[HCARC] OOPS Wrong Receiving Antenna Link

[Gary and Arlene Johnson]

Well Maunder Minimum or not, therfe is no doubt that this Max was lower than 
the last which was lower than the one before so the trend is a quieting of 
the sun.  I want to know enough and have enough experience operating on the 
lower bands that I can do it comfortably.  My K3 given good ears can process 
weak signals as good as anyone's radio and therefore I should work the lower 
freqs as a habit, whenever they are open.

I agree, if the sunspots do go away for awhile, the lower bands ae going to 
get crowded and that will increase the noise on already noisy bands.  It's 
all about learning how to operate each and every place.

73's

Gary J
N5BAA
HCARC Secretary (2013)



----- Original Message ----- 
From: "Kerry Sandstrom" <kerryk5ks at hughes.net>
To: "Gary and Arlene Johnson" <qltfnish at omniglobal.net>; "Dale Gaudier" 
<dale.gaudier at gmail.com>
Cc: <hcarc at mailman.qth.net>
Sent: Saturday, November 17, 2012 3:04 PM
Subject: Re: [HCARC] OOPS Wrong Receiving Antenna Link


> Gary,
>
> I wouldn't worry about a new Maunder minimum.  To say that scientists 
> don't have a clue when it comes to predicting the sun is an 
> understatement.  Our ability to predict what is going to happen is very 
> limited.  There is some capability to predict the likelihood of a large 
> flare 1-3 days ahead and usually the most likely sunspot group can also be 
> predicted.  There is also some capability to predict in general terms what 
> the next solar rotation will be like, 27 days, but that is about it.  The 
> start of the next Maunder-like minimum has been postulated since the 
> 1960's.  Hasn't happened yet, but what is 50 years in the overall life of 
> the sun.
>
> There are actually two things that one needs to do, and that is whether we 
> have another long minimum or not.  The first is to be sure we have a 
> station that does an adequate job on 160 through 40 m.  These bands 
> require somewhat different techniques than the higher bands.  First, 
> antennas with gain are seldom practical for normal people.  Second, the 
> level of man-made QRN as well as atmospheric QRN is significantly higher 
> and you need to know and practice how to operate your rig to minimize the 
> impact of QRN.  Third, there will be a lot more activity on the lower 
> bands so you need to know and practice how to operate your rig with high 
> levels of QRM.  The second thing one must do if we enter another long 
> minimum as well as when we enter the next minimum of the 11 year cycle is 
> to know when conditions on the higher bands have momentarily improved. 
> Even during a solar minimum there are times when 10 and 15 meters are open 
> for long distance contacts.  These openings may only last for a few 
> minutes or a couple hours.  To some extent the openings depend on time of 
> day and season and are somewhat predictable. They also depend on curreent 
> solar-geophysical conditions.  The sun often has short bursts of activity 
> which can enhance conditions on the higher bands.  There are also 
> geomagnetic disturbances which may provide short openings using uncommon 
> propagation modes.  One needs to be able to spot when these things are 
> happening and know where to go and what to look for.
>
> Any of the so-called receiving antennas need a preamp.  The reason they 
> are called "receiving antennas" is because they are very inefficient, so 
> inefficient that they can't be used as a transmitting antenna.  The 
> nreason they are used is because they can be used to null out a noise 
> source or they are less susceptible to noise pickup.  A vertical is a good 
> transmitting antenna at low frequencies because it is an efficient 
> radiator.  It is not a good receiving antenna because much of the low 
> frequency QRN is vertically polarized and a vertically polarized antenna 
> picks the QRN up better than a horizontally polarized antenna. 
> Unfortunately, if you want to work DX with a horizontally polarized 
> antenna you have to get it well above the ground which is not easy to do.
>
> The Beverage was originally designed for use in VLF trans-atlantic.  The 
> US end of the circuit was in northern Maine.  The QRN was primarily from 
> the south and southwest, while the signals from Europe were from the 
> northeast. The Beverage did an excellent job of providing an improved 
> signal to noise ratio for the signals received from Europe.  It was a good 
> solution because the signals were all from the same direction and the 
> noise was from the opposite direction.  By the way, the Beverage can be 
> operated in either direction or both directions depending on how it is set 
> up.  The original Beverages received vertically polarized signals and 
> relied on the front-to-back ratio for the improved SNR.
>
> I think the most practical low noise receiving antenna is a small 
> rotatable loop as used in old DF systems.  The loop can be rotated to null 
> out the interference and improve the signal-to-noise ratio.  The old 
> 5-tube AC/DC AM broadcast receivers used a loop antenna and by rotating 
> the radio you could improve the SNR of the station you wanted to listen 
> to.  Early transistor ragios used a variation of a loop antenna called a 
> loopstick.  My Sony AM/FM receiver comes with a small loop antenna for B/C 
> band reception.
>
> You can use these very inefficient receiving antennas on the low frequency 
> ham bands because the signal strengths are very high as is the field 
> strength of the QRN.  This is the only reason the AM B/C band was ever 
> practical.  B/C band antennas, particularly automobile B/C band antennas 
> are terrible antennas with very high losses, but the field strengths of 
> the AM B/C transmitters are huge so it doesn't matter.  What matters is 
> SNR.
>
> Kerry
>
>
>
>
>
>
>
> -----
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