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Oscar 16 antenna(e) from Siretta


resonate

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Hi,

 

Looking for high gain alternative to coaxial dipoles I found this antenna : http://www.sequoia.co.uk/siretta-oscar-16-gsm-gprs-yagi-antenna_p_1553.php

http://www.siretta.co.uk/oscar-gsmgprs-yagi-antenna-p-310.html

 

I know it's quad band, but considering that antennae distribution has a filter tuned to CH69-70 it still looks interesting, considering its small size and robust design. I am using CH69 wireless.

 

What do you guys think?

manuals-Oscar 16 (Rev 1.0).pdf

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Its a yagi isn't it?  I've been using a 3 element yagi designed for hand animal transmitter tracking with very flexible memory wire elements. These Yagi's are very light, robust, compact, and inexpensive, but very effective, (easily at least 3-4x increases, the range of my Zaxcom TRXLA2's with whips)

Isn't a yagi's bandwidth narrow however - a few percent of the center frequency?

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I've been using two for diversity though not scientifically, I think spacing them apart is meant to help, I saw a formula for optimum minimum spacing in relation to wavelength somewhere but can't remember where, it may have been on JWSound? I've had one horizontal and one vertical, though the transmitter antenna is invariably vertical, I'm not sure if RF reflections from surfaces could polarize RF in any plane, I'm no RF expert, but using them does result in a significant very noticeable improvement in range, and it's just about possible to use them with a bag whilst being mobile without it all becoming too cumbersome.

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Soundtrane, yeah i know i need two. I'm just thinking about using this in a bag setup, so the second antenna would be coaxial dipole sometimes. That would somewhat work, no? 

 

I got some results from online calculator (http://www.changpuak.ch/electronics/yagi_uda_antenna.php) and it shows that a 3 element yagi tuned for 850Mhz can be as short as 141mm. That would be cool. Also, would love this to attach it to my bag : http://www.dinkumsystems.com/fleximount/    

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resonate: " What do you guys think? "

antennae (sic) are key to RF performance, and in HAM radio, probably the most tinkered with aspect of one's shack (aka station).

there is plenty written about them, and the laws of physics are the major complication, with some many variables affecting them in the real world

http://www.arrl.org/shop/ARRL-Antenna-Book-22nd-Edition/

 

 

" Do you use two at a time for diversity or one is usually enough? "

yes, but for the best diversity results, two are required.

" That would somewhat work, no? "

yes, that would somewhat work

 

pin: " I think spacing them apart is meant to help, "

for best diversity results, increased spacing improves performance

" I'm not sure if RF reflections from surfaces could polarize RF in any plane, "

absolutely.

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