| |
CX2SA > SATDIG 04.07.09 23:01l 273 Lines 8685 Bytes #999 (0) @ WW
BID : 48323-CX2SA
Read: GUEST
Subj: AMSAT-BB-digest V4 317
Path: IZ3LSV<IK2XDE<PY1AYH<PY1AYH<CX2SA
Sent: 090704/2057Z @:CX2SA.LAV.URY.SA #:48323 [Minas] FBB7.00e $:48323-CX2SA
From: CX2SA@CX2SA.LAV.URY.SA
To : SATDIG@WW
Send AMSAT-BB mailing list submissions to
amsat-bb@xxxxx.xxx
To subscribe or unsubscribe via the World Wide Web, visit
http://amsat.org/mailman/listinfo/amsat-bb
or, via email, send a message with subject or body 'help' to
amsat-bb-request@xxxxx.xxx
You can reach the person managing the list at
amsat-bb-owner@xxxxx.xxx
When replying, please edit your Subject line so it is more specific
than "Re: Contents of AMSAT-BB digest..."
Today's Topics:
1. Re: Antenna Question (R. Chastain)
2. Re: Antenna Question (Jim Jerzycke)
3. Re: The Moon is our Future / antennas (i8cvs)
----------------------------------------------------------------------
Message: 1
Date: Sat, 4 Jul 2009 10:57:42 -0700 (PDT)
From: "R. Chastain" <suenrod@xxxxx.xxx>
Subject: [amsat-bb] Re: Antenna Question
To: amsat-bb@xxxxx.xxx
Message-ID: <964175.1676.qm@xxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=iso-8859-1
Oh My! Somebody else has my warped sence of humor:-) Just ask my
granddaughter. I goof with her all the time with stuff like this.
Like when she asks to get on the computer and I tell her she will break it if
she does:-)
RoD
KD0XX
--- On Sat, 7/4/09, David - KG4ZLB <kg4zlb@xxxxxxxxxx.xxx> wrote:
> From: David - KG4ZLB <kg4zlb@xxxxxxxxxx.xxx>
> Subject: [amsat-bb] Re: Antenna Question
> To: amsat-bb@xxxxx.xxx
> Date: Saturday, July 4, 2009, 11:28 AM
> How can you upload a web page if you
> have your "dog on it" ? Move the
> dog first then try! ;-)
>
> Happy 4th all!
>
> 73
>
> --
> David
> KG4ZLB
> www.kg4zlb.com
>
>
>
>
> Joel Black wrote:
> > Happy Independence Day.
> >
> >
> >
> > Doggonit, I cannot upload to my webpage (something
> else yet to figure
> > out).?
> >
> >
> >
> >???
>
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx.
> Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur
> satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 2
Date: Sat, 4 Jul 2009 11:54:28 -0700 (PDT)
From: Jim Jerzycke <kq6ea@xxxxxxx.xxx>
Subject: [amsat-bb] Re: Antenna Question
To: amsat bb <amsat-bb@xxxxx.xxx>, George Henry <ka3hsw@xxx.xxx>
Message-ID: <237207.42610.qm@xxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=iso-8859-1
The product review is in the August 2004 QST. If you have access to the
reviews page you can find it under the "Q" listings by manufacturer.
Jim? KQ6EA
--- On Sat, 7/4/09, George Henry <ka3hsw@xxx.xxx> wrote:
From: George Henry <ka3hsw@xxx.xxx>
Subject: [amsat-bb] Re: Antenna Question
To: "amsat bb" <amsat-bb@xxxxx.xxx>
Date: Saturday, July 4, 2009, 8:51 AM
Sounds like the "QHTennas", made by N4QH.? Reviewed in QST in 2005, then he
stopped producing them just a few months later.
Near as I could figure out, they are a conventional turnstile design, but
with the 2 dipoles separated by the length of the phasing line, and no
reflector.
George, KA3HSW
----- Original Message -----
From: "Joel Black" <jbblack@xxxxxxx.xxx>
To: <amsat-bb@xxxxx.xxx>
Sent: Saturday, July 04, 2009 9:50 AM
Subject: [amsat-bb] Antenna Question
Happy Independence Day.
Does anyone recognize the following antennas?? I purchased them years
ago and they were part of a system I never installed.? Over the years,
one of the elements has been damaged and, even though I can fix it
myself, I'd like to know who made these.
Doggonit, I cannot upload to my webpage (something else yet to figure
out).? Suffice it to say, my description may not do the antennas
justice.? There are two of them, a 2m and 70cm made out of sched 40
PVC.? They appear to be a "turnstile" type antenna with two aluminum
elements at the top and two at the? bottom 90? out of phase from each
other (top and bottom).? In other words, if looking at a compass, the
top two elements would be at N and S, the bottom two at E and W.? This
is the same on both antennas as they are a matching set.
