Re: Topband: Small Loop does not receive weak signal on 160m BOUVET RX SPOILER

[n0tt1]

I was one of the 160m ops at "nearby" FT5XO.  I can tell you that when
the
WX was good the TX antennas worked very well for receiving.  When the
WX turned bad, such as during the snow storm we worked through, the 160m
TX antennas
were very noisyjust as noisy as those anywhere on the planet.

Don't get me started about those awful 160m fishing buoy transmitters!!

73,
Charlie, N0TT

On Fri, 23 Dec 2022 19:45:28 -0700 Wes  writes:
> All interesting.  But let me ask (and standby for flames) what is 
> wrong with 
> them simply listening on the TX antenna?
> 
> I know, I know, conventional wisdom says that you can't possibly 
> work 160 DX 
> without a separate RX antenna.  I'll confess that I am a little 
> pistol and will 
> never be on the TB Honor Roll, but I got on the band just to add 
> another DXCC 
> band to my collection (now nine).  I'm now at 144 confirmed, 
> running just 500W 
> and a 55' inverted-L on both TX and RX. Generally speaking I hear 
> better that I 
> get out.
> 
> Looking at my chances of working 3Y the optimum time is their 
> sunrise (~3:30Z) 
> when I am in complete darkness and straight across the terminator. 
> They will 
> have the sunlit ocean to their rear and the S. American landmass 
> toward me.  
> Maybe someone can enlighten me, but I fail to see how a directional 
> antenna will 
> improve the SNR of my signal at their end.
> 
> Wes  N7WS
> 
> 
> On 12/23/2022 6:46 PM, JC wrote:
> > Hi topband lovers
> >
> >   
> >
> > Some friends contact me with deep concerns about the next Bouvet 
> DX expedition receiver antenna called SALAD
> >
> >   
> >
> >   
>
 
>  Salad antenna
> >
> >   
> >
> > I understand the concerns, Bouvet on 160m is a lifetime 
> opportunity for most top-banders!
> >
> >   
> >
> > When Doug NX4D, me N4IS and Dr Dallas started to try to understand 
> the limitation of the new Waller Flag, the first big question was;
> >
> >   
> >
> > How small a loop antenna can be to receive weak signal on 160, or 
> MW?
> >
> >   
> >
> > Dr. Dallas Lankford III (SK), measured the internal noise of a 
> small loop. 15x15 FT on his quiet QTH, and wrote a paper with the 
> derivation necessary to calculate the thermal noise of a small loop. 
> The study most important point was:
> >
> >   
> >
> > The sensitivity of small loop antennas can be limited by internally 
> generated thermal noise which is a characteristic of the loop 
> itself. Even amplifying the loop output with the lowest noise figure 
> preamp available may not improve the loop sensitivity if manmade 
> noise drops low enough
> >
> >   
> >
> > The noise on Bouvet island will be very low, < -120 dBm at 500Hz,  
> and for sure the internal thermal noise of the prosed RX antenna 
> will limit the reception of weak signals on 160m, it may work on 80 
> and above, but for 160 m, it will be a set up for failure.
> >
> >   
> >
> > Why not a single, trustable beverage antenna over the ice or 
> snow?? Or a proved K9AY or a DHDL??
> >
> >   
> >
> > Below is the almost good transcript of the original pdf Flag 
> Theory, for the long answer.
> >
> >   
> >
> >   
> >
> > 73�s
> >
> > JC
> >
> > N4IS
> >
> >   
> >
> > Flag Theory
> > Dallas Lankford, 1/31/09, rev. 9/9/09
> >
> >
> > The derivation which follows is a variation of Belrose's classical 
> derivation for ferrite rod loop antennas,
> > �Ferromagnetic Loop Aerials,� Wireless Engineer, February 
> 1955, 41� 46.
> >
> >
> > Some people who have not actually compared the signal output of a 
> flag antenna to other small antennas have expressed their opinions 
> to me that the signal output of a flag antenna has great attenuation 
> compared to those other small antennas, such as loops and passive 
> verticals. Their opinions are wrong. One should never express 
> opinions which are based, say, on computer simulations alone, 
> without actual measurements. The development below is based on 
> physics (including Maxwell's equations), mathematics, and 
> measurements.
> >
> >
> > Measurements have confirmed that the flag signal to noise formula 
> derived below is approximately correct despite EZNEC simulations to 
> the contrary. For example, EZNEC simulation of a 15' square loop at 
> 1 MHz predicts its gain is about +4 dbi, while on the other hand 
> EZNEC simulation of a 15' square flag at 1 MHz predicts its gain is 
> about �46 dBi. But if you construct such a loop and such a flag 
> and observe the signal strengths produced by them for daytime 
> groundwave MW signals, you will find that the maximum loop and flag 
> signal outputs are about equal. Although somewhat more difficult to 
> judge, the nighttime sky wave MW signals are also about equal.
> >
> >
> > Also, the signal to noise ratio formula below for flag arrays has 
> been verified by manmade noise measurements in the 160 meter band 
> using a smaller flag array than the MW flag array discussed below. 
> Several 

