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July 2004
Very Different Conditions
on the VHF Bands
The first and second
halves of this past July presented much different conditions on the VHF
bands. From strong sporadic-E activity on 6 meters and a fantastic 2-meter
sporadic-E opening early in the month, to high geomagnetic activity
resulting in aurora activity later in the month, WB2AMU presents
observations and takes a look at some of the physical mechanisms that were
involved.
By Ken Neubeck,* WB2AMU |
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T he arrival of summer always heightens the
expectation level of VHF operators in terms of potential sporadic-E (Es)
activity, particularly double-hop Es on 6 meters. July is usually the
month focused upon, considering its potential for good conditions and the
availability of VHF operators who are on vacation and visiting either rare
grids or new countries.
As in previous years of strong sporadic-E activity on 6 meters, July 2004
began in a similar fashion. In addition, a fantastic 2-meter sporadic-E
opening occurred. However, the last half of the month presented high
geomagnetic activity, which resulted in completely different propagation
in the form of aurora activity. This article will summarize some
observations and take an in-depth look at some of the physical mechanisms
that were involved in these propagation conditions.
Sporadic-E in early July
In July 2003, many VHF operators in the Northern Hemisphere experienced
exceptional sporadic-E conditions almost on a daily basis. Despite the
decline in F2 activity during the previous winter months, a fair amount of
DX was present. July 2004 began in the same fashion.
Beginning on July 3rd, the 6-meter band was open to Europe just before 11
AM EST. At that time at my location in grid FN30, I worked both EH7KW in
Spain and a special prefix for Portugal, CT14HZE. Finally, after very few
transoceanic openings during the month of June, there was a decent opening
from my area into Europe.
During the July 4th holiday the band was open into the southern states
from my location, and a DX station, C6AGN, was heard running pile-ups.
FP/N9OT was also running pile-ups from Miquellen Island. These conditions
were expected at this time of year.
On July 5th things really got interesting. Again, the band was open to the
south during the late morning hours. I had dropped off my wife at the
mall, and I found a suitable tree in the parking lot to hang my portable
2-element Yagi for the purpose of feeding my Yaesu FT-100 in the car. I
worked a handful of stations in the Georgia, North Carolina, and Tennessee
areas. No doubt I could have worked some of these stations using my
1/4-wave vertical, but the Yagi gave a decent punch to the signal. Hanging
it in a tree was worth the effort.
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