archive: Re: SETI Yet another hair-brained-antenna-idea?

Re: SETI Yet another hair-brained-antenna-idea?

Fractenna@aol.com
Sun, 6 Sep 1998 11:31:54 EDT

In a message dated 9/6/98 8:16:18 AM Pacific Daylight Time, rtyndall@juno.com
writes:

<< Greetings my fellow Setizens,
I recently read a paper somewhere that included a list of past SETI
searches.
As I recall, one of those searches was done with a simple dipole
on 1420 Mhz.

*Uhhh. Which one?

Now that I've had some time to think about it, it may not be such
a bad idea.

* It is not a good idea.

A dipole (or a 2 turn LH Helix) could cover a lot of the sky.

*That's not a dipole; its a axial mode Kraus helix with quasi-hemi coverage.

A hand held GPS receiver with a small antenna can easily hear
weak GPS signals from very high orbits.. (Ranges of 20,000
to 25,000 km). (My BUD could likely hear a GPS in Lunar orbit).

*yes... but not relevant.

My Points:
We don't know the direction of the incoming signal. (a prime
reason for the Argus project). We don't know how strong the
signal will be.. It could be very weak or very strong..
Maybe a low gain antenna could hear it.

* The transmitted power you would need would be outrageously large.

Benefit #1:
Those folks who can't install a BUD could increase their participation
in SETI work. If hundreds of coordinated Non-BUD searchers were to take
part,
a few dB of gain could be added to each site as their numbers increased.
(Still maintaining full sky coverage by using assigned declinations).

* But you still won't search the globe by keeping everyone in the same
block...so to speak.

Benefit #2:
In the event of a very strong short term ETI signal, a few wide field
SETI
stations around the world might record the hit at the same time.
That would definitely put ARGUS (everyone) on red alert..

Benefit #3.
Although less sensitive, continuous full sky coverage might give us
a better chance of detecting any Probes (see note) in the local solar
system area.

* I don't follow this; nor the reason why such probes would use microwave
signalling to us.

In conclusion:
One point we have all heard, 'Any coverage is better than none'. If a
signal was
very strong and of short duration, chances of hearing it with a few dozen
3 meter
dishes is small. A few dozen wide field antennas (in the mix) might
give us better odds.
If the wide field participants were well coordinated, (good clocks & LOs)
their daily
data could be collected into one data base and analyzed for common noise
peaks & etc.
(Who knows what we might find)..?..

*Exceedingly unlikely you will find anything but interference.

Note:
Some Probe theory. Some have estimated that during the next 10 Million
years, probes
(or manned star ships) from Earth could travel to most parts of the Milky
Way. That is,
if they can fly at 0.1 the speed of light. (Plus or minus a few million
years for variations in
propulsion technology)..

Paradoxically speaking, during in the last 10 Billion years, many
(thousands?) of ET
civilizations should have, 'Been there, done that'. As the man said
"Where's ETI"?
They should be here already! So the point is, maybe they are. Maybe
there are some
robotic Probes sitting out there in near-earth space scanning the Earth
for signs
of intelligence. ;-)
Why have they kept silent? That's a good question, maybe they're on a
schedule.
Maybe they only call us for 3 weeks every 15 years.. Or maybe LDEs are
feelers
they put out to see what our reaction will be..?. (Did you notice the
word 'maybe'
appears at random in the above text)? This could go on for pages & ages..
Time to go, 73 Rich <>

*Richard, you have failed to compare the spatial figure of merit for various
low gain/ high gain systems,and looked for the dependence on transmitted power
(in the scenario you describe). I will give you a hint: the FOM goes as the
SQUARE ROOT of the transmitted power (among other factors)...that's not cause
for optimism unfortunately.

* The Kardashev 1964 paper considers isotropic transmissions and hence the
outrageously high powers need for ''Type I,II etc" civs.

*Regards,

*Chip N1IR

Richard Tyndall NJ1A Woburn, MA. USA
RTyndall@juno.com or nj1a@erols.com
ARGUS Observatory FN42jl

-
-
-
-
-



_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]


----------------------- Headers --------------------------------
Return-Path: <owner-seti@lists.sni.net>
Received: from rly-zb04.mx.aol.com (rly-zb04.mail.aol.com [172.31.41.4]) by
air-zb01.mail.aol.com (v49.1) with SMTP; Sun, 06 Sep 1998 11:16:13 -0400
Received: from lists.sni.net (lists.sni.net [199.117.27.1])
by rly-zb04.mx.aol.com (8.8.8/8.8.5/AOL-4.0.0)
with ESMTP id LAA29512;
Sun, 6 Sep 1998 11:15:55 -0400 (EDT)
Received: (from majordo@localhost)
by lists.sni.net (8.8.5/8.8.5) id JAA21218
for seti-include; Sun, 6 Sep 1998 09:04:46 -0600 (MDT)
Received: from relay-qwest.sni.net (relay-qwest.sni.net [199.117.162.17])
by lists.sni.net (8.8.5/8.8.5) with ESMTP id JAA21214
for <seti-list@lists.csn.net> Sun, 6 Sep 1998 09:04:44 -0600 (MDT)
Received: from lynx.sni.net (bobcat.sni.net [199.117.160.5])
by relay-qwest.sni.net (8.8.8/8.8.8) with ESMTP id JAA13165
for <seti-list@lists.csn.net> mail_from <bcutter@csn.net>
Sun, 6 Sep 1998 09:04:14 -0600
Received: from x7.boston.juno.com (x7.boston.juno.com [205.231.100.24])
by lynx.sni.net (8.8.5/8.8.5) with ESMTP id JAA06099
for <seti@sni.net> mail_from <rtyndall@juno.com>
Sun, 6 Sep 1998 09:04:13 -0600 (MDT)
From: rtyndall@juno.com
Received: (from rtyndall@juno.com)
by x7.boston.juno.com (queuemail) id DNGK6QQG; Sun, 06 Sep 1998 11:03:33 EDT
To: seti@sni.net, argus@seti1.setileague.org
Date: Sun, 6 Sep 1998 11:02:10 EDT
Subject: SETI Yet another hair-brained-antenna-idea?
Message-ID: <19980906.110211.11622.0.RTyndall@juno.com>
X-Mailer: Juno 1.49
X-Juno-Line-Breaks: 0,2-20,22-26,28-33,35-37,39,41,43,45,47-50,52,54,
56-58,60,62,64,66-67,69,71,73-89
Sender: owner-seti@lists.sni.net
Precedence: bulk

>>