Fiberglass Omnidirectional VHF, UHF, 800, 900

[steve2004]

From: http://www.antenex.com/

I'd like to build one of those. (out of a PVC pipe) with a high gain possible.

What is inside the fiberglass tube?

I'd like to have it in 800-900Mhz range
with a 860Mhz center frequency.

is this a huge task?

Picture:
http://64.78.52.251/images/catalog/FamilyPic/fiberglass_omni_00.jpg

 

[rbm]

Normally these antennas contain an an array of 1/2 wavelength sections.

Here's an article that will give you some construction information.

Omni-Gain Vertical Collinear for VHF and UHF
http://www.repeater-builder.com/antenna/wa6svt.html

 

[steve2004]

Normally these antennas contain an an array of 1/2 wavelength sections.

Here's an article that will give you some construction information.

Omni-Gain Vertical Collinear for VHF and UHF
http://www.repeater-builder.com/antenna/wa6svt.html

Thank you.

(looks easy to build!)


here is a puzzler for me:

______________Will be covering the 800 - 900Mhz band____________

5904 divided by the desired resonant frequency of the antenna, times the velocity factor of the coaxial cable. I Will use RG-11 so it is .75

So: (5 904 / 860) * .75 = 5.14883721 The element length would have to be 5.1" Each?
18 elements = 9 dBd PVC tune will be around 25" to 30" ?

Thank you.




ps:
Can you define : "The higher the gain the narrower the elevation pattern"

 

[Al42]

5.1 * 18 = what? I guess my calculator is broken - it says 92.6". Plus the 1/4 wave element on the top and the 1/4 wave whip on top of that, bringing it to about 98.2".

"The higher the gain the narrower the elevation pattern"
The way gain is obtained is to take all the signal being transmitted up and down and squeezing it closer to the horizontal plain. While a low gain antenna may have 3db loss at 45 degrees above the horizontal, a 9db gain antenna may have 80db loss at that angle. Imagina a donut radiation pattern (for a low gain antenna). Now sit on the donut until it's almost flat. That's the radiation pattern of a high gain antenna. Notice how the outer diameter (the gain) is greater?