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Laird Technologies TRAB 4503 vs Laird AB450 for Mobile


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Anyone care to critique/compare these 2 antennas for mobile?  I have the 450 1/4 wave on SxS and planned on another for the pickup.  Have been advised that the 4503 is 3 - 5db gain while maintaining a low profile (3.5").

 

The Laird description.

 

"The Phantom low visibility antenna has a wide bandwidth and low radiation pattern for superior results."

 

Thanks.

 

 

 

 

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Can highly recommend the 4503. We have placed one on the roof of a truck with a magnet mount and it performs above expectations. Have talked back to our repeater with a 15 watt mobile at 52 miles point to point with it. Don't let the size fool you with this one! Would buy it again without hesitating.

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A UHF Phantom antenna is NOT 3-5 dB gain. At best, it's a zero gain.  You'll see them advertised as a 2.5 gain dBi (Gain over an isotropic) - which is Zero dB gain. Some people decide that 2.5 dBi rounds up to 3 dBi for advertising purposes, and since most people don't know or care to figure out what the difference is - it means that dBi ratings sell more antennas.

 

If you want a true Gain antenna in UHF, you're going to need something taller than 1/4 wavelength.

 

That said, the Phantom antennas are decent enough for what they are, but don't expect any miracles.

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Not looking for high gain or the ability to shoot at far distant repeaters but wouldn't mind something a little better than 1/4 wave.  Been told by a qualified source that the helical would Phantom will outperform the 1/4.  And according to Laird the Phantom has a "low radiation pattern" so I'm thinking it might be ok for simplex and trail riding similar to the pattern of the 1/4.  But I've been mistaken before. 

Guess I'll try both and see if I can tell a difference (seat of the pants).  I like that the Phantom is a couple inches shorter to the roof of my UTV.

 

Thanks.

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... the Phantom has a "low radiation pattern" so I'm thinking it might be ok for simplex and trail riding...

You have mentioned the suitability of an antenna for repeaters and simplex as though the two things are inherently different.  Well, to some (very tiny) extent they are, in that with a repeater your transmit and receive frequencies are 5mHz apart, so there is a small degree to which an antenna might be tuned differently depending on whether the main use was simplex (tuned right on frequency) or duplex (somewhere between the Tx and Rx).  But, that is really pretty insignificant.

 

On the other hand, an antenna's  radiation pattern can make a difference depending on the physical relationship between two stations talking simplex,  or a station talking to a repeater.  But, since many repeaters are actually located pretty close to the ground, like on roof tops, and two stations on a jeep trail could be several hundred vertical feet apart, you can't really say any particular "gain" pattern is better for one or another.  However, as others have noted, a simple 1/4 wave may well be the best compromise, especially in a situation where both stations are in motion.

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I am curious to this antenna as well. It would be well suited to the offroad environment if it works well.

My friend has a metal roof on his utv and we went with the regular Laird 1/4 wave as it was a third of the price.

We might have to go with this one if he breaks it tho because he got his nickname "Flipper" for a reason.

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BTW, I honestly don't understand why you just don't go with a simple 1/4 wave NMO mount antenna. They are dirt cheap, and easily replaced. A fiberglass antenna, no matter how rugged, will shatter if it hits a low hanging branch, overhead rocks, or even the ground (for flipper). A simple metal 1/4 wave will just bend over and can be straightened out in seconds (or replaced with a spare).

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BTW, I honestly don't understand why you just don't go with a simple 1/4 wave NMO mount antenna. They are dirt cheap, and easily replaced. A fiberglass antenna, no matter how rugged, will shatter if it hits a low hanging branch, overhead rocks, or even the ground (for flipper). A simple metal 1/4 wave will just bend over and can be straightened out in seconds (or replaced with a spare).

 

That's what I've done.. simple Laird AB450.  Comment to me was "now if you get a good antenna like TRAB4503"...

 

And Jones explained what I was told about the 4503 "That stubby antenna is more than likely a 5/8 or 3/4 wave normal mode helical antenna.  It would have not as much gain as a true 5/8 wave, but due to a low-angle "flattened doughnut" radiation pattern, it would have slightly more gain than a 1/4 wave antenna.  ... theoretically."  5/8 helical is what I was told.

 

Have to find just the replacement whip for the 450 to carry with.  

 

All good stuff guys.  Glad I asked.

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...And Jones explained what I was told about the 4503 "That stubby antenna is more than likely a 5/8 or 3/4 wave normal mode helical antenna.  It would have not as much gain as a true 5/8 wave, but due to a low-angle "flattened doughnut" radiation pattern, it would have slightly more gain than a 1/4 wave antenna. ...

And, that is true. However, the issue I was raising was, is a flattened radiation pattern really the best choice for your application. If you are in hilly our mountainous terrain  (you are in Nevada, right) then a flattened pattern may not be the best choice.  However, in the end, the small differences in radiation would probably make no discernible difference. That is why I'd go with the lowest cost solution - for this application.  Now, if you were a delivery driver in Kansas, maybe a hi-gain antenna would make a real difference.

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That antenna along with many others on the market, reminds me of something I heard about fishing lures: they're designed not so much to catch fish, but to catch fishermen.

 

Generally speaking, the shorter the antenna and the wider its bandwidth, the less gain it has. A better way to state it is the more loss it has.

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So the flattened pattern is a characteristic of the cone, but not the 1/4 wave?  Aha moment.

Yes. Put very simply, no antenna has any gain as they are passive devices, they simply radiate. True gain requires amplification. What is called gain in an antenna is really apparent gain. That is, the the strength of the received signal, either at or from the remote radio is compared to the signal received using an hypothetical lossless antenna that radiates or receives signals equal from all directions - above, below and from the sides.  If an antenna's design favors signals transmitted or received from some particular direction, or directions, then at the same time it is reducing the signal transmitted or received from some other direction.  The result of changing the radiation/reception pattern results in signals from/to some direction(s) being stronger than from others. Thus the apparent gain.   Your doughnut radiation pattern favors signals from/to the sides and reduces signals sent/received vertical.  

 

It is a little bit like adding a lens to a lamp. A bare bulb (theoretically) radiates light in all directions. But, by placing a reflector behind the bulb and a lens in from of the bulb to direct the light, you will have much more brightness in the direction the lens faces, and much less light behind the reflector. But, the actual light output from the bulb remains unchanged.  In fact, Yagi design directional antennas use elements with those exact names: directors and reflectors.

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