These antennas were in an old QST, but I have since gotten rid of all
those magazines and cannot find the article online.? Any ideas or
suggestions?
Tnx,
Joel, W4JBB
_______________________________________________
Sent via AMSAT-BB@xxxxx.xxx. Opinions expressed are those of the author.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 3
Date: Sat, 4 Jul 2009 20:27:17 +0200
From: "i8cvs" <domenico.i8cvs@xxx.xx>
Subject: [amsat-bb] Re: The Moon is our Future / antennas
To: "G0MRF David Bowman" <g0mrf@xxx.xxx>, "John B. Stephensen"
<kd6ozh@xxxxxxx.xxx>, "AMSAT-BB" <amsat-bb@xxxxx.xxx>
Message-ID: <006601c9fcd5$1048a640$0201a8c0@xxx.xx>
Content-Type: text/plain; charset="iso-8859-1"
----- Original Message -----
From: <G0MRF@xxx.xxx>
To: <kd6ozh@xxxxxxx.xxx>; <amsat-bb@xxxxx.xxx>
Sent: Saturday, July 04, 2009 1:21 AM
Subject: [amsat-bb] The Moon is our Future / antennas
>
> In a message dated 03/07/2009 20:46:44 GMT Standard Time,
> kd6ozh@xxxxxxx.xxx writes:
>
> Building a prototype that works on Earth for project like this is only a
> few percent of the effort required. Treating it as a radio club project
> won't be effective as people need to sign up for a 5-year project.
>
> Hi all.
>
> John is absolutely right in saying the complexity cannot be easily
> compared to a terrestrial radio project. One other thing that stands an
> almost zero chance of succeeding is a dish antenna that needs to point
> towards the earth. If NASA and the ISS have trouble with moving parts
> on the solar array you can imagine how much more difficult it would
> be on the moon.
>
> However, how about this.
> The problem with the higher bands is power generation / path loss /
> antenna gain. Any higher band like 1.2, 2.4 or 5.8G would need a high
> gain antenna to offset the increased path loss.
>
> But, instead of a conventional steerable dish....with its unreliable
> moving joints...How about an electrically steerable array of patches /
> dipoles / or any other type of antenna element.
>
> But how to 'point' it?
>
> Well. actually I think Tom Clark provided the answer for that with his
> proposal of a few years ago. The principle is this: If you have 2
> arrays. One say on 5.6G uplink and one on 5.8G downlink, then the
> receiving array can electrically look in different directions for a signal
> from the Earth.
> Once the receiver has identified a signal and optimised the RX Antenna,
> the information on the direction of the Earth i.e. the direction of the
> strongest incoming signal can be used to configure the transmit array
> which will then beam a signal back to earth with high ERP.
>
> Directional, high gain, and no moving parts.
>
> Thanks
>
> David G0MRF
Hi David, G0MRF
The following article from G3RUH is a good additional answere to your
message.
http://www.amsat.org/amsat/articles/g3ruh/110.html
I have extracted from it the most important following part:
73" de
i8CVS Domenico
Extracted from G3RUH article "THE EARTH MOVES"
> Moon Downlink
> The maximum total excursion of 9.5? is the same as the beamwidth of a 5
> wavelength diameter dish antenna. This has a gain of some 20 dbi, and
> represents an upper limit for an unsteered Moon-based antenna. However the
> higher the frequency used, the smaller mechanically is the antenna, which
> makes 2.4 or 5.6 GHz a good choice. Five wavelengths is 60 cm and 26 cm
> diameter respectively; quite small.
> For a given TX e.i.r.p., signal strength received at Earth depends only on
> the mechanical size of the RX antenna; frequency is irrelevant [1]. Noise
> level however is not, and S-band (2.4 GHz) is a sensible downlink choice
> because very low noise performance is robustly obtainable "off the shelf".
> An example, 1 watt transmitted from a 20 dbi gain dish on the Moon,
> received on a 1.2m dish at Earth with a system noise temperature of 100K
> results in a signal to noise ratio in 2.4 kHz bandwidth of 10.5 db. (Note
> that frequency matters not). This would support one rather noisy SSB voice
> signal.
> Alternatively it would carry an error-free 2400 bps binary PSK data
> transmission without coding, 9600 bps with modest coding [2].
------------------------------
_______________________________________________
Sent via amsat-bb@xxxxx.xxx. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
http://amsat.org/mailman/listinfo/amsat-bb
End of AMSAT-BB Digest, Vol 4, Issue 317
****************************************
Read previous mail | Read next mail
| |
