3 db gain vs Unity

[ScannerDude244]

I'm planning to upgrade my base antenna from my Jetstream JTB3 it works ok for a wide band scanner antenna. I'm looking to get Laird Technologies FG1520 Unity gain or Laird Technologies FG1523 with 3 db gain. Would that little 3 db gain make a big difference? I have 75ft LMR 400 btw

 

[mmckenna]

Not really.
The lower gain antennas have more bandwidth, and that can be beneficial for scanner use.

 

[ScannerDude244]

Not really.
The lower gain antennas have more bandwidth, and that can be beneficial for scanner use.

I was also looking at this one also MFB1500 or can you recommend 150-156mhz antennas?

 

[mmckenna]

Unless you have a tall tower to put it on, you really don't need much gain. Simplex range will be limited by your antenna height.
Anything you want to listen to is going to be up in the hills above you, so low gain will be fine.

I think any of those antennas you linked to would be fine for hobby use.

 

[ScannerDude244]

It's a on 30ft pole plus the height of the antenna. Not much Simplex here other than Calfire

 

[mmckenna]

It's a on 30ft pole plus the height of the antenna. Not much Simplex here other than Calfire

Yeah, gain is good for a repeater in the right location. For RX only use, not needed.

A decent unity gain base fed with good coax is a suitable setup. Anyone you'll be listening to will have their system designed for portable radio use. Having a unity gain antenna outside in the clear will work well.

 

[ScannerDude244]

Thanks again!

 

[flux4201]

Having an antenna meant to cover the spectrum you want to monitor will make a big difference. Something that actually passes with good return loss or low swr. Having good feed line can make an even bigger difference on weak signals, if that matters to you. I compared 60+' of LMR-400 to the same length of FSJ2-50 3/8" superflex hardline for an event using the same model antennas (JTB3) at the same vertical height, it made a huge difference in received signal quality. The FG's are good base antennas, installed many of them, but what they market as the frequency coverage is about what they cover in an acceptable return loss/swr, the 3db gain models are a bit worse when sweeping them compared to the unity gain model. Your putting this on a scanner, are you going to use it to receive frequencies outside of the usable range of the antenna?

 

[prcguy]

The Jetstream antenna is resonant in the amateur bands and will be degraded some in the 150-156Mhz range. The gain figures for the Jetstream are way inflated, so its hard to say how the others will compare but I think they will receive better in the 150-156 range. The Laird antennas probably adhere to dB gain over a dipole and a 3dB difference will be very slightly noticeable on weaker signals.

If you can raise the antenna higher, just 10ft can sometimes give better reception than 3dB more gain at the same height.

 

[jwt873]

I've got a jetstream JTB2. It's been up on top my 40 foot tower for over 7 years. I use it mostly for accessing repeaters located within a 30 mile radius of my QTH. It's 8 feet long with a claimed gain of 6 dB gain on 2 meters and 8 dB on 440.

It's not that bad as a general scanning antenna. I regularly use it for listening to Air, FRS/GMRS and LMR. I've even managed to score some DX in the 88-108 mHz broadcast band with it.

I would never recommend the antenna for dedicated non ham listening, but despite that, it does work surprisingly well for receiving out of band.

 

[ScannerDude244]

Your putting this on a scanner, are you going to use it to receive frequencies outside of the usable range of the antenna?

No just VHF 95% all that's all here. For the 700mhz i'm going yagi

 

[ScannerDude244]

The Jetstream antenna is resonant in the amateur bands and will be degraded some in the 150-156Mhz range. The gain figures for the Jetstream are way inflated, so its hard to say how the others will compare but I think they will receive better in the 150-156 range. The Laird antennas probably adhere to dB gain over a dipole and a 3dB difference will be very slightly noticeable on weaker signals.

If you can raise the antenna higher, just 10ft can sometimes give better reception than 3dB more gain at the same height.

I notice the fg1523 is little longer for 3dB gain?

 

[ScannerDude244]

I've got a jetstream JTB2. It's been up on top my 40 foot tower for over 7 years. I use it mostly for accessing repeaters located within a 30 mile radius of my QTH. It's 8 feet long with a claimed gain of 6 dB gain on 2 meters and 8 dB on 440.

It's not that bad as a general scanning antenna. I regularly use it for listening to Air, FRS/GMRS and LMR. I've even managed to score some DX in the 88-108 mHz broadcast band with it.

I would never recommend the antenna for dedicated non ham listening, but despite that, it does work surprisingly well for receiving out of band.

the build quality on these antennas are real damn good for the price, but I know I can do better with the dedicated VHF

 

[scanmanmi]

I'll take any gain I can get even though I don't trust them. Hurray on the coax.
"If I say I have a 24dB antenna, it means nothing, as I haven't told you what I referenced it to. It could be a 26.41dBi antenna (24dBd), or a 21.59dBi (also 24dBd!) antenna, depending on what my original reference was. The difference is 4.81dB, a significant amount. Most antenna manufacturers have gotten away from playing this game, but the reference will be different in different fields "
Taken from here What's the difference between "dB", "dBm", and "dBi" Wireless ISP FAQ | DSLReports, ISP Information