What is a Good 800Mhz Mobile antenna??

[mmckenna]

so what you're saying is you didn't have any issues with having a magnet mount on an antenna that requires a ground plane?

Right.
Don't confuse a DC ground with an RF ground.
A magnetic mount won't show a DC ground from the antenna base to the vehicle body (unless it grounds through the radio) This is OK.
To RF, the thin layer of paint is invisible. The capacitive coupling between the mag mount base and the vehicle body works just fine with RF and a good ground plane is provided.

I'd always recommend a permanent mount antenna as your best choice, but I understand that it isn't possible for everyone to do that. A good wide base magnetic mount might be your best choice. Just keep in mind that mag mounts can damage paint.

 

[N3JI]

Holes in body panels damage paint, too...

There is nothing wrong with capacitive coupling, in fact, my on-glass antennas are 100% capacitively coupled, and work extremely well (I have one for 800 MHz receive only, and another for the 900 MHz Amateur band, RX/TX obviously). I get into our 900 machine from 40+ miles out with 30W using it.

 

[K5MPH]

Hey thanks for all the info every one.
I will have to decide what one I am going to get.
I have tried cell phone antennas for the 800Mhz digital scanner but it seems like the gain just is not there it still cuts out.
I know on a lout of the police cars around here that I see they have the antennas that look like the
Laird Tech TRAB7603 so they must be working good.

The Laird antenna has the same gain as a cell phone antenna 3db I woulde'nt waste the. money I have been using a cell phone antenna for years and it does very well just make sure its the the one with the coil in the middle,just FYI good luck with you project............

 

[cmdrwill]

And to confuse the antenna issue: some 800 systems are simulcast with multiple transmitters and has the affect that your scanner is not receiving well."so I must need MORE gain".

So antenna gain on 700, 800 and even some 900 systems can be a trouble maker. Too much gain and the poor little scanner gets overloaded and can not figure out which signal to listen to. Then there is multipath too.

"the police cars around here that I see they have the antennas that look like the Laird Tech TRAB7603 so they must be working good." the police radios have much better receivers and Q /Q detectors that can sort out things better.

 

[N3JI]

...and they're also most likely to be in the town and close to the sites that they're using. Many of us listen to other municipalities from much farther away than a majority of actual users of the system. That's why I'm building a gain antenna for my home use.

But either way, those "pepper shakers" are the equivalent of a stubby antenna mounted on a car, and I have a hard time believing they are real 3 dB gain antennas. Also users of the system carry low-power portables, so the system has to be able to accommodate that as well, so those vehicle stubbies are probably just fine for that application.

In other words, if you live inside the area, and that's all you listen to, you don't need gain. I know I don't for my main system where I live, but when I want to listen to a system 30 miles away, it absolutely helps.

 

[DisasterGuy]

I invite you to do an actual use case evaluations, study patterns, etc before you compare an 800 phantom to anything. There is a reason they are specified in most public safety systems.

 

[rwier]

Best for 800 ONLY:

http://cdn.opentip.com/Electronics/...ltipolarized-Nmo-Antenna-Black-p-3259368.html

Good for 800 and "passable" on other freq's:

http://www.universal-radio.com/catalog/scanants/5896.html

My result of testing in my carport using the HP-1(E) analysis features. Your results may vary, lol.

 

[N3JI]

I invite you to do an actual use case evaluations, study patterns, etc before you compare an 800 phantom to anything. There is a reason they are specified in most public safety systems.

Quite simply, I have 30 years of RF experience and a solid working knowledge of physics to know the answer. ANY stubby antenna is a compromise, period. They work for the reasons I stated above. On 700/800, they're about as good a quarter wave (which isn't much taller than those anyway, and certainly not with gain, unless compared to hand-held antenna), but nowhere near as good as a real band-specific 3 or 5 dB whip, I don't care what the ads say. There are good reasons to use them, but that doesn't mean they are good for every application. If "stealth" is a priority, then yes, but anyone that is even remotely observant knows what those are. I listen to agencies far from where I live, so they won't fit well for me. They might be the best compromise, but still a compromise. And don't even try comparing a real whip on VHF/low UHF -- in the real world, they will out perform the stubby 6 days a week and twice on Sunday.

 

[DisasterGuy]

For the record, I would never use one in a stealth application. I will say however using a service monitor with one (one the same mount) it does out perform a quarter wave on 800 public safety. With that being said, you are correct that a 5dB raised feedpoint antenna will certainly out perform it. They are in fact better than the default quarter wave however. The UHF verson is pretty comparable to a quartwave. The VHF is a different story.