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?.
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.
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.
Re: Scanner Aerials?#139503 11/17/0305:51 AM11/17/0305:51 AM
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! ).
You could add an ATU to help tune to the band you're scanning at any one time.
Re: Scanner Aerials?#139504 11/17/0311:00 AM11/17/0311:00 AM
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.
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!.
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!. 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.