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

Re: SETI Yet another hair-brained-antenna-idea?
Sun, 6 Sep 1998 22:38:02 EDT

In a message dated 9/6/98 6:19:22 PM Pacific Daylight Time,

On Sun, 6 Sep 1998 17:04:29 EDT writes:
>In a message dated 9/6/98 1:43:26 PM Pacific Daylight Time,
><< Subj: SETI Yet another hair-brained-antenna-idea?
> Date: 9/6/98 1:43:26 PM Pacific Daylight Time
> From:
> Sender:
> To:,
> CC:,
> Yesterday, Rich wrote:
> < 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.
> Chip N1IR wrote:
> *Uhhh. Which one?
> Rich replies:
> ~ Sorry, I've been reading so many papers and abstracts lately
> I can't recall.. It may have been a list on a SETI web site. If you
> really want to know, I'll try to find it and post it..
>**Doesn't sound familiar...might be a Russian effort with very broad
>bandwidth. But that was a dipole ARRAY.

Rich Relies:
Now I remember, it was at:

Yes, you are right sir.. I was wrong about the frequency..
It was Russian.. I didn't read the whole list,
but there may have been dipole arrays too..

DATE: 1968 - 1982
SEARCH FREQ.(MHz): 30 CM, 16 CM, 8 CM and 3 CM
COMMENTS: Search over all sky visible by single dipole.

^OK; THAT one. The reason this is even listed is mostly political. PLUS the
fact that it was a broad band approach. The Russians were really into this;
think CTA 102 debacle.

> < 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.
> ~ Yes I agree. It's not a good compromise. It would be far better if
>we all owned 6 meter dishes. (Better for what most of us want to do)..
>** I would be much happier if you all owned 60M dishes:-) from the
>figure of merit standpoint.

Too narrow.. Need width.. See more sky..

^I can see I'm going to have to put something in JBIS on the spatial figure of
merit... I'm not insulting you; just saying that the FOM stuff needs to be
clarified in publication.

(XYL is now tapping out the words "rain tomorrow, mow lawn before dark"
morse code).. Be back in 72 minutes..

^ At least ur wife learned morse code! Mine can copy but not send. 160 IQ and
can't do Morse:-(

> < 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.
> ~I agree, a helix is not a dipole. But a helix with a small amount
>of gain would be my choice, even if it wouldn't cover the whole sky at
> (At least a helix pointed skyward wouldn't see as much ground noise).
> ~I use the term 'helix' because it's shorter. When I last spoke with
> John, he didn't say "axial mode Kraus helix". He just said "Helix".
>** That's because he didn't want to confuse you with the two other
>modes. Your (spring) stubby is a normal (Wheeler) mode helix.

I don't agree, even if he is an old timer, he still is very sharp.

^He most certainly is.

He knows I'm project tech at the MIT Lincoln Lab antenna test range,
that I've been working on Helix antennas and reading his books..

^ Hmmm. Ask me about fractal helices off line. In 1998 ACES Proceedings...

>So if it's okay with the him, it's okay with me.
> (Maybe I should be more careful, I hear Uda killed himself after Yagi
> got all the credit)..
>** The pioneer often gets shafted..

Uda had lots of other problems too.. Depression I think..

^If kava had been around, might be the UDA-Yagi antenna.

clip-clip-clip. I'm beat..

> < 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.
> ~True, but not too outrageous if the range was short.
>** If the range is short, then statistically you are demanding that
>the density of ET;s is so high that ETI is effectively an infestation in

>the galaxy....

You know, maybe you're on to something. Maybe this is an assumption
we should make for development of a new search stratagem..?
If we are going to make some assumptions, we shouldn't always be

^Occam's razor my friend...

> < 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
> increased. (Still maintaining full sky coverage by using assigned
> * But you still won't search the globe by keeping everyone in the
>same to speak.
> ~ If nothing else, some of these low gain stations may eventually
> upgrade to BUDs and move themselves off the block a few yl...
>** Uhh..why?

Some folks will do almost anything in the fight against boredom.
Like SWLing, It's only a hobby for most of us..
My question is, why watch baseball on TV? It's a heck of a lot more
fun to play a game of catch.. (I know, I know.. Someone's going to
break a home run record)..

