How can you arrange 16 receivers with an homebrew antenna system? I'd like to have three antennas or no more than four ideally. I'm not interested in direction finding, need low profile for neighborhood, and to work in the space uhf/vhf frequency range.

Is it really necessary to do much more than hook up the wires, or must they be electrically isolated somehow and therefore need a fancy design?

If it is easier than drawing diagrams, can you otherwise recommend a low profile space/sat antenna system that might function well with multiple receivers?

'notyeti'

This is a health physics project. Everything is pointed up at one end and a data logger at the other end. Basically everyday it just takes a reading, or space weather ob, and I'm just a hobbyist more familiar with the data logger and where to find local health stats. I guess it just points up and has to keep track of space weather for the next forty years. Any suggestions or links to or from real health physicists would be wildly appreciated.

I have no idea how your second post in this thread relates to your
first one, but...

If you want any sort of sensitivity for 16 receivers tied to the same
antenna, especially in the UHF range (where even with a single
receiver, the receiver noise is likely going to dominate over the noise
the antenna picks up), you should put a decent preamp on the antenna.
The power from the antenna, best case, will divide among the receivers.
In the real world, you'll loose some additional power in the system
you use to split the power among the receivers. Just tying them all
together is about worst case. It would be reasonable to look for a
preamp with perhaps 15dB gain, and in fact you could find a
distribution preamp that will divide the signal for you and give you
more-or-less isolated outputs. One way they do it is to have an input
amplifier, say a 4-way splitter, and then another amplifier on each of
those splitter outputs, each of those driving another 4-way splitter.
That generally gives better performance with respect to distortion and
noise.

If you're only dealing with large signals, you could try just a simple
splitter arrangement, but don't expect good sensitivity in the
recievers.

Cheers,
Tom

Thanks Tom,

I do have almost as many splitters and amps as receivers. You call them scanner receivers, but since some of them are computer controlled, they ultimately are good for all kinds of natural sampling experiments. So as you suggest, I'll start with the most simple arrangement and work backward until the receivers start to work well per experiment. I have done electronics, device, and ac/dc circuit analysis before, but nothing in radio frequency space. I knew there was a plan! Thanks Tom.

I worked with nws/asos equipment once and so want to build a hobby "instrument" that could record anything, space weather wise, in the radio frequency realm, that might -or not- wash over the city and trigger health problems. It would systematically record as "large a signal" then as regular weather observations detect with traditional instruments and from a fixed position.

A big smile,
notyeti

"notyeti" wrote in message
...

How can you arrange 16 receivers with an homebrew antenna system? I'd
like to have three antennas or no more than four ideally. I'm not
interested in direction finding, need low profile for neighborhood, and
to work in the space uhf/vhf frequency range.

Is it really necessary to do much more than hook up the wires, or must
they be electrically isolated somehow and therefore need a fancy
design?

If it is easier than drawing diagrams, can you otherwise recommend a
low profile space/sat antenna system that might function well with
multiple receivers?

Yes, they absolutely must be isolated or you upset the impedance of the
system. Isolation is done with splitters or directional coupler taps.
T-connectors are often a problem, as they tend to encourage reflections in
the cables.

I presume that you have a low-noise amp at the antenna that sets the noise
figure for the system. Thus, all you have is a divider problem and many,
many amplifier/splitters that are flat from 50 - 1000 MHz are available for
home and small apartment TV systems. If you need to get into L-band, there
are booster amps for SAT-TV that do well from 950-2250 MHz.

I googled for 8 way splitter amplifier low noise TV and got this
among the thousands:

http://www.smarthome.com/7750-8.html

not saying it's the best ... it's just one of the many.

Good luck.

Hi Sal,

I appreciate your suggestion. I am looking for radio interference more than anything. It would just be enough to note that there was interference, and its local level, on certain frequencies. It would be good to have a good clean signal per receiver to establish a base line. Some of the 'wx' only affects certain operating frequencies which makes it easy to find. You can see some of the more exotic stuff at www.sec.noaa.gov which is "right down the street." The only difference I'm coordinating it with crime and health information instead of terrestial communications. "Right up the street" another amateur discovered that lightning goes upward, in a relative handful of configurations. My experiment is not so real time. I do appreciate your idea however and plan a grounded wall box with a few of those sort amps inside. Thanks Sal. Stay dry!

notyeti