Re: Topband: Small Loop does not receive weak signal on 160m BOUVET RX SPOILER

[Jim Brown]

On 12/23/2022 8:12 PM, n...@comcast.net wrote:

I missed the second question.


I understand Wes's point quite well. I have friends who operate 6M from 
very remote places where there is no local noise to light up rare grids. 
They're rare because no one lives there to create noise.


The vast majority of active hams are surrounded by a LOT of noise 
generated by electronics in their own homes and those of their 
neighbors, as well from power lines, street lighting, and other sources. 
WE are the ones who most need serious RX antennas (and also to devote 
our energies to killing as much as possible of our noise at the source).


The difference in local noise between what WE hear and what the DX hears 
can easily be 20 dB.


What Wes may be missing is that the DX may be hearing stations from 
multiple directions, callers from areas with easy prop to them may be 
MUCH stronger than callers from areas that must be worked under exactly 
the right conditions and for rather short time windows, and that those 
loud callers may have a tendency to not stop calling. :) THAT'S where 
serious RX antennas can help at the DX location.


And as both Wes and I have observed, great system engineering involves 
devising systems to solve specific problems. One size never fits all.


73, Jim K9YC
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Small Loop does not receive weak signal on 160m BOUVET RX SPOILER

[n4is]

Wes 

I missed the second question. How a receiving antenna can help on your signal 
there. The RX antenna is good as the directivity or RDF. Based on my 
measurements and extensive experiments with the Waller Flag, for 1 db improve 
in RDF you can get 2db or more on signal to noise ratio aiming at the signal, 
plus de rejection on side and back nulls. You can check more about this on my 
webinar at WWROF

https://wwrof.org/webinar-archive/high-performance-rx-antennas-for-a-small-lot/

I measured 2db over 100 tests or more, including using WSJT SN readings. It is 
a practical result, not just computer simulation.

With a good RX antenna 11 to 12 dB RDF you can work 150 counties on 160 any 12 
month period. I did it for 10 years. Using  a Waller Flag, Doug NX4D, worked 
314 on 160m  from a 1/5 acre lot. All CW.

I  started with a vertical WF on 2003, and an Horizontal Waller Flag in 2010, 
the noise here in my city lot is very high now, and my Vertical Waller Flag is 
down because the HWF does not see the vertical manmade noise, so I have no 
noise on the HWF. I worked in the last 10 year close to 300 countries on 160m, 
only CW, and I am now at 305, however I heard over 320 countries down here in 
South Florida from a city lot. The VWF can dig signals on CW 10 db below noise 
and my HWF can dig 20 db bellow noise, when you compare with the TX antenna. I 
can measure that as well, with 2 instances on WSJT on my radio two identical 
receivers, a signal -20 SNR on the vertical shows a 0 db on the HWF. 

More information about the HWF here >

https://wwrof.org/webinar-archive/n4is-waller-flag-construction/

You can download the presentation too, Doug and I do not provide any additional 
support or question anymore, we spent hundred of hours on it and few people 
listened us.

So, conclusion a RX antenna can dig you signal out of the noise.

73's
JC
N4IS




-Original Message-
From: Topband  On Behalf Of Wes
Sent: Friday, December 23, 2022 9:45 PM
To: topband@contesting.com
Subject: Re: Topband: Small Loop does not receive weak signal on 160m BOUVET RX 
SPOILER

All interesting.  But let me ask (and standby for flames) what is wrong with 
them simply listening on the TX antenna?

