Subject: Kurt, help us please!
From: w8jitom@aol.com (W8JI Tom)
I've just read the most interesting antenna article I've ever read. August
CQ, Antennas and Digital communications. I think everyone will enjoy this
article, especially Kurt N. Sterba. I can't wait 'til he sees it!
Among the highlights are the following bits of wisdom:
1.) An antenna must be a resonant length to radiate efficiently.
2.) Due to the mirror image...the greater the antenna's height, the
greater its gain.
3.) An antenna has the same pattern on receive and transmit ONLY if the
elements and feedline have the same impedance.
4.) Making the antenna thicker lowers both Q and gain. Making the antenna
thinner raises Q and gain.
5.) Q is determined solely by the ratio L and C in the antenna.
6.) The reason 468/f is used instead of 492/f is because of a K factor
related to the ground. If the wire was in space 492/f would work just
fine.
7.) A quad provides improved rejection of terrestrial noise over a Yagi.
8.) With any beam antenna of any beamwidth you get another 3 dB by
stacking another beam exactly 1/2 wl away.
9.) Coax feedlines MUST be cut to a multiple of 1/2 wl or the antenna will
not work because of backpressure.
10.) Coax feedlines must be the correct size because, like a pipe and a
water pump, if too large or to small they won't match the pump. The
electricity will slow down and maybe even stop and bounce backwards in
waves. Both the diameter and length of the pipes feeding our antennas are
important. They have to match the flow, so they can't be too big or too
small....too long or too short.
I wonder if anyone else enjoyed this article as much as I did?
73 Tom
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From: w8jitom@aol.com (W8JI Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Kurt, help us please!
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>From wb4iuy@nando.net (Dave Hockaday) Thu Jul 25 15:19:29 1996
From: wb4iuy@nando.net (Dave Hockaday) (Dave Hockaday)
Subject: Antenna article
Message-ID: <199607251419.KAA21923@bessel.nando.net>
>I've just read the most interesting antenna article I've ever read. August
>CQ, Antennas and Digital communications. I think everyone will enjoy this
>article, especially Kurt N. Sterba. I can't wait 'til he sees it!
Hahahahhehehehehe....thanks for the laugh, Tom. I really needed it today.
I liked this one...
>3.) An antenna has the same pattern on receive and transmit ONLY if the
>elements and feedline have the same impedance.
I really loved this one, hehhe...
>9.) Coax feedlines MUST be cut to a multiple of 1/2 wl or the antenna will
>not work because of backpressure.
Gawd...what planet is this dude from??
>10.) Coax feedlines must be the correct size because, like a pipe and a
>water pump, if too large or to small they won't match the pump. The
>electricity will slow down and maybe even stop and bounce backwards in
>waves. Both the diameter and length of the pipes feeding our antennas are
>important. They have to match the flow, so they can't be too big or too
>small....too long or too short.
hehehhee...
Dave Hockaday Wb4iuy
wb4iuy@nando.net
http://www.webbuild.com/~wb4iuy/teara.html
(alternate)http://www.geocities.com/TheTropics/3341/
http://www.RTPnet.org/~fcarc/
(alternate)http://www.geocities.com/TheTropics/3212/
http://www.webbuild.com/~wb4iuy/
(alternate)http://www.geocities.com/TheTropics/3489/
http://www.geocities.com/TheTropics/3349/
http://www.RTPnet.org/~rdrc/
>From jholly@hposl62.cup.hp.com (Jim Hollenback) Thu Jul 25 15:34:00 1996
From: jholly@hposl62.cup.hp.com (Jim Hollenback) (Jim Hollenback)
Subject: How Much does a DB Cost?
References: <Pine.SOL.3.93.960725003057.21409B-100000@Pegasus>
Message-ID: <9607250734.ZM11523@hpwsmjh1.cup.hp.com>
On Jul 25, 12:35am, Charles H. Harpole wrote:
> Subject: Re: How Much does a DB Cost?
> DBs costs relate to the weather. EVERYBODY knows that antennas worked
> on in a snowstorm (etc., you name the weather, like 30 below) produce more
> gain than those assembled in nice weather. I am now assembling a HyTower
> in 110 degree plus effective temp. here in sunny Fla. and place all
> readers on alert to the killer signal it will output. de K4VUD
I don't think so Charles ... The weather factor only applies when you
must wear a lot of clothes and work with gloves. There is addition gain
for work done in high wind and snow conditions. Work done in warm, sunny
conditions on the other hand add a negative DB factor ... I just don't
understand how anyone from Fla. can be heard on the bands.
73, Jim 'from northern nine land', WA6SDM
jholly@cup.hp.com
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