SCANTENNA Directivity ??

[VA3CAF]

I have a Scantenna on order but, am wondering if anyone has 'confirmed' information as to whether this beast is omni or is it directional. In looking at it, she would appear to be somewhat directional but have not found any info in its discriptors to confirm or deny it. I know there are going to be responses suggesting that theirs are working fine just mounted somewhere, but I am not living in close proximity to most of the action, so if I have to squirt in a particular direction, I would like to know up front so I can mount it on one of my rotor systems. Again. thanks up front for any input.

 

[Highlander_821]

It sort of depends on how it is mounted. If you mount it to a metal antenna mast, it will have a *little* directivity. The metal mast will act as a reflector, making the antenna slightly favor the direction going away from the mast and towards the antenna. A Fiberglass, composite, or other non-metallic mast or support pole would not have this effect. Mounting it on the side of a tower would give you even more directivity, but still nothing drastic.

It will still be pretty much omnidirectional. If there is a tower or station in particular which may be on the fringe of your ability to receive the signal, then maybe mounting the antenna to "face" that direction might give you a little help on a marginal signal from that direction.

I think you will be happy with the antenna, I have had mine for several years, no trouble with it at all, it does eveything I wanted it to do, money well spent. My Radioshack discone that I bought about the same time as the Scantenna started shedding elements right from the start, money NOT well spent. You look at that thing funny, it will drop an element.

 

[VA3CAF]

Scantenna shoot

Thanks for the input and your suggestions make sense. And yep, we're familiar with the dropping of elements from infamous RS AE. I finally ended up arc\spot welding the elements into place and to date, they've got the message and are staying put. Also added a 5/8 w/l 800 mhz mobile whip into the top of it, and that works fairly well too. We'll see if anyone else out there has some input. 73

 

[kb2vxa]

Hi Lander and all,

Thanks for the good account of pattern distortion except for one small item.
"Mounting it on the side of a tower would give you even more directivity, but still nothing drastic."
Side mounting on a tower gives a cardioid pattern, that is the letter D more or less. Amateur repeaters sometimes take advantage of this effect in order to protect other co-channel repeaters. By placing the other repeater in the shadow there is far less interference between them.

On to the magical land of Ontario, there have been reports of the Scantenna being slightly directional. If you have weak reception of a particular transmitter slightly rotating it usually clears it up a bit. The only way to eliminate the pattern distortion caused by the mast and coax is to use a non-conductive mast and run the coax off at 90 degrees from the antenna. Since this is not practical a slight null in the pattern is tolerable.

 

[sony]

Channel Master

Don't forget the Channel Master antenna is also a good one similiar in design.

 

[TeRayCodA]

Don't forget the Channel Master antenna is also a good one similiar in design.

If you can still find one -long discontinued.

 

[sony]

If you can still find one -long discontinued.

I have and am using two of them.

 

[VA3CAF]

Scantenna Directivity

Tnx Warren for your input. I marvel as to how a thread wanders off in various directions. As I had initally indicated we were dealing specifically with the Scantenna, and trying to source 'good' information on that item only.
Given what info you and others have prevailed on this subject I anticipate swapping a couple of 7 el 440 yagi's off of one rotor system that has a non-conductive mast in it and giving the incoming Scantenna a home there. I can now fix mount the yagi's directly South into Rochester off the main tower, so this is good.
If this thread is still avail after the install I will input what I find in as much as any directivity found on the long haul signals for the info of others. Agn tnx es 73

 

[kb2vxa]

Hi again,

You're welcome, you confirmed the discussion needed just a bit of clarification. A 70cM Yagi won't have quite the gain and directivity on 460 as it does on 432 but it should give satisfactory results for receiving. Good luck and the thread isn't going anywhere, it'll be right here waiting for you to reopen when you have the results to tell us about.

Oh, being the Scantenna is a dipole we HAMS know about metallic objects in the near field, don't we? (;->) Just to add a bit of broadcast engineering experience to the mix for the fun of it, AM broadcast stations sometimes experience pattern distortion from nearby towers unrelated to the transmitter. I once saw up close and personal how a water tower is detuned by making it into an antenna. By running wires up the side, connecting them at the top and adding an ATU at the bottom it became in effect a grounded vertical folded unipole making it invisible to RF at the transmitter frequency thus eliminating it's effect on the pattern.

BTW, a long time ago on a forum far away someone wrote "Never argue with a HAM!", right? (;->) Never mind guys, I don't want to hear it. Close mouth, open ears, you'll learn something.