5/29/09 - Troposhperic Ducting?

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kg7hq Fri, 05/29/2009 - 03:28

We have very warm dry weather creeping up the coast... Could that mean we will have tropo conditions?

Troposheric ducting is one of the more interesting and fun things in Amateur Radio. During ducting ,, it is possible to communicate with stations on the VHF and UHF bands up to over 1000 miles away. That is pretty darn cool for a range of frequencies which normally carry signals upwards to 100 miles.

The spectrum we are focusing is mainly within the VHF (30-300MHz) and UHF (300-3000MHz) bands. This includes amateur radio, Public Service like police, fire and medical dispatches, TV (Both old and new HDTV), FM radio, Aviation.... The list is quite expansive. So even if your a radio scanner enthusiast, there can be some really interesting monitoring.

Let's look at how does this basically works and how can we enjoy it? Lets focus on the word "ducting". Within your house/school/office we use ducts to shuffle warm and cool air around to create circulation. In nature, atmospheric ducts form that can shuffle VHF and UHF radio waves well beyond line of sight range as described above. Tropospheric ducting occurs mostly in the warm weather months of the summer and sometimes in the presence of large storm systems.

Here in the Northwest, the Pacific Northwest VHF Society members use these and other radio wave conditions to enjoy long distance contacts beyond those of our normal daily ragchews and chats. For additional information on this and other VHF/UHF related information, visit their webpage at http://www.pnwvhfs.org/