I know, I know, conventional wisdom says that you can't possibly work 160 DX 
without a separate RX antenna.  I'll confess that I am a little pistol and will 
never be on the TB Honor Roll, but I got on the band just to add another DXCC 
band to my collection (now nine).  I'm now at 144 confirmed, running just 500W 
and a 55' inverted-L on both TX and RX. Generally speaking I hear better that I 
get out.

Looking at my chances of working 3Y the optimum time is their sunrise (~3:30Z) 
when I am in complete darkness and straight across the terminator. They will 
have the sunlit ocean to their rear and the S. American landmass toward me. 
Maybe someone can enlighten me, but I fail to see how a directional antenna 
will improve the SNR of my signal at their end.

Wes  N7WS


On 12/23/2022 6:46 PM, JC wrote:
> Hi topband lovers
>
>   
>
> Some friends contact me with deep concerns about the next Bouvet DX 
> expedition receiver antenna called SALAD
>
>   
>
>   
>  a.php>  Salad antenna
>
>   
>
> I understand the concerns, Bouvet on 160m is a lifetime opportunity for most 
> top-banders!
>
>   
>
> When Doug NX4D, me N4IS and Dr Dallas started to try to understand the 
> limitation of the new Waller Flag, the first big question was;
>
>   
>
> How small a loop antenna can be to receive weak signal on 160, or MW?
>
>   
>
> Dr. Dallas Lankford III (SK), measured the internal noise of a small loop. 
> 15x15 FT on his quiet QTH, and wrote a paper with the derivation necessary to 
> calculate the thermal noise of a small loop. The study most important point 
> was:
>
>   
>
> The sensitivity of small loop antennas can be limited by internally 
> generated thermal noise which is a characteristic of the loop itself. 
> Even amplifying the loop output with the lowest noise figure preamp 
> available may not improve the loop sensitivity if manmade noise drops 
> low enough
>
>   
>
> The noise on Bouvet island will be very low, < -120 dBm at 500Hz,  and for 
> sure the internal thermal noise of the prosed RX antenna will limit the 
> reception of weak signals on 160m, it may work on 80 and above, but for 160 
> m, it will be a set up for failure.
>
>   
>
> Why not a single, trustable beverage antenna over the ice or snow?? Or a 
> proved K9AY or a DHDL??
>
>   
>
> Below is the almost good transcript of the original pdf Flag Theory, for the 
> long answer.
>
>   
>
>   
>
> 73’s
>
> JC
>
> N4IS
>
>   
>
> Flag Theory
> Dallas Lankford, 1/31/09, rev. 9/9/09
>
>
> The derivation which follows is a variation of Belrose's classical 
> derivation for ferrite rod loop antennas, “Ferromagnetic Loop Aerials,” 
> Wireless Engineer, February 1955, 41– 46.
>
>
> Some people who 

Re: Topband: Small Loop does not receive weak signal on 160m BOUVET RX SPOILER

[Wes]

All interesting.  But let me ask (and standby for flames) what is wrong with 
them simply listening on the TX antenna?


I know, I know, conventional wisdom says that you can't possibly work 160 DX 
without a separate RX antenna.  I'll confess that I am a little pistol and will 
never be on the TB Honor Roll, but I got on the band just to add another DXCC 
band to my collection (now nine).  I'm now at 144 confirmed, running just 500W 
and a 55' inverted-L on both TX and RX. Generally speaking I hear better that I 
get out.


Looking at my chances of working 3Y the optimum time is their sunrise (~3:30Z) 
when I am in complete darkness and straight across the terminator. They will 
have the sunlit ocean to their rear and the S. American landmass toward me.  
Maybe someone can enlighten me, but I fail to see how a directional antenna will 
improve the SNR of my signal at their end.


Wes  N7WS


On 12/23/2022 6:46 PM, JC wrote:

Hi topband lovers

  


Some friends contact me with deep concerns about the next Bouvet DX expedition 
receiver antenna called SALAD

  


    
Salad antenna

  


I understand the concerns, Bouvet on 160m is a lifetime opportunity for most 
top-banders!

  


When Doug NX4D, me N4IS and Dr Dallas started to try to understand the 
limitation of the new Waller Flag, the first big question was;

  


How small a loop antenna can be to receive weak signal on 160, or MW?

