna. I got signal at the far end, but by the
time it traveled back 250' along the parallel pair it had been
significantly attenuated. Your ground may be different;  you may
want to try Rudy Severn's ground test method using an 80 meter
dipole to determine your ground characteristics, but at my QTH (WV
rocks and highly conductive clay soils) the "return BOGs" were
essentially useless, and I now use only unidirectional BOGs. 
  * As Guy noted, the ground characteristics can (and at my QTH
defintely do!) vary significantly, and this is another hurdle to
overcome which I suspect affects return line losses for 2-way BOGs.
  * As others have noted, ground moisture can make a huge difference in
performance especially for some sorts of clay soils like those I have.
  * I did find that termination of the BOGs helps with F/B, and varying
the resistance can change the pattern of one of my BOGs enough to
help null 'town noise' from a town about 5 miles away.
  * getting the termination resistance right also helps with multiband
operation by keeping the impendance excursions down so that the BOG
works more consistently on 160, 80 and 40.

The things about BOGs that I like is that they are quick, cheap, easy to
install well, require no supports of any kind, and very low profile.

Regards and good luck with your BOGs!
LArry W8ANT

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