[HCARC] Solar Activity - The Bottom Line

Fri May 2 17:13:00 EDT 2014

Thanks Gary.  I really would welcome questions on the subject.  I hope 
that summary helps.

By the way, I see Microsoft has sent out security updates for Internet 
Explorer 9 and 11.  No indication if that solves the problem or not.  
For the record I'm using Mozilla Firefox for a browser and Mozilla 
Thunderbird for e-mail now.  works fine for me, better than Microsoft as 
a matter of fact.  And the price was right!

73,

Kerry
On 5/2/2014 3:25 PM, Gary J - N5BAA wrote:
> GOOD SHOW KERRY - LOTS OF GREAT INFO FOR NEW(ER) HAMS.  THANKS MUCH.
>
> Gary J
> N5BAA
>
> -----Original Message----- From: Kerry Sandstrom
> Sent: Friday, May 2, 2014 10:33 AM
> To: hcarc at mailman.qth.net
> Subject: [HCARC] Solar Activity - The Bottom Line
>
> Gary, N5BAA, told me at the May club meeting that I hadn't provided a
> bottom line to my April talk on solar activity.  I guess that's
> correct.  i probably didn't emphasize what a new ham should be looking
> for.  This is the bottom line in a few parts.  The first part
> re-emphasizes the need for detailed record keeping.  The second part
> expands a little bit on MUF, Maximum Usable Frequency.  The third part
> describes the normal daily cycle on the HF bands.
>
> Detailed record keeping is a big help in your determination of what to
> expect with your station at your location.  It also lets you see how
> changes you make affects your station performance.  Without detailed
> records, you will never know if you have made improvements or not.  Not
> only should you keep track of who you work, but also who you hear and
> what the solar/geomagnetic conditions are at the time.
>
> MUF is used in several different ways by different people.  f_0 F_2 is
> the vertical incidence critical frequency for the F_2 -layer , the
> highest frequency that will be returned to earth.  If you are interested
> in NVIS, Near Vertical Incidence Skywave, this is the parameter you are
> interested in.   As the distance increases, the MUF also increases until
> you reach the maximum single hop F-layer distance,  approximately 4000
> km/2500 miles.  This assumes a takeoff angle of 0º, hopeful but unlikely
> for any ham station.  Typical takeoff angles are 30º or more and the
> maximum single hop distance is considerably less than 4000 km.
> Distances beyond your maximum single hop distance require 2 or more
> hops.  The MUF for multiple hops is lower than for single hops and the
> signal losses are higher.  Stations with antennas high above the ground,
> 1 or 2 or more wavelengths, will have lower takeoff angles and have
> better signals working DX.  Stations with vertical antennas and good
> ground systems will also have lower takeoff angles.  When you make
> changes in your antenna, records of who you have heard and their signal
> strengths are the only practical way you can compare the performance of
> your antenna before and after you make changes.
>
> The normal daily cycle of an MF/HF band is as follows.  Early morning,
> well before sunrise, the MUF will be at its minimum.  You will not hear
> close in stations on skywave.  As sunrise approaches, you will notice
> signals from the east will start to come from closer and closer
> locations.  This happens very quickly between the half hour before
> sunrise and the half hour after sunrise.  The band will be fairly stable
> for the rest of the day.  On the lower frequencies, the signals,
> particularly from the farther distance, will become noticeably weaker
> during the day as the D-layer becomes denser and the absorption
> increases.  This is very noticeable on 80 and 40 m and not noticeable on
> 10 m.  As sunset approaches, the reverse process occurs, the closer in
> stations from the east start to drop out and eventually the stations
> farther to the east drop out. Eventually the close in stations from the
> west drop out and eventually the west coast stations drop out. The
> stations from the east coast sometimes last well beyond sunset and the
> west coast seems to hang in there until quite late.  On 40 meters you
> will hear stations talk about the band is "going long" in the evening.
> This is when the close in stations start to drop out because the MUF is
> dropping.  Once in a while you will hear them talking about the band is
> "going short" in the morning.  This is when the absorption is starting
> to increase and the more distant stations are fading out. Because the
> distant stations signals go through the ionosphere at a smaller angle,
> they are in the absorption area longer and experience more absorption.
> NVIS signals, on the other hand, go through the D-layer at a very steep,
> near vertical, angle and experience much less absorption.  This
> situation occurs on every one of our HF bands.
>
> Here in South Texas, we are fortunate in that we are close to the
> equator.  The MUF is usually higher near the equator for a variety of
> reasons.  Because of our location, we can easily work South America, the
> South Pacific and South Africa.  Unfortunately we are double hop or more
> from Europe and Asia so we have a more difficult time working them than
> stations on the east and west coasts. Conditions seem to generally be
> best during the spring and fall equinoxes.  Noise levels seem generally
> down and propagation is good in both the northern and southern
> hemispheres.  If you want to work stations in the southern hemisphere,
> these are the best times of the year.  The MUF on cross equatorial paths
> is higher than any other path and we, in South Texas, can use 15, 10 and
> even 6 meters when most of the country thinks these bands are "dead".
> Not only can we work DX on these bands, we can also work other US
> stations via backscatter where both stations point there antennas at a
> common point in the Soth Atlantic or South Pacific and bounce signals
> off this common point.
>
> So in summary, depending on the sunspot number, you should choose your
> band.  The higher the sunspot number, the higher the band.  In the
> morning, look towards the south east, east and north east.  Mid day is
> good any direction and the higher bands to avoid absorption on the lower
> frequencies.  In the evening look towards the north west, west and south
> west.  South is good any time of day and most of the night.  Late at
> night and early morning. 80 meters is the best choice unless you have a
> 40 meter antenna with a low takeoff angle, ie. not a low dipole!
>
> If you have any questions, just send an e-mail.
>
> Kerry
>
>
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