  


Dr. Dallas Lankford III (SK), measured the internal noise of a small loop. 
15x15 FT on his quiet QTH, and wrote a paper with the derivation necessary to 
calculate the thermal noise of a small loop. The study most important point was:

  


The sensitivity of small loop antennas can be limited by internally generated 
thermal noise which is a characteristic of the loop itself. Even amplifying the 
loop output with the lowest noise figure preamp available may not improve the 
loop sensitivity if manmade noise drops low enough

  


The noise on Bouvet island will be very low, < -120 dBm at 500Hz,  and for sure 
the internal thermal noise of the prosed RX antenna will limit the reception of 
weak signals on 160m, it may work on 80 and above, but for 160 m, it will be a set 
up for failure.

  


Why not a single, trustable beverage antenna over the ice or snow?? Or a proved 
K9AY or a DHDL??

  


Below is the almost good transcript of the original pdf Flag Theory, for the 
long answer.

  

  


73’s

JC

N4IS

  


Flag Theory
Dallas Lankford, 1/31/09, rev. 9/9/09


The derivation which follows is a variation of Belrose's classical derivation 
for ferrite rod loop antennas,
“Ferromagnetic Loop Aerials,” Wireless Engineer, February 1955, 41– 46.


Some people who have not actually compared the signal output of a flag antenna 
to other small antennas have expressed their opinions to me that the signal 
output of a flag antenna has great attenuation compared to those other small 
antennas, such as loops and passive verticals. Their opinions are wrong. One 
should never express opinions which are based, say, on computer simulations 
alone, without actual measurements. The development below is based on physics 
(including Maxwell's equations), mathematics, and measurements.


Measurements have confirmed that the flag signal to noise formula derived below 
is approximately correct despite EZNEC simulations to the contrary. For 
example, EZNEC simulation of a 15' square loop at 1 MHz predicts its gain is 
about +4 dbi, while on the other hand EZNEC simulation of a 15' square flag at 
1 MHz predicts its gain is about –46 dBi. But if you construct such a loop and 
such a flag and observe the signal strengths produced by them for daytime 
groundwave MW signals, you will find that the maximum loop and flag signal 
outputs are about equal. Although somewhat more difficult to judge, the 
nighttime sky wave MW signals are also about equal.


Also, the signal to noise ratio formula below for flag arrays has been verified 
by manmade noise measurements in the 160 meter band using a smaller flag array 
than the MW flag array discussed below. Several years ago a similar signal to 
noise ratio formula for small un-tuned (broadband) loop antennas was verified 
at the low end of the NDB band.


The signal voltage es in volts for a one turn loop of area A in meters and a 
signal of wavelength λ for a given radio wave is

  


es = [2πA Es /λ] COS(θ)

  


where Es is the signal strength in volts per meter and θ is the angle between 
the plane of the loop and the radio wave. It is well known that if an 
omnidirectional antenna, say a short whip, is attached to one of the output 
terminals of the loop and the phase difference between the loop and vertical 
and the amplitude of the whip are adjusted to produce a cardioid patten, then 
this occurs for a phase difference of 90 degrees and a whip amplitude equal to 
the amplitude of the loop, and the signal voltage 

Re: Topband: Small Loop does not receive weak signal on 160m BOUVET RX SPOILER

[n4is]

Doug NX4D asked me to add his comments,

Hey JC and Topbanders,  This is meant as a suggestion, not a criticism. 

The reason I sounded an alarm to JC was the concern that the proposed SALAD/ 
LZ1AQ 160m receive loops by the upcoming Bouvet DXpedition/ 3Y0J are  much too 
small for receiving weak signals on 160m.  With the current poor 160m condx, it 
would be a shame for them to go to all this trouble and expense, then not be 
able to pull in medium to weaker sigs with the loops.  I would suggest the 
loop(s) be at least 10 ft (3m) diameter.

>From experience I found that my original WF with small phased loops could not 
>hear the weakest sigs others around me were hearing, due to being thermal 
>noise limited.  The solution was to make the loops much larger, by which I 
>could then hear all sigs very well.

73/ NX4D

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: Small Loop does not receive weak signal on 160m BOUVET RX SPOILER

[JC]

Hi topband lovers

 

Some friends contact me with deep concerns about the next Bouvet DX expedition 
receiver antenna called SALAD

 

  
Salad antenna

 

I understand the concerns, Bouvet on 160m is a lifetime opportunity for most 
top-banders!

