QRZ! Ham Radio 4/QRZ Ham Radio Callsign Database - Volume 4.iso/digests/antenna/940048.txt

Internet Message Format | 1994-11-13 | 8KB

Date: Sat, 26 Feb 94 04:30:12 PST
From: Ham-Ant Mailing List and Newsgroup <[e-mail]>
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Subject: Ham-Ant Digest V94 #48
To: Ham-Ant


Ham-Ant Digest              Sat, 26 Feb 94       Volume 94 : Issue   48

Today's Topics:
                            160 M on G5RV
                           A crazy antenna
                         A question (2 msgs)
                        Design of Yagi Antenna
                        Simple Signal Question

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Archives of past issues of the Ham-Ant Digest are available
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We trust that readers are intelligent enough to realize that all text
herein consists of personal comments and does not represent the official
policies or positions of any party.  Your mileage may vary.  So there.
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Date: Fri, 25 Feb 1994 03:43:41 GMT
From: unogate!news.service.uci.edu!usc!elroy.jpl.nasa.gov!swrinde!cs.utexas.edu!howland.reston.ans.net!europa.eng.gtefsd.com!news.msfc.nasa.gov!sol.ctr.columbia.edu![e-mail]
Subject: 160 M on G5RV
To: [e-mail]

regular
Keywords: G5RV


Has anyone figured out how much wire you need to add to a regular
G5RV to tune it to 160 M? Mine is 102' with the 30' of 450 ohm
ladder line and I normally run it on 75 and 40 M through a MFJ-949D
tuner. I've thought of putting up a dipole for 160 but thought that
someone may have done some testing with the addition to a normal
G5RV and maybe(?) not experienced much difference on other bands
while accessing 160. I suspect that the answer is the addition of
something over 60' on each end to get it to tune.
Thanks in advance.
--

73 de Ed Engel   N7UQZ
Internet: [e-mail]

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Date: Fri, 25 Feb 1994 15:34:12 GMT
From: mvb.saic.com!unogate!news.service.uci.edu!usc!howland.reston.ans.net!europa.eng.gtefsd.com!library.ucla.edu!csulb.edu!csus.edu!netcom.com!netcomsv!bongo![e-mail]
Subject: A crazy antenna
To: [e-mail]

In article <2kkj4d$[e-mail]> [e-mail] (Elendir) writes:
> It's just an attempt to design an antenna which would receive all
>polarizations

    This type of antenna os called "Circularly polarised". There
are several designs around.

--
Julian Macassey, N6ARE  [e-mail] Voice: [phone]
Paper Mail: Apt 225, 975 Hancock Ave, West Hollywood, California 90069-4074

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Date: Fri, 25 Feb 1994 15:34:18 GMT
From: mvb.saic.com!unogate!news.service.uci.edu!usc!elroy.jpl.nasa.gov!swrinde!emory!rsiatl!ke4zv![e-mail]
Subject: A question
To: [e-mail]

In article <2kj3e1$[e-mail]> [e-mail] (John Derry) writes:
>If I am given two choices as follows on some inexpensive coax at a hamfest
>fleamarket which do I buyY
>
>The cables are identical in every way, same markings, price, length, etc.
>
>At 144 MHz, when I measure the SWR with an accurate SWR meter one cable
>gives a SWR = 10 and the other gives SWR = 6.  (SWR being measured at one
>end and the other end open (Or shorted.)
>
>Which cable should I buy?

That's a softball question. Obviously buy the one with the higher SWR.
For the reasons, search the archives for my treatise entitled "SWR is
your friend".

Gary

--
Gary Coffman KE4ZV          |    You make it,     | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems |    we break it.     | uunet!rsiatl!ke4zv!gary
534 Shannon Way             |    Guaranteed!      | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244     |                     |

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Date: Fri, 25 Feb 1994 19:01:11 GMT
From: mvb.saic.com!unogate!news.service.uci.edu!usc!elroy.jpl.nasa.gov!sdd.hp.com!hp-cv!hp-pcd!hpcvsnz![e-mail]
Subject: A question
To: [e-mail]

John Derry ([e-mail]) wrote:
: If I am given two choices as follows on some inexpensive coax at a hamfest
: fleamarket which do I buyY

: The cables are identical in every way, same markings, price, length, etc.

: At 144 MHz, when I measure the SWR with an accurate SWR meter one cable
: gives a SWR = 10 and the other gives SWR = 6.  (SWR being measured at one
: end and the other end open (Or shorted.)

: Which cable should I buy?

The higher SWR indicates lower loss:  more of the reflected wave made it
all the way back to be measured by the SWR meter.  _IF_ the SWR meter
is calibrated for use with the impedance that the line is, then you
can fairly easily calculate the line loss from the measured SWR.

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Date: Fri, 25 Feb 1994 15:36:23 GMT
From: mvb.saic.com!unogate!news.service.uci.edu!usc!howland.reston.ans.net!europa.eng.gtefsd.com!library.ucla.edu!csulb.edu!csus.edu!netcom.com!netcomsv!bongo![e-mail]
Subject: Design of Yagi Antenna
To: [e-mail]

In article <2kktk7$[e-mail]> [e-mail] (C H Teo) writes:
>
>I'd like some information about designing Yagi antennas.
>It will be appreciated if you could send me a post on the
>subject or direct me to FTP sites which holds info/FAQs
>etc.

    Besides the excellent handbooks produced by the ARRL and RSGB,
there are also many books on on antennas, some exclusively about
Yagis available.



--
Julian Macassey, N6ARE  [e-mail] Voice: [phone]
Paper Mail: Apt 225, 975 Hancock Ave, West Hollywood, California 90069-4074

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Date: 25 Feb 1994 16:58:32 GMT
From: mvb.saic.com!unogate!news.service.uci.edu!usc!elroy.jpl.nasa.gov!news.aero.org!Aero.org![e-mail]
Subject: Simple Signal Question
To: [e-mail]

In article <2kk57u$[e-mail]>, [e-mail] (Dane L. Cantwell) writes:
|>
|> A friend and I were talking about cellular phones.  He is in the market
|> for one and we were talking about the merits of a "full size" phone at 3
|> watts versus a portable at 0.6 watts.  It was my point that the extra
|> transmission power is discounted because the signal received at tower is
|> related to the square of the distance to the tower.... therefore you
|> don't get anything like 5 times the range with a 3 watt model over a 0.6
|> watt unit.  Is this right in theory?  How about the real world?
|>
|> I realize that the assumption I am making assumes a point source that
|> would radiate in all directions.  How close is this assumption to the
|> real world antennas?  Comments please.
|>
|> Dane Cantwell - [e-mail]
|> Petroleum Engineer
|>
|>
Seeing as how you have such a great name, I couldn't help but throw in my two
cents :-)

Another thing to think about is that, with most systems today, the cell receiving
antenna sends commands to change the output power of the phone.  That is, the
base antenna will issue commands to step down (or up) the output power of the
phone so that the minimum power necessary for the connection is used.

Great, you say, I will just wire up my phone so that it ALWAYS blasts out the
3 watts regardless of what anybody says.  Unfortunately, most systems recognize
this and, if you don't do as they say, the system will just cut you off.

Having the higher power unit might be worthwhile if he is going to spend a lot
of time in fringe coverage areas, but if the area he will use is well 'celled'
he should probably put his money in a better antenna.

So much for my comments.

Yours,
cantrell

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End of Ham-Ant Digest V94 #48
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