^ Once again I fear I am pictured as the SETI party pooper. I have genuine
respect for the 'gung ho' attitude you guys have. Its the equipment that's the
problem(in terms of the FOM). I'm not 'blaming your tools' Just saying they
are the wrong ones.
> < 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
> < 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.
> ~ I can think of one reason right off hand. If an ETI probe studying
> earth knew we were listening on 1420.4056 Mhz, and wanted to be
> Of course, a probe might not want to signal us at all..
> SETI is like fishing, you may never get a bite or you may get yanked
> out of the boat..
>** IF they already KNEW this then they presumably would have other,
>more efficient ways of communicating.

What kinds of ways? I'm interested in any ideas you might want to put

^ Like answering Allan Tough's internet invitation;-).

clip-clip-clip again..

> <Or maybe LDEs are feelers they put out to see what our reaction
>will be..?.
>**LDE's are plasma phenomena and the amateur reports on this (such as
>dates; times; and so on) are rife with errors. I know this. See Feb 78
>for a great idea obviated by the wrong data (admitted later) published

Sounds like UFO reports.. I would be hard pressed to dig up my novice
log and find the data on the 15m LDEs I heard in 1969.. It's certainly
is a strange phenomenon. The LDEs heard by EMEers this summer
is the most recent case I've heard of..

^ What?! I want details.Please!

A lot of the old timers I've
to over the years have heard LDEs. I'm not so sure that 'plasma' between
here and the moon could be the cause of those delays that take
longer than the normal EME round trip.. I'll do more research..


>** Ideas are wonderful things. But being SCIENTIFIC demands some
>sifting. This could have been a fairly simple exercise to work out
>extrapolating to implications.

Very true. I'm sorry that I wasted my youth goofing off instead of
the basics..

^Yeh, but u had more fun:-)

But after teaching for 10 years, I just can't stand to be
in a
class room unless the instructor knows what he's doing. Around here
it's much more likely that your instructor is lacking in basic teaching
or he just plain don't give a dam about the job..

> ~Thanks for the F minus. I just hope my blurb was a little better
> reading than the spinning swimming pool full of Jello with BBs (or
>** Shall I grade? I would say an A-; it indicates that you are
>thinking but need just a bit more work to get there...

Wow, thanks.. I really mean it..

^So did I. Most of the 'pro' SETI people haven't said anything useful in 15
years...or thought about much of anything.

> * The Kardashev 1964 paper considers isotropic transmissions and
>hence the outrageously high powers need for ''Type I,II etc" civs.
> ~Of course everyone on the list is well aware of Kardashev's 64
>(Astron) paper.
^ Well, I've got it. From a 1974 photocopy copy I made. Guess I could xerox if
anyone long as I don't get lots of requests.

>** Are they --really-- or as highly derivative extrapolations?

No not really. I was making a dumb joke.. Does "highly derivative
mean guessing about things unknown?

^ I mean that its always referred to, even by people who haven't read it.

> However, that Type III stuff seems really unlikely.. (Harnessing the
> energy of a whole galaxy? 4E37 Watts?). Come on already...
>** Kinda goofy.:-)
> Anyhow, from what I've read Stephenson's 1981 paper shows a more
> reasonable scenario.. And 'isotropic'.. I just don't get it. Why would
>want to waste 99.99% of their RF?
>** You are asking to waste may 60%....
>If I was them, I would get myself a dish. (or a Helix)..
>**Large for the former; LONG for the ladder:-)
>* *Regards,
> **Chip N1IR
> ~Thank you Chip, for expertly pointing out the negative aspects of
>the low-gain idea. Many of us on the list are not experts (especially
me) and need
>to be reminded of what mother nature will permit. However, this is a
> where ideas can be aired, no matter how far-fetched they sound.
>** I didn't say 'don't air it' What I said was think about whether
>this made sense before taking the next step (which you described in some


Sorry about the extra detail.. That's what comes of reading too much
Tom Clancy stuff..

^ When he starts talking about fractal antennas then I'll probably get into a
Clancy kick;-).

>I just hope that others won't be reluctant to post after seeing my
poor grade..
> (But please no more Jelly pools).. :-)
>**An A- is a poor grade?

Nope, it's very good for me.. And rare too..

^ Don't see why...

> ~73, RIch NJ1A
>*Chip N1IR

It's been real fun, thanks.. Rich <>



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