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  • Member
  • Member For: 19y 3m 19d
  • Gender: Male
  • Location: Melbourne
Posted

Are they the same decibel rating?

When it comes to the UHF aerials, the decibel rating determines their range and effectiveness.

Check this out to explain the differences...

Firstly let's look at Gain - If you look at the diagram below, with the vertical line representing the antenna, the outer circles indicates how the signal is transmitted with various gain antennae. In summary the higher the gain the more direct and pinpoint the signal, thus longer distance but far less 'rollover' effect, consequently reducing performance in hilly areas.

Ant-Prop-Gain.jpg

The diagram below typically shows what happens to the signal between two vehicles - note how the signal with a 3db gain antenna actually reaches the second vehicle s antenna but the 6db does not

ANT-PROP-HILLS.jpg

Ideally if would be advantageous to change antennas when in flat country and also when in hilly country - This situation is certainly not ideal, so a compromise is the only answer - In summary the best all-round choice is 4.5-6db

Hope that helps mate.

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  • Member
  • Member For: 20y 6m 2d
Posted

Thanks twisty....makes alot of sense looking at the diagrams

both of my antennas are 4.5 - 6 db

just did a little drawing of both antennas on the car

so effectivly both of these antennas would work exactly the same if they where on the car like in the pic right? if they were a different db rating then it would b a different story

post-8377-1220357379_thumb.jpg

  • Member
  • Member For: 19y 3m 19d
  • Gender: Male
  • Location: Melbourne
Posted

Haha, great artwork!

Yeah, they'll have the same effectiveness, if they've got the same DB Gain, and they're mounted the way you've skillfully drawn. haha.

  • Member
  • Member For: 20y 6m 2d
Posted

haha thanks for the compliments

but seriously that's for the advice and diagrams, made things alot clearer!

  • Here since the start...
  • Legacy Donating Member
  • Member For: 23y 4m 24d
  • Gender: Male
  • Location: Victoria
Posted

Threads merged. :spoton:

  • Legacy Donating Member
  • Member For: 20y 5m 26d
  • Gender: Male
  • Location: nsw
Posted

imo the best mobile antenna is a rfi evelated feed 4.5/6.5 db.

they call it a 6.5 but I cant see a 4.5 gaining with just an elevated feed.

  • 1 year later...
  • I see a red door and I want to paint it black
  • Legacy Donating Member
  • Member For: 16y 10m 25d
  • Gender: Male
  • Location: Far north queensland
Posted

ok old thread but I'm getting a uniden uhf/scanner and was wondering if anyone could recommend a small/discreet antenna for me

  • 2 weeks later...
  • Member
  • Member For: 18y 3m 25d
  • Gender: Male
  • Location: Broken Hill, NSW
Posted (edited)

Hey Sideways,

I recently got a "Clear Glass Antenna" which is made by Laser Antenna and it works great!

Granted it doesn't have the range of a proper external antenna, but it does the job.

Edited by adaze
  • I see a red door and I want to paint it black
  • Legacy Donating Member
  • Member For: 16y 10m 25d
  • Gender: Male
  • Location: Far north queensland
Posted

thanks man looks sweet, but I got and awesome deal of fleabay on a uhf/6db antenna combo

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