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Low profile/Phantom antennas

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mmckenna

mmckenna

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I was going through the photos on my phone and forgot that I had these. Figured this discussion comes up periodically, so here ya' go:

This is a Laird TRAB4703 470MHz - 490MHz low profile antenna. 3dB gain, or so they say.

The copper trace works out to about 5/8th's wavelength on those frequencies. Coil/capacitor for impedance matching.
So, wether or not this would actually get 3dB would be up for discussion. A straightened out 5/8th's wave will no doubt do better.

m6r8m98.jpg


mzxiDdx.jpg
 
mmckenna

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Looking at this photo, it made me realize that this was easy to take apart. Would have been pretty easy to cut the trace to fine tune one of these for a higher frequency. Too bad this one is above any frequency I'd need it for on UHF.
Our PD had a new car come in with this installed for the VHF radio (yeah, they forgot to spec the antenna) and I guess the installer just slapped on whatever they had handy. I've got a few other old antenna coils that I'll likely start taking apart to see what's in them as soon as I get my bench bandsaw up and running.
 
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N4KVE

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I use the 430-450 version of that antenna for my radio in the car. I also use the ISM version for 900 ham. Mounted on the trunk of my Impala, I am extremely happy with the results. Sometimes when I drive to Miami, I get 60 miles from the repeater. But mostly I use it in the county, where I’m never more than 25 miles from the repeater. Oh, the VHF versions of those antennas suck, so don’t waste your $.
 
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FFPM571

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I have used those and the shark fin style and been very happy with their performance. UHF and 800.. the football style phantom on VHF is mediocre at best.
 
mmckenna

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FFPM571 said:
I have used those and the shark fin style and been very happy with their performance. UHF and 800.. the football style phantom on VHF is mediocre at best.
Click to expand...

Yeah, I got a sample Larsen 700-800MHz blade antenna last year. I'm using it on a radio in my office. Works just fine.

I've never found anyone who liked the VHF low profile antennas. It's always cursing and either wanting to give it away or tossing it.
 
12dbsinad

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mmckenna said:
I've never found anyone who liked the VHF low profile antennas. It's always cursing and either wanting to give it away or tossing it.
Click to expand...

That's because you can't fit a VHF quaterwave into a little plastic fin. You also can't install square tires on your vehicle. Well, you can I guess...
 
W9WSS

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I've used various iterations of "low profile," or "transit-style" antennas. Usual round ones, shark-fin, and one of them that compels you change the lock-nut of your NMO mount where it's going to be utilized. I found them inferior to a common 1/4 wave whip, and the VHF "paint can" antennas terrible to the point where I sent it back to the place where I purchased it. I guess in the higher frequencies they work OK, and if you have very low clearances to drive through you don't have much choice unless you don't mind your whip(s) banging against the overhead door or ceiling where your vehicle is stored, or drives through.
 

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mmckenna

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I've used a few on 800MHz and they work as well as a 1/4 wave. But the difference between a 3" whip and a 2 1/2" tall low profile antenna isn't much.
I've got a Larsen demo antenna in my office. Good for 700 and 800MHz. It's clear, so you can see the wire mesh embedded in the plastic. Makes for a good broad band antenna. I'll try to remember to get a photo of it tomorrow.
 
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Project25_MASTR

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If I’m going NMO, I use the Maxrad/PCTEL wide band knob for UHF…430-480 MHz. Claims unity gain and frankly, it performs as as well as a 1/4 wave whip in all of my experiences. I actually think it works better in TDMA application (with a tinfoil hypothesis to match).

Can’t honestly say I’ve ever utilized a non-molded antenna for 7/800 MHz. Maybe I’ve had a customer on a whip as a temporary solution but always reinstalled a knob style (almost needed if you want 700 and 800 MHz).

Absolutely love using. The Laird TRAB450NP for control station applications…wish there was a version that covered 7/800 with the NGP option.

Sent from my iPhone using Tapatalk
 
jeepsandradios

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I use and have used the VHF shark fin antenna pictured above....but agree its not the best. If used for a certain purpose (VHF trunking) it works good for that. Even on our SAR repeaters I had very little trouble with it. With that said It wasn't worth a crap on simplex. I still run one on my new truck mainly to monitor C-C or something close to me, but all in all because i don't like 15 antennas sticking up on my truck ! All my UHF/700/800 are the Laird units pictured above and have always had decent success with them. Only issue i ever had was snapping one off with a snow brush in NY.
 
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