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Arrow Corner Reflector antenna

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Old 03-10-2007, 07:10 PM
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Default Arrow Corner Reflector antenna


Can anyone tell me about the 2 meter Corner Reflector antenna from Arrow? And how do they compare wth a regular 2 meter yagi antenna? What are the pro and cons of a corner reflector antenna?

Thanks,
Andy


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Old 03-10-2007, 09:17 PM
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http://tpub.com/neets/book10/42o.htm

Quote:
CORNER REFLECTOR

When a unidirectional radiation pattern is desired, it can be obtained by the use of a corner reflector with a half-wave dipole. A CORNER-REFLECTOR ANTENNA is a half-wave radiator with a reflector. The reflector consists of two flat metal surfaces meeting at an angle immediately behind the radiator. In other words, the radiator is set in the plane of a line bisecting the corner angle formed by the reflector sheets. The construction of a corner reflector is shown in figure 4-42. Corner-reflector antennas are mounted with the radiator and the reflector in the horizontal position when horizontal polarization is desired. In such cases the radiation pattern is very narrow in the vertical plane, with maximum signal being radiated in line with the bisector of the corner angle. The directivity in the horizontal plane is approximately the same as for any half-wave radiator having a single-rod type reflector behind it. If the antenna is mounted with the radiator and the corner reflector in the vertical position, as shown in view A, maximum radiation is produced in a very narrow horizontal beam. Radiation in a vertical plane will be the same as for a similar radiator with a single-rod type reflector behind it.

Check out Cebik's comments:
http://www.cebik.com/vhf/3c.html

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Old 03-11-2007, 09:23 AM
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Andy,
First, none of this is from personal experience. It's just some impressions I've gotten from reading 'Cibek' and mounting 'odd' shaped antennas.
From an electrical point of view, a corner reflector type antenna can have as much gain as a fairly large yagi type antenna. That would seem to indicate that a 'reflector' would be 'better' than an average 'smaller' yagi antenna. I would also think that 'ganging' them (multiple reflector types phased) would also yield a higher gain than multiple smaller yagis. If the yagi is of a size that would yield a gain similar to the reflector type antenna, then any advantage tot he reflector antenna is sort of mute.
Then there's the 'practical' or mechanical side of things. A yagi type antenna is fairly symmetrical and can be 'ballanced' on top of that pole you mount it on. A corner reflector type antenna isn't gonna be 'symetrical' with out some fairly complicated mounting scheme, and/or balancing weights. Can't say that would be un-doable, but it would sure be different! And then there's the 'sail' area presented to wind. I would think that a reflector type even made from 'mesh'/wire screening will have at least as much 'sail' area as a pretty good sized yag. Being 'symmetrical' also plays a big part in this cuz the action of the wind on the sail is more on one side of the mounting point of the reflector antenna than the 'other'. Balancing this 'sail' area would mean adding a 'sail' on the back end of the reflector, and that would probably turn your tower/pole into a sailboat's mast, so get ready for a nice 'ride'! lol All this assumes you'd want to be able to turn the reflector like you would a yagi for the right direction. Of course, if you don't plan to turn the reflector then some of all the above can be dismissed as irrelevant, sort of.
I've never seen many (any) rotating reflector antennas, so guess somebody thinks all this might be at least 'sort of' true. The refelctor antennas I've seen have all been for a 'fixed' direction. Considering that there isn't as much signal radiation behind them as there is for a typical yagi, that's also a factor for cutting down on interference. Not a bad idea if you only wanna hit a repeater (and someone doesn't move the @#$ repeater!).
A reflector antenna for 2 meters isn't going to be exactly 'small'. Certainly smaller than the average 10/15/20 meter yagi, but still not very small for 2 meters, you know?
So, for fixed use, and above '440, they'd be almost a really good idea. From the practical stand point, below '440, they sort of get 'un-practical'.
- 'Doc

(Not that I wouldn't like to have one, I'm just too lazy to contend with one.)

(Sorry about the length, but I do get paid by the 'word', you know. 8) )

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Old 03-11-2007, 09:33 AM
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Do you only want to recieve in one direction? is there a particular reason you are trying to block signals to the rear of the antenna (interference?) . they have more wind load than a regular yagi.
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Old 03-11-2007, 12:36 PM
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I noticed them on the Arrow's website and I just didn't know much about them. I'm looking for a good yagi and I didn't know if the corner antenna would work well for me. But it sounds like I should go with a regular yagi instead of a corner antenna.

Thanks for you help,
Andy

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Old 03-11-2007, 02:07 PM
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Corner reflectors are good for point to point links.

You can buy simple yagis for VHF for very little money. You can also use a Cubex Quad! I have a couple of Cubex's MURS prototypes and they are nice antennas!

http://www.cubex.com/

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Old 03-11-2007, 05:01 PM
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corner reflectors are indeed good
typiclly slightly less gain then simular size boom yagi
but supposedly more reliable continuous beam

i know the arrors you are speaking of
they are good
mounting bit of a problem unless mounting 2 back to back to counter balence each other

in part they have a smaller foot print requiring far less radias to turn in and so may work easier in areas with less floor plan space

i was thinking myself of trying arrows dual 144/440 corner beam with 220 mounted behind it

let us know how you go

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Old 03-11-2007, 06:31 PM
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If you would like to play around with building an antenna, 2 meters is a band that it is very easy to build antennas for.
Here is a 2 meter, 2 el quad.
Thia is a very cheap antenna, can be built from almost nothing, and will show you just how easy it is.
It is not a antenna you would want to leave up, however it will allow you to see how the idea works, and you can build it in one afternoon.

homepage.ntlworld.com/s.amesbury/M3FVB/2elementquad.htm

Simple, just some wire and a few Pcs of hardware.
You can build off of this basic idea, and learn as you go
Here is a 4 El built the same way
www.geocities.com/siliconvalley/2775/quadpic.html

Here are plans for a 4 el Quad, it is built to stand up to being mounted outside.
This is the same as the first 2 meter beam I built.
I ripped the boom from a 2x6 on the table saw, drilled the holes with a hand drill, and built this antenna on a Sunday. Start to on the air.

members.shaw.ca/ve7gds/2mtrqd.htm
Make sure that you seal the wood with some good exterior Paint, and it will suprise you how well it will hold up!

Here is a cool deal for building your own Quads, just punch in the frequency you want, and it will crunch the numbers for you!


www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=3267

Building antennas is fun, not as hard as most think, and allows you to learn how they really work, Give it a try.

73
Jeff
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