Why the 80m Band?

The Alberta Public Service Net (APSN) is held in the 80m Band.  Below is some band information you may find useful.  This information will help the newer operator make good use of this band in addition to making your participation in APSN activities more enjoyable.

The 80m Band and YOU !

The 80m band covers 3500 kHz to 4000 kHz (IARU Region 2).  The upper portion of the band which is generally used for phone (voice) is sometimes referred to as 75 meters.  In Europe 75m is a shortwave broadcast band with a number of national radio services operating between 3900 kHz and 4000 kHz.
 
Because of high D layer absorption that exists during daylight hours, the 80m band lends itself to good evening, night, and morning communications.  Generally, only local communications are suitable during daylight hours.  This band is popular for ‘regional’ communications from the late afternoon through night time hours.  During the evening, night, and morning the band is quite reliable for short to medium distance communication, with average distances ranging from very local contacts out to a distance of 1,500 km or more depending on atmospheric and ionospheric conditions.  Global coverage can be achieved during the late fall and winter by a station using modest power and common antennas.  It should be noted high background noise on 80 meters, especially when combined with higher ionospheric absorption, causes stations with higher effective radiated power to have a decided advantage in long distance communications. 

Somewhat related to the items above, the 80m band encounters season variability.  In the northern hemisphere the band can be quite enjoyable during the longer fall, winter, and spring evenings.  
 
Antennas at this frequency can be large.  A quarter-wave vertical is approximately 65 feet (20 meters) high. Erecting large antennas and ensuring they radiate sufficient power at low angles are two of the challenges facing radio operators wishing to communicate over long distances. (i.e. North America to Europe)  Radio Operators interested in 'regional' or 'local' communication can obtain good performance by using low wire antennas, dipoles, inverted vee, EFHW, or loops.  Horizontally polarized antennas closer than a quarter-wave to earth generally produce high angle radiation patterns which are useful for short distance propagation.  (i.e. Near Vertical Incidence Skywave – NVIS)   Although better antenna yield more reliable performance, it should be noted even a modest wire antenna a few feet off the ground is often enough to reliably check into the APSN from anywhere in Western Canada.   The APSN tries to accommodate the 'mobile' or 'low power' operator by taking check-ins for this group at in the beginning of the net.
 
Similar to all bands the 80m band is unique.  Urban noise, noise from thunderstorms, along with other man-made sources may be encountered.  Solutions to this may include:

• Engage the radio attenuator
• Lower the RF gain control
• Common mode choke or other interference reducing techniques/devices
• A dedicated ‘receive only’ antenna (Loops, beverage or other low noise antennas can be used providing a lower noise floor while maintaining the desired incoming signal)
• Use our province wide network of KiwiSDR receivers (The KiwiSDR is used for reception via smartphone or computer and the operators station is used for transmission)

 
Mobile operation is possible.  It should be noted the relatively short length of practical mobile antennas (usually less than 10 feet / 3 meters) compared to a quarter-wave antenna results in the need for significant inductive loading to achieve resonance. Since short antennas have very low radiation resistance, their efficiency is typically below 10%. Additionally, the large inductance of the loading coil creates an antenna system with an extremely narrow bandwidth (high Q).

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Seasonal Changes and Band Reliability

The 80m band is susceptible to changes at various times of the year.  As mentioned above the band offers better performance during evening, night, and early morning hours.  As such, the band also offers better conditions in the winter.   While the band is still very usable throughout the summer months, the band offers even better performance and a lower noise floor during the darker winter months.