Outside/Inside antenna with gain

bravo14

Member
Premium Subscriber
Joined
Feb 18, 2005
Messages
3,813
Location
#850Strong
Good Evening, I am using this SpectrumForce Wideband Antenna with Mag Mount and BNC | Scanner Master for about 7 years I have 2 of them 1 for inside in my room other is for car when traveling or going somewhere for a few days. When bands do open up I can get 50 miles to several hundreds of miles on v/uhf to 900mhz. I was looking a magnet where I can use 118-1ghz range. I know if you get a tri band gain is not all there. I am trying to not use more than 2 antennas. Any ideas what to look for?
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
13,859
Location
SNCZCA01DS0
I was looking a magnet where I can use 118-1ghz range. I know if you get a tri band gain is not all there. I am trying to not use more than 2 antennas. Any ideas what to look for?
There really isn't anything to listen to above the 900MHz LMR band, at least not anything your scanner will decode. 900MHz band is going to change, and while there will still be some stuff to listen to, a chunk of the spectrum is going to become an LTE type network.
I'd focus on the stuff below 900.

I haven't seen any good tri band antennas that have gain. Most them out there are either designed for multiband public safety radios where gain isn't as important, or for scanner listeners, where size/cost is usually the concern.

There may be some ham type antennas that may cover the 900MHz band, as well as VHF/UHF, but I've never really looked.

The Larsen NMO-150/450/800 is a good antenna, but doesn't have gain on VHF. It does have gain on UHF and higher (but not a lot). Using one of those, putting it in an ideal location and keeping the coax run short, or using higher grade coax is probably a good tactic.
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
13,859
Location
SNCZCA01DS0
Where I live there is 380 & 400 Vhf & Uhf 700 & 800 analog to digital p25 to DMR. I'm about 20+ miles from the airport once awhile I'll hear the aircraft. I was looking at theantennafarm site found this one https://www.theantennafarm.com/catalog/larsen-nmo150-450-758-8932 not sure if it will pick up 380 stuff or aircraft.
Yeah, that's the updated/newer version of the one I linked to.

It'll pick up 380MHz, but not as well as a band specific antenna. Those antennas are marketed for scanners as well as the new multiband public safety radios. Since 380 is military use, there's not as much a market for that.

Your other options for mobile or base use is to get individual antennas dedicated to those bands and combine them with a triplexer. That's going to be expensive and require some roof real estate.

Aircraft coverage should work just fine if they are in the air. On the ground, you won't get much range, the systems are not really designed for that. Usually at airports they only need a mile or two range on the ground. Once the aircraft are up in the air, coverage isn't an issue. Trying to get ground level airport coverage from 20+ miles away is going to be a challenge.
 

vagrant

ker-muhj-uhn
Joined
Nov 19, 2005
Messages
1,652
Location
California
Here is a VSWR and S11 plot for a SpectrumForce antenna. It was sitting on a metal filing cabinet in my office about 20" x 16" in size. I previously used this as well on my vehicle and it worked well enough, but most signals are booming in to my location so it doesn't take much. For $20 it is definitely better than various other antennas I have paid more for and later put in the junk bag.

It was blurry cam day at the office. That first dip is in the 2m amateur band.
IMG_1616.jpgIMG_1617.jpg
 

bravo14

Member
Premium Subscriber
Joined
Feb 18, 2005
Messages
3,813
Location
#850Strong
I called HRO like 30 mints ago and told them what I was planning on doing and asking about gain. He told me just buy a discone antenna should cover all bands. I said it is mostly indoors and I was saying maybe buy 2 separate antennas 1 for vhf/uhf the other for 700/800/900mhz side. He said just do Discone......
 

iMONITOR

Member
Premium Subscriber
Joined
Sep 20, 2006
Messages
8,457
Location
MACOMB, MI.
I called HRO like 30 mints ago and told them what I was planning on doing and asking about gain. He told me just buy a discone antenna should cover all bands. I said it is mostly indoors and I was saying maybe buy 2 separate antennas 1 for vhf/uhf the other for 700/800/900mhz side. He said just do Discone......
Discone antennas are not optimal for the 700/800/900 MHz bands. They also have zero gain.
 

bravo14

Member
Premium Subscriber
Joined
Feb 18, 2005
Messages
3,813
Location
#850Strong
Discone antennas are not optimal for the 700/800/900 MHz bands. They also have zero gain.
I told him that. Last time I had one it didn't do well on 800 that was back in 2000. It did good on vhf/uhf side.
 

iMONITOR

Member
Premium Subscriber
Joined
Sep 20, 2006
Messages
8,457
Location
MACOMB, MI.
For a one-does-all solution I would suggest:

OmniX Scanner Base Antenna
 

paulears

Member
Joined
Oct 14, 2015
Messages
387
Location
Lowestoft - UK
Let's be honest here. The VSWR plots show you where the antenna is resonant. At these points you get pretty much unity gain - so at some points you might be getting because of the extended capture area a little more than 0dB gain, but for most of the bands you're getting far, far less gain. A discone has no gain, but the performance holds up over a much, much wider range - that's what they're for.

Very few antennas of this kind have any real gain at all, and the frequencies where they hardly perform are numerous.

Dual and triple danders have gain bit usually at amateur frequencies, that's where it's vital to how low VSWR, so that's where the performance is directed. Airband benefits from the high angles of approach for the line of sight transmissions. Performance at some frequencies is truly dire. Hopefully this is where you have no listening interest.
 
Top