Cell Phone antenna boosters

[sickstan]

I've seen these "cell phone antenna boosters" for sale. They are essentially a clear piece of plastic with a disconnected pattern of what appears to be conductor (film copper?) that's placed between the battery and the phone "as close to the antenna" as possible. I can't think of any way this would work, but they are dirt cheap. Has anyone actually used one?

 

[uruk]

Actually, I think they are a scam. In order to boost antena performance you need to amplify the signal in some fashion.
Antenas ar usually cut to a specific length depending on the wave length of the intended carrier frequency bandwidth. adding length to it does not always help. even then the metal conductor has to be electrically connected in some fashion.

 

[Jas]

Not totally on topic, but kind of related....

I couldn't figure out why my celphone had an external antenna, when the one pictured in adverts down in the states, didn't have one.

Turns out, the celphone doesn't need external, the internal antennas are just as good. However, the phone company discovered that they got fewer complaint about service and reception when the fake antennas were on the phone, because people THOUGHT that they worked better.

As a result, all of the celphones sold by Telus have fake antennas.

 

[DangerousBeliefs]

Not totally on topic, but kind of related....

I couldn't figure out why my celphone had an external antenna, when the one pictured in adverts down in the states, didn't have one.

Turns out, the celphone doesn't need external, the