GMRS Repeater Antenna

[WRVY769]

Would I notice a difference from a 6db gain antenna to a 12db gain antenna I live near some minor hills and quite a bit of trees.

[SteveShannon]

27 minutes ago, WRVY769 said:

Would I notice a difference from a 6db gain antenna to a 12db gain antenna I live near some minor hills and quite a bit of trees.

Absolutely, but whether the difference is positive or negative depends entirely on all the other variables  

 

[WRVY769]

what is some of the other variables. sorry I don't know very much about dB gain and antenna. 

[SteveShannon]

3 minutes ago, WRVY769 said:

what is some of the other variables. sorry I don't know very much about dB gain and antenna. 

So a 12 dB gain is simply more focused in some directions. As an example it might not hear signals that are above, below, or to the sides or rear of it, while a 6 dB antenna is usually more receptive throughout a wider swath. Study the propagation patterns of the antennas you’re looking at. 
Many commercial antennas have less gain in order to be less directional. 

[WRVY769]

this is the antenna. it's a vertical is there a way to direct the patterns in one direction. 

Comet Antennas GP-9NCA Comet GP-9NCA GMRS/FRS-Commercial Dual Band VHF/UHF Base Vertical Antennas | DX Engineering

[SteveShannon]

9 minutes ago, WRVY769 said:

this is the antenna. it's a vertical is there a way to direct the patterns in one direction. 

Comet Antennas GP-9NCA Comet GP-9NCA GMRS/FRS-Commercial Dual Band VHF/UHF Base Vertical Antennas | DX Engineering

No, that’s a different type of antenna. The most common antenna used to direct RF in a given direction is called a Yagi-Uda antenna. 
That’s a good antenna though. But as some reviewers point out it has a fairly flat pattern. 
https://www.eham.net/reviews/view-product?id=2455

[WRVY769]

Would I receive a directed signal or more of a open signal with this antenna.

[WRVY769]

what does it mean by is has fairly flat pattern? 

[SteveShannon]

Just now, WRVY769 said:

Would I receive a directed signal or more of an open signal with this antenna.

Let me see if I can find a video that explains. This is more than I can explain one question at a time and still get to bed tonight.
I’ll be back. 
 

[SteveShannon]

5 minutes ago, WRVY769 said:

what does it mean by is has fairly flat pattern? 

Like a pancake. The signals go mostly horizontal instead of spreading up and down. 

[SteveShannon]

3 minutes ago, Sshannon said:

Let me see if I can find a video that explains. This is more than I can explain one question at a time and still get to bed tonight.
I’ll be back. 
 

 

[WRVY769]

I will take a look at this and thank you for all your help. 73

[SteveShannon]

Antennas are the most interesting subject in radio. Enjoy the video. There are lots of good videos out there. 

[KAF6045]

 

16 hours ago, WRVY769 said:

what does it mean by is has fairly flat pattern? 

Ignore the frequency and free-space titles (though the first IS a halfwave in free space)

This is the pattern of a half-wave dipole in free space. It has 2.16 dB gain over an isotropic emitter.

These are over (as I recall -- old images) "perfect ground" at two different heights. Note the reduced gain.

A high gain vertical antenna will squeeze those patterns into much narrower "beams". Depending upon how high  it is mounted, and surrounding terrain, your narrow high-gain beam may just be hitting lots of trees and hills, while a lower gain might go a bit above said terrain.

This is an antenna over "real ground" -- note the near 7dBi gain, but also note the elevation angle it occurs at.

 

[fremont]

6 dB is one S unit..... just sayin'