I have been a Technician for some 17 years, always intending to get my General license and get on the air on the High Frequency (HF) bands, but other things always seemed to get in the way. In February I finally took the General exam, and passed. I acquired a rig, a Yaesu FT 450D, and a power supply.
The Mrs and I had several discussions about antennas. She didn't want a permanent antenna showing outside. Apparently that is a common reaction by people who don't mess with radios. So, I ultimately acquired an Alpha Antenna Pro Master Complete 80 - 10. The 80 and 10 refer to the band, with 80 meters being 3.500 MHz to 4.000 MHz. The amateur radio bands can be found here. Besides being portable, so that it doesn't need to be up all the time, it has a Near Vertical Incident Skywave (NVIS) element. The NVIS element is critical to being able to listen to and respond to the local section nets for the Nation Traffic System. If you wonder why the federal government allocates valuable space in the radio wave spectrum to amateur radio, the National Traffic System (NTS) is one major reason. When disaster strikes, often normal communications go down. The National Traffic System often is the only thing providing health and welfare communications out of the area.
The vertical antenna worked great for long distance, as I quickly picked up conversations with people in Texas, Iowa, Georgia and Virginia. But I could barely understand local net traffic, and they could barely understand me. I talked to Steve at Alpha Antenna, and got some good tips, which help some. Still, this was supposed to be a "tactical" antenna. Hmmm.
Some research led me to the idea of a low dipole tuned to the local NTS frequencies. Normally dipoles should be hung 1/2 of a wave length high, which in the case of 80 meters is somewhere around 150 feet in t air. But, if the are hung only several feet, they become excellent "cloud burners" sending the signal straight up, to be reflected straight back down and enabling local communication.
I managed to splice some wire onto a 40 meter dipole I already had using wire nuts, and used a couple of ceramic end insulators, also just laying around, to build an 80 meter dipole. Now the general formula for a dipole length in feet is 468/frequency in MHz. But for low dipoles, the actual numbers approach 450/frequency. Frustrating though it was, I did get it tuned to the actual frequency on the 80 meter band. Suddenly I could hear everyone checking into the nets. Not only that, but there is actually a lot of activity that takes place locally, within a couple hundred miles, on 80 meters that I was not getting from the vertical.
This week we have had a frog strangler of a rain event. I took down the vertical because of high winds and possible lightning. Interestingly, when I got on this morning to check into the morning traffic net, my antenna was again detuned! It actually appears to have moved downward by around 100 Hz. It was enough on that band to keep me from checking in. It seems this is normal too.
After years of the reliability of communications on the Very High Frequency (VHF) bands it is a challenge to reliably communicate on the HF bands. On the other hand, the VHF frequencies are short range in nature, whereas the HF bands allow world wide communication. Of course, in this day and age in which anyone can make a telephone call to the other side of the world, at any time, it may seem...well...stupid to be trying to communicate by such a hit and miss technology. But just remember when disaster strikes...sometimes the only thing left is your friendly local ham.
The Mariana Trench
28 minutes ago