[HCARC] Wideband 80 meter antenna

SARA SANDSTROM kerryk5ks at hughes.net
Tue Feb 11 11:20:38 EST 2014



Gary, 

The impedance of an antenna in a real installation is seldom what is expected.  If the antenna is well above ground and away from metal objects (free space!) , its impedance will be close to its design value .  A temporary installation for NVIS operation is going to be close to the ground, less than a quarter wave, and probably close to conducting/lossy objects.  For 80 meters, a 20 ft center support and 10 ft end supports are probably adequate.  I would put the ends up 10 ft just so animals and people don't run into them.  I think that you will almost certainly need to have an antenna tuner with you no matter what antenna you use.  I doubt that the built in auto tuners will have enough range to be useful.  For 100 W, the MFJ tuners are probably more than adequate.  

I think Bill Tynan suggested a dipole cut for 3600 kc (kHz!) and SSB operation near 3600 and CW/PSK between 3550 and 3600 is a sound idea.  By the way, we can legally operate CW in the phone bands, so we don't need to change to another frequency for CW.  I'm not sure whether PSK is legal in the phone bands, but it might also be.  Since we will only be working among ourselves and not looking for random contacts, operat ion in the traditional segments isn't required.  We just need to be sure that there is an Extra Class operator in each group so we can operate just above 3600 kc. .   

Temporary emergency operation is always unpredictable.  We need to be able to handle anything that comes up.  A simple antenna and a small lightweight tuner is insurance that we'll be able to get a reasonable signal on the air.  Choice of rig is the same thing.  We need to choose simple rugged rigs of the roughly 100 W level and simple reliable laptops for PSK. 

Kerry


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