 

When Doug NX4D, me N4IS and Dr Dallas started to try to understand the 
limitation of the new Waller Flag, the first big question was;

 

How small a loop antenna can be to receive weak signal on 160, or MW? 

 

Dr. Dallas Lankford III (SK), measured the internal noise of a small loop. 
15x15 FT on his quiet QTH, and wrote a paper with the derivation necessary to 
calculate the thermal noise of a small loop. The study most important point was:

 

The sensitivity of small loop antennas can be limited by internally generated 
thermal noise which is a characteristic of the loop itself. Even amplifying the 
loop output with the lowest noise figure preamp available may not improve the 
loop sensitivity if manmade noise drops low enough

 

The noise on Bouvet island will be very low, < -120 dBm at 500Hz,  and for sure 
the internal thermal noise of the prosed RX antenna will limit the reception of 
weak signals on 160m, it may work on 80 and above, but for 160 m, it will be a 
set up for failure.

 

Why not a single, trustable beverage antenna over the ice or snow?? Or a proved 
K9AY or a DHDL??

 

Below is the almost good transcript of the original pdf Flag Theory, for the 
long answer.

 

 

73’s

JC

N4IS

 

Flag Theory
Dallas Lankford, 1/31/09, rev. 9/9/09 


The derivation which follows is a variation of Belrose's classical derivation 
for ferrite rod loop antennas,
“Ferromagnetic Loop Aerials,” Wireless Engineer, February 1955, 41– 46.


Some people who have not actually compared the signal output of a flag antenna 
to other small antennas have expressed their opinions to me that the signal 
output of a flag antenna has great attenuation compared to those other small 
antennas, such as loops and passive verticals. Their opinions are wrong. One 
should never express opinions which are based, say, on computer simulations 
alone, without actual measurements. The development below is based on physics 
(including Maxwell's equations), mathematics, and measurements.


Measurements have confirmed that the flag signal to noise formula derived below 
is approximately correct despite EZNEC simulations to the contrary. For 
example, EZNEC simulation of a 15' square loop at 1 MHz predicts its gain is 
about +4 dbi, while on the other hand EZNEC simulation of a 15' square flag at 
1 MHz predicts its gain is about –46 dBi. But if you construct such a loop and 
such a flag and observe the signal strengths produced by them for daytime 
groundwave MW signals, you will find that the maximum loop and flag signal 
outputs are about equal. Although somewhat more difficult to judge, the 
nighttime sky wave MW signals are also about equal.


Also, the signal to noise ratio formula below for flag arrays has been verified 
by manmade noise measurements in the 160 meter band using a smaller flag array 
than the MW flag array discussed below. Several years ago a similar signal to 
noise ratio formula for small un-tuned (broadband) loop antennas was verified 
at the low end of the NDB band.


The signal voltage es in volts for a one turn loop of area A in meters and a 
signal of wavelength λ for a given radio wave is

 

es = [2πA Es /λ] COS(θ) 

 

where Es is the signal strength in volts per meter and θ is the angle between 
the plane of the loop and the radio wave. It is well known that if an 
omnidirectional antenna, say a short whip, is attached to one of the output 
terminals of the loop and the phase difference between the loop and vertical 
and the amplitude of the whip are adjusted to produce a cardioid patten, then 
this occurs for a phase difference of 90 degrees and a whip amplitude equal to 
the amplitude of the loop, and the signal voltage in this case is 

 

es = [2πA Es /λ] [1 + COS(θ)] 

.
Notice that the maximum signal voltage of the cardioid antenna is twice the 
maximum signal voltage of the loop (or vertical) alone. 

A flag antenna is a one turn loop antenna with a resistance of several hundred 
ohms inserted at some point into the one turn. With a rectangular turn, with 
the resistor appropriately placed and adjusted for the appropriate value, the 
flag antenna will generate a cardioid pattern. The exact mechanism by which 
this occurs is not given here. Nevertheless, based on measurements, the flag  
antenna signal voltage is approximately the same as the cardioid pattern given 
above. The difference between an actual flag and the cardioid pattern above is 
that an actual flag pattern is not a perfect cardioid for some cardioid 
geometries and resistors. 

 

In general a flag pattern will be 

es = [2πA Es /λ] [1 + kCOS(θ)] 

 

where k is a constant less than or equal to 1,