• Gabriel Zacchai

DIY Field deployable dual band communication system

Cellular communication bottlenecked in the aftermath of some unimaginable cataclysm? Zombies breathing down your neck? Need to get an idea what's going on two states away? Just need a reason to go for a damn hike on an ordinary beautiful day?

This dual band YAGI beam antenna ($70) concentrates all the power you've got in one direction, as opposed to a vertical base station or rubber duck. Weighing in at 13 lbs, if you put this rig on your back for that afternoon hike, when you reach the summit, your VHF/UHF line-of-sight transmission opportunities are exponentially increased.

Connected by a 5 foot jumper of RG8x coax cable ($15), a 25W Anytone 778 mobile dual band radio ($120) is powered by a 12VDC 7AH battery ($20) which is supplemented by a 7W solar panel ($20), contained in a sturdy

and water/impact resistant Pelican case ($30).

There is also space within the kit for a handheld 5w Baofeng that can be connected to the YAGI and used as a backup, or taken to other locations and used with a whip antenna to communicate back to the base station.

Depending on weather and VHF propagation conditions, at an altitude of 1,300 feet, this 25w transceivers' usual sea level simplex transmitting range of approximately 30 miles multiplies to around 150.. The ability to utilize duplexing repeaters at the edge of that range can then extend that range to an additional 100 plus miles from the repeater point. These ranges are general and can vary greatly depending on a number of environmental factors, but a good example of the ability of a low power VHF signal to travel unobstructed is the International Space Station. The ISS is in orbit 254 miles above the earth, but it is fairly easy to make contact with it when it is overhead (direct line of sight) even with a handheld 5w transceiver and a directional antenna.

Utilization of the high frequency wavelengths (with a proper HF transceiver) by stringing up a homemade wire dipole antenna into some trees, with favorable atmospheric propagation can even increase communication distances across continents.

HF communication and DIY antenna building require some additional skill and licensing beyond the entry level of ham radio. The process of studying for and obtaining that license is, in my opinion, the best way to learn the skills needed to explore HF communications. Additionally, through licensing, the ham radio community rapidly becomes another level of emergency preparedness that the 'lone wolf' prepper will never gain access to.

[ *Note: This post was created in January/February in the state of Maine. Hiking up a mountain at best would be extremely unpleasant, and at worst could end your life. Stay tuned for updated pictures and testing at the first thermal opportunity that presents itself.]

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© 2023 by Gabriel Zacchai