78MHz Antenna question...

[robb]

Hi all,

Just a simple question. The ambos and firies in tasmania use VHF, around 76-79Mhz and I know that when you have an antenna cut to specific freq it has 4mhz either side, I was thinking of having one of the antennas (pictured) cut to 78Mhz however this is the big question:

Is it better to get the 1/4 wave one at 96cm OR the the 1.5m one? I plan to use the antenna inside for the time being.

Thanks

[hotmetal1000]

The longer one would generally have more gain.

[bodyguard]

I personally would look for a dual band 144/470mhz ham radio antenna, it would harmonically drop to those freqs.
I used one in NZ for monitoring local fire on 76Mhz while monitoring police on 468mhz and pagers on 158mhz through a splitter

[Comint]

The longer one would generally have more gain.

I initially thought that too, but if you can read the fine print, they both say Unity gain.

The short one is basically 1/4 wave at 78 Mhz in its present state, give or take a couple of millimetres.
As for the long one, given the 'gain' comments, it is hard to say what it is, when you consider the helical windings, but seeing it only covers 70 to 83 MHz, and you're only using it for receiving, I wouldn't bother cutting it at all.

As for which one to choose. Remember the saying: The more metal in the air, the better the signal.

--
Comint

[robb]

Thanks, from the sounds of it - the longer the better and just curious why I would not want this cut to 78mhz? :sc

[hotmetal1000]

I did see that unity gain, as for what that is supposed to mean I don't know.

[Comint]

Thanks, from the sounds of it - the longer the better and just curious why I would not want this cut to 78mhz?

You generally only cut these type of antennas to frequency, if they are to be used for transmitting.

I did see that unity gain, as for what that is supposed to mean I don't know.

Unity Gain means 0db gain (or loss). In other words no Gain or Loss.

[hotmetal1000]

Thanks, from the sounds of it - the longer the better and just curious why I would not want this cut to 78mhz?

You generally only cut these type of antennas to frequency, if they are to be used for transmitting.

I did see that unity gain, as for what that is supposed to mean I don't know.

Unity Gain means 0db gain (or loss). In other words no Gain or Loss.

Just done some research on unity gain for my own understanding, basically a unity gain antenna will transmit in all directions evenly including up and down.

antenna.gif

[robb]

Thanks for the help guys!

[melbourneradio]

this is a bit old ,,, but i use the RFI - Stainless mobile antennas , here in vic for RAV or AV as they are now known and no problems i will get the details for you