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Hi Jeff,
Yes, we’ve been planning for Field Day for a while and have selected a site. We have a weekly webex going on Thursday evenings to cover several projects including Field Day, NEAR-Fest, and HAB-3. I’ll add you to that call.
The new DXpedition mode should make FT8 really active for Field Day this year. In addition to running it on the 6 station, we are planning to have 3 HF digital stations in our setup this year (40m, 20m, 15m/10m/80m). The HF stations will likely all be SDR based using Flex radios.
Hi Jamey,
Thanks! Can you bring your Tech book on Friday when we go to BGHS? We might find a good home for it there as a result of our meeting that day.
Folks,
The website may show the PS2B kit as out of stock at the moment. Its OK to order it anyway as the kits will ship no later than January 22 and you will receive them in time for our February Tech Night Kit Build on February 13th.
Hi Jay,
Yes, the mobile antenna system that we’ll be talking about is similar to the one that you are working with in your portable setup. Lets also plan to take a little side trip during tech night and talk about the radial questions as well.
Hi Jay,
The basic choice on the radial situation is one of elevated radials vs. radials on the ground. If you choose elevated radials, then cutting 2 minimum for each band would be the way to go. This can obviously get out of hand if more than 2-3 bands are involved.
With radials on the ground, you will typically want a certain number that are all equal length. In this scenario, you are trying to make the ground behave as a conducting surface. The best overall length depends up how many radials you can lay down. See –
http://www.w0btu.com/Optimum_number_of_ground_radials_vs_radial_length.html
If you only want to do one band, I’d suggest 3-4 elevated radials cut to the right length(1/4 WL) for the band you are on.
If you want a multiband setup, I’d go with perhaps 4-8 radials on the ground cut to 1/4 wavelength or less for the lowest band that you want to operate on. Note that the table in the link above suggests shorter ground radials for low numbers. My experience is that this is good advice if you are in the range of 8-32 radials. Setups with small numbers of ground radials might need longer ones to get the antenna to tune up properly (but never more than 1/4 WL unless you have more than 90).
Given your goal to setup portable on multiple bands, I think I’d recommend the second scenario (4-8 ground radials) as the practical one for you. If you also plan to setup your antenna at your Home QTH, you could either do either elevated radials or radials on the ground with say 16-32 buried radials centered at the location where you plan to setup your antenna for operation from your home qth.
There are obviously lots of choices between these two. Also, performance for any such installation will depend upon the conductivity of the ground at the actual site where the antenna is installed.
Note that in Patrick’s situation, his radial system is essentially an elevated one and radials of 1/4 WL are needed.
Hi Jay,
FB on the portable HF setup you are building for demos with the Scouts!
Your initial thought was probably the right one – the counterpoise wires should be 1/4 wavelength on the lowest frequency that you will be using. You should try for 3 – 4 wires if you can handle the space requirement, 2 minimum. It will be best to keep them slightly elevated if you can find a way to do that to limit ground losses but they will also work if placed on the ground.
It is probably best to try to setup the entire system in see what it wants in terms of radials. The radiator on your antenna is pretty short for 40m and it looks like it uses a coil/base loading to overcome this. There are scenarios where shorter radials and a greater use of the base loading effect might give a better match. Only way to know if this is the case is to try it.
I hope this helps. Happy to talk with you live some more about all of this. Looks like we may be getting together for lunch sometime soon!
We will have our portable satellite station up as well. It looks like one of the best days for satellite ops in awhile with many high angle passes. Check out the attached PDF for details.
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