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#139498 11/16/03 12:24 AM
Joined: Jul 2002
Posts: 8,443
Likes: 3
Trumpy Offline OP
Member
Sorry but this doesn't directly relate to Electrical work.
But I'm after a Base station aerial for my wideband scanner (100kHz-1300MHz) and I was wondering if there was such a thing as an Active Aerial with this sort of bandwidth?.
Or at least an Aerial that I can put an RF amplifier on to?.
Anyone have any ideas?. [Linked Image]

#139499 11/16/03 12:49 AM
Joined: Apr 2002
Posts: 2,527
B
Moderator
A passive device—but discone antennas are supposed to have very wide bandwidth. www.google.com/search?q=discone+antenna

#139500 11/16/03 03:23 PM
Joined: May 2001
Posts: 717
G
Member
Trumpy,
This company has a lot of good stuff, active and passive.
http://www.ccrane.com/

#139501 11/16/03 04:25 PM
Joined: Aug 2001
Posts: 7,520
P
Member
Discone antennas are generally reckoned to be a reasonable compromise, and don't seem to work too badly if you get them reasonably high.

You can get wideband preamps to connect in-line, but covering this sort of range with one amplifier is very problematical, and such amps frequently give bad cross-modulation if you have any very strong signals nearby.

#139502 11/16/03 07:03 PM
Joined: Nov 2002
Posts: 794
Likes: 3
W
Member
As crude as it sounds, a long piece of wire would be lowest cost and work the best for a range of 100KHz to 1.3GHz. Or do you mean 100MHz to 1.3 GHz? A discone is said to work well for that. Best to avoid preamps. Use heavy gauge coax cabe for lower loss especially at the GHz end.

#139503 11/17/03 06:51 AM
Joined: Aug 2001
Posts: 7,520
P
Member
Sorry, I missed the 100 kilohertz. [Linked Image]

Discones won't give fantastic performance below VHF. A long wire (e.g. an inverted-L) would certinly be a good cheap antenna for the MF and HF ranges. Bearing in mind your comments about neighbors in the general area, it's also worth considering that a long wire is fairly unobtrusive (tell 'em it's a big washing line! [Linked Image]).

You could add an ATU to help tune to the band you're scanning at any one time.

#139504 11/17/03 12:00 PM
Joined: Aug 2002
Posts: 1,081
T
Member
I have a discone here, not extremely high but high enough to pull in just about what I need.

The big problem I have is with either intermod or cable TV interference. The worst problem seems to be FM radio stations (108 MHz and lower) on the aero frequencies.

I used to have the antenna in my attic, which gave me weak signal reception but no interference. Once I put it outside on a mast, the intermod did its thing. I found that if I use my scanner's 10dB attenuator, the interference goes away and the local airport tower is still loud enough to receive.

#139505 11/18/03 12:24 AM
Joined: Jul 2002
Posts: 8,443
Likes: 3
Trumpy Offline OP
Member
Thanks for your ideas guys!.
Between myself and my neighbour (who is also a Ham), we are starting to amass a small antenna farm on both of our roofs.
Mind you, I have never had a TVI complaint from him and vice-versa.
The Discone sounds like the way to go and it won't look out of place with the other 4 aerials on the roof, (not including the TV aerials) anyway!. [Linked Image]

#139506 11/29/03 07:50 PM
Joined: Jul 2002
Posts: 8,443
Likes: 3
Trumpy Offline OP
Member
Have just finished the installation of a Diamond D-130J Discone on my roof.
And Good Lord, it's amazing what this little scanner will "pull in" with an Outside aerial on it!. [Linked Image]
I'm getting really good reception on 2m and 70cm, where before there was just faint carriers being recieved.
Should have done this ages ago. [Linked Image]

#139507 11/29/03 08:03 PM
Joined: Aug 2002
Posts: 1,081
T
Member
Mike:

I have the exact same Discone. Does wonders!

Enjoy.


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