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Re: Mode L uplink antennas



Hi Cliff:

The Directive Systems antenna specs indicate that the loop Yagis are 
optimized for 1269 MHz. and 1296 MHz.  Where did you find information that 
the antennas were designed for 1283 MHz.?  The antenna documents on-line at 
the Directive Systems web site show the element dimensions and spacing for 
the 1296 MHz. and the 1269 MHz. loop Yagis are different from each other. 
Did I miss something?

The documents for all of the various loop Yagis are available at:
http://www.directivesystems.com

The following is a quote from the Directive Systems website:

"Directive Systems manufactures all of the original antenna designs of Down 
East Microwave. These loop Yagi antennas have set the standard for microwave 
experimenters and find wide use in commercial applications as well".

Directive Systems is operated by Dave Olean, K1WHS.  Down East Microwave and 
Directive Systems products have been highly regarded by serious VHF/UHF and 
Microwave operators for many years.

I have a quad array of the Down East Microwave 45 element loop Yagis for 
1296 MHz. and one of the 1269 MHz. 45 el. loop Yagis.  The 1269 MHz. loop 
Yagi has a VSWR of 1.1:1 at 1269 MHz.  Each of the 1296 loop Yagis have a 
VSWR of less than 1.1:1 at 1296 MHz.  The VSWR on each of the antennas was 
easily adjusted by slight adjustments in the shape of the driven element. 
This is explained in the documentation.

I have no connection to either Down East Microwave or Directive Systems, 
other than being a VERY satisfied customer for many years.

73,

Woody
KJ4SO
AMSAT # 5562

----- Original Message ----- 
From: "Cliff Buttschardt" <cbuttsch@kcbx.net>
To: "Woody" <kj4so@nc.rr.com>
Cc: "amsat bb" <amsat-bb@amsat.org>
Sent: Saturday, March 26, 2005 1:16 PM
Subject: Re: [amsat-bb] Mode L uplink antennas


> Hi Woody, yes that is the very antenna that I was searching for to advise
> Keith!  Good you found the URL as all I had was hard copy.  This is not at
> all hard to construct.  I'd like to see some optimization figures as it
> appears that a design for 1283 MHz might suffer a bit even when the VSWR 
> is
> minimized at 1269 MHz.  Cliff K7RR
>
> Woody wrote:
>>
>> Hi Keith:
>>
>> A search on Google turned up construction details on a 24 element loop 
>> Yagi
>> by Directive Systems, which until earlier this year, were sold by Down 
>> East
>> Microwave.  Now, they sell their products direct.  Directive Systems,
>> manufactures high quality VHF/UHF and microwave antennas and accessories.
>>
>> Loop Yagis are great antennas on 1296 and 1269 MHz.  This antenna is
>> advertised as 18 dBi gain with 24 elements on a 6' boom.  It could easily 
>> be
>> shortened as needed for a satellite antenna.
>>
>> Check out:
>> http://www.directivesystems.com/PDF/2424LYRMK.PDF
>>
>> 73,
>>
>> Woody
>> KJ4SO
>> AMSAT # 5562
>>
>> ----- Original Message -----
>> From: "Keith Bainbridge" <vk6xh@arach.net.au>
>> To: "amsat bb" <amsat-bb@AMSAT.ORG>
>> Sent: Friday, March 25, 2005 8:07 AM
>> Subject: [amsat-bb] Mode L uplink antennas
>>
>> >I am having great difficulty finding details to make a 1269 mhz yagi 
>> >etc.
>> > All the info I can find on the net relates to 1296 mhz, I scaled one of
>> > Kent's 10 ele " Cheap " yagis to 1269 but the swr / bandwidth is 
>> > extremely
>> > small ( ie 60 khz ) so I guess I'm doing something wrong here.
>> > Has anyone any designs available for this freq, or can you point me in 
>> > the
>> > right direction maybe ??
>> > I dont mind if its a yagi, a quagi or what ever, but I dont want to 
>> > build
>> > yet another helical. My success rate with helicals is 7 made, 2 
>> > actually
>> > worked, and thats from 2mtrs to 10 ghz!!
>> > And it was the 5ghz one that was the best !
>> > I would buy a Tonna  but they are so expensive to ship to Australia.
>> > Any leads would be appreciated, there is a gap on the rotator just 
>> > waiting
>> > for another antenna !!
>> > 73 de Keith
>> >
>> > --
>> > Keith Bainbridge
>> > VK6XH
>> > N.C.R.G
>> > Amsat NA #35338
>> > W.I.A.
>> >
>> > Make the change
>> > Support Mozilla Thunderbird  & Firefox
>> > ----
>> > Sent via amsat-bb@amsat.org. Opinions expressed are those of the 
>> > author.
>> > Not an AMSAT member? Join now to support the amateur satellite program!
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>> ----
>> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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>
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