Topband: EIRP Measurement
bradrehm at gmail.com
Tue Feb 21 09:09:10 PST 2012
I also think this topic is worth addressing, but Bill is probably
right in saying it could gobble all the bandwidth on this reflector.
Maybe someone would be willing to be the moderator of a new reflector.
In the mean time, we should acknowledge that a lot of the work has
already been done by the hams who've been experimenting on 136 kHz.
See http://www.strobbe.eu/on7yd/136ant/#Loops for example.
BTW, the three-antenna method is not considered the best way to make
field strength measurements at these frequencies. Since the field is
magnetic, loops, monopoles, helmholz coils, and other kinds of probes
are normally used.
I wonder how many 160 ops are considering trying the new band. I
wouldn't be surprised if the answer were "very few." Although the new
band is just below AM broadcast frequencies, instead of just above
them, this is the region in which transmitters and antennas begin to
look very different from conventional HF setups. After we've made
substantial investments in time and resources in decent 160m stations,
moving down will present new challenges which may only interest
On Tue, Feb 21, 2012 at 8:49 AM, Bill Cromwell <wrcromwell at gmail.com> wrote:
> On Mon, 2012-02-20 at 19:04 -0700, Tod - ID wrote:
>> In thinking about the measurement of EIRP for the new band it occurred to me that this might be the time for a few folks to think about how we could fabricate a "commonly calibrated" field strength meter. Such a device might well be used on both 160m and the 600 kHz band. By commonly calibrated in mean a device that has an agreed upon standard way to calibrate it that can be done with simple methods. One thing that always intrigued me about the HeathKit products was the fact that they used very simple methods to allow the builder to adjust the device without expensive equipment. Sometimes that meant a special circuit built into the product which was only used for adjusting the device.
>> The important thing is to have a way to assure that when someone measured the same field at the same point with the same type of measurement device they would get the same measurement result. That would allow us to compare measurements between different people even if we did not know the absolute field strength value.
>> An interesting idea might be to make such a field strength meter have an interface to Wi-Fi so that it could be positioned at a remote point and send its readings to one's local network. There are a lot of ways to do that of course, but planning to have it part the device initially would simplify taking measurements. I am sure that there are others who could contribute ideas that eventually could be used to formulate design objectives for such a device. If there was enough interest I can imagine that a single PCB could created and a lot of such devices built to allow us to add to our collection of measurement devices that help us fabricate better antennas and stations.
>> I wonder if I am the only one who thinks this might be a useful TopBand subject.
>> Tod, K0TO
>> UR RST IS ... ... ..9 QSB QSB - hw? BK
> I think this thread will quickly get of hand even though it may be
> applicable on Top Band (and every other band). I took a quick look at
> the QTH.net lists and I didn't see anything resembling
> "instrument(ation)" or "measurement". Are there lists or web groups for
> amateur instrumentation? I will expand my own search and report back
> here if I find anything useful but maybe some list member(s) already
> know where to look.
> The whole point of having standards is so that we can get the same
> results under the same conditions as other people. It should not be any
> more difficult to 'calibrate' to an existing, published standard than
> 'calibrating' to a new 'nonstandard'. There are a lot of different
> approaches to accomplishing that and we should look for them.
> If there is interest we might start a new list to explore the
> Bill KU8H
> UR RST IS ... ... ..9 QSB QSB - hw? BK
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