Fiberglass Omnidirectional VHF, UHF, 800, 900

Status
Not open for further replies.

steve2004

Member
Joined
May 29, 2006
Messages
77
rbm said:
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"
 
Last edited:

Al42

Member
Joined
Apr 29, 2005
Messages
3,485
Location
Long Island, NY, USA
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?
 
Status
Not open for further replies.
Top