Vertical Plane Chart

When looking at this chart for an omni antena,

http://www.hyperlinktech.com/web/hg2415u_pro.php

can someone translate this in terms of what is happening in center of
chart?

I understand "Vertical Beam Width 8° " concept, but what I'm wondering
if the vertical beam width is wider at its source?

thanks,

(E-Mail Removed) wrote:
>
> When looking at this chart for an omni antena,
>
> http://www.hyperlinktech.com/web/hg2415u_pro.php
>
> can someone translate this in terms of what is happening in center of
> chart?
>
> I understand "Vertical Beam Width 8? " concept, but what I'm wondering
> if the vertical beam width is wider at its source?

Outside the near field (say 20 times the largest dimension of the antenna)
the beam will spread out completely linearly.

(E-Mail Removed) wrote:

> When looking at this chart for an omni antena,
>
> http://www.hyperlinktech.com/web/hg2415u_pro.php
>
> can someone translate this in terms of what is happening in center of
> chart?
>
> I understand "Vertical Beam Width 8° " concept, but what I'm wondering
> if the vertical beam width is wider at its source?
>
> thanks,

Part of what you are seeing on the center of the chart are "lobes" that
antennas have. Nothing out of the ordinary there.

Not having experimented with them all, I won't claim any degree of
expertise. But there are many stories from people using "high gain" omni
antennas who have had a shitload of problems because of overshooting
their clients or not having the omni mounted correctly. An 8dbi omni is
more forgiving if you aren't exactly sure of what you are doing.

On Sat, 01 May 2004 17:56:36 GMT, Ian Stirling
<(E-Mail Removed)> wrote:

>> When looking at this chart for an omni antena,
>>
>> http://www.hyperlinktech.com/web/hg2415u_pro.php

>> I understand "Vertical Beam Width 8 " concept, but what I'm wondering
>> if the vertical beam width is wider at its source?

>Outside the near field (say 20 times the largest dimension of the antenna)
>the beam will spread out completely linearly.

Thanks....specifically, if say a person lived 1000' away from this
antenna, but say 20' below the 8 degree beamwidth, would this work.
I'm not understanding the graph at its center. Is it 360 degree beam
there for short distances in the Vertical plane?

Problem is, if I setup this wireless system with a total of five
people, over four miles, you have four different directions to reach
with one antenna. Hence, omni would work for four of these people,
but not the person living next to 75' tower.

(E-Mail Removed) wrote:
> On Sat, 01 May 2004 17:56:36 GMT, Ian Stirling
> <(E-Mail Removed)> wrote:
>
>>> When looking at this chart for an omni antena,
>>>
>>> http://www.hyperlinktech.com/web/hg2415u_pro.php
>
>>> I understand "Vertical Beam Width 8 " concept, but what I'm wondering
>>> if the vertical beam width is wider at its source?
>
>>Outside the near field (say 20 times the largest dimension of the antenna)
>>the beam will spread out completely linearly.
>
> Thanks....specifically, if say a person lived 1000' away from this
> antenna, but say 20' below the 8 degree beamwidth, would this work.
> I'm not understanding the graph at its center. Is it 360 degree beam
> there for short distances in the Vertical plane?

Microwaves work like light.
Consider it like a lampshade.
To show the intensity that it shines with over all angles, you can use
two graphs, one which shows the intensity variation as you go round
it, and the other as you go above and below it.

In this case, it peaks at 0 and 180 degrees, horizontally, so it's like a
horizontal band of light, with some leakage to the sides.

The graph shows the intensity at a given angle by the distance the line
is from the origin.
Try doing this with a flashlight shined at a wall, to get an idea.