WA Radio Scanner Users' Group

G'day all

I have a question regarding the space between antenna's.

Basically I have a 27Mhz whip (2M), a 6db UHF whip, vertical scanner antenna, and my new 9db 3M UHF antenna. I want to mount all of these in the same location on my roof (customised mounting bracket).

If I have these too close together, will there be issues with interfecence?
is 15cm's gap between the antenna's enough?

Cheers

Rusty_Nail wrote:I have a question regarding the space between antenna's.

Basically I have a 27Mhz whip (2M), a 6db UHF whip, vertical scanner antenna, and my new 9db 3M UHF antenna. I want to mount all of these in the same location on my roof (customised mounting bracket).

If I have these too close together, will there be issues with interfecence?
is 15cm's gap between the antenna's enough?

For transmitting antennae, try and keep at least 1/4 wave length from any other antennae, metal objects, wire etc. So the 27Mhz antenna should be about 3 metres or more from others and the UHF CB antennae should be at least 20cm. If other stuff is too close they start to have an influence on the radiation pattern and can also greatly affect SWR.
I demonstrated this a while back with a VHF antenna mounted close to a car broadcast FM antenna. With it fully up, the SWR was way over 2 to 1. With it all the way down the SWR was perfect. The more it was extended, the worse the SWR became.

robbage wrote:

Rusty_Nail wrote:I have a question regarding the space between antenna's.

Basically I have a 27Mhz whip (2M), a 6db UHF whip, vertical scanner antenna, and my new 9db 3M UHF antenna. I want to mount all of these in the same location on my roof (customised mounting bracket).

If I have these too close together, will there be issues with interfecence?
is 15cm's gap between the antenna's enough?

For transmitting antennae, try and keep at least 1/4 wave length from any other antennae, metal objects, wire etc. So the 27Mhz antenna should be about 3 metres or more from others and the UHF CB antennae should be at least 20cm. If other stuff is too close they start to have an influence on the radiation pattern and can also greatly affect SWR.
I demonstrated this a while back with a VHF antenna mounted close to a car broadcast FM antenna. With it fully up, the SWR was way over 2 to 1. With it all the way down the SWR was perfect. The more it was extended, the worse the SWR became.

Broadcast commercial radio is crap anyway, no loss there....

nra555 wrote:Broadcast commercial radio is crap anyway, no loss there....

I don't listen to CB for the same reason.

boom tish! =D>

+1 internets to you, sir

Neither do I, you were talking about VHF?? and theres nothing wrong with the UHF band.... if you skip 476.425-477.400 Mhz

Has anyone listened to Channel 3 repeater at night? Well dont.. It's like a bloody circus...
I switched it on the other night, and it's absolute mayhem - there is actually no point to this channel.
Some old geriatric gets on there from down south and just repeats himself over and over and over, people just tell him to shut up all night.. This went on for about an hour and a half..

It's a real eye (or should I say ear) opener!!

Rusty_Nail wrote:Has anyone listened to Channel 3 repeater at night? Well dont.. It's like a bloody circus...
I switched it on the other night, and it's absolute mayhem - there is actually no point to this channel.
Some old geriatric gets on there from down south and just repeats himself over and over and over, people just tell him to shut up all night.. This went on for about an hour and a half..

It's a real eye (or should I say ear) opener!!

Sadly that's been my general experience of CB Radio for quite a while now. A lot of the time you can't turn it on if you have little kids within earshot because you don't know what kind of nonsense is going to come out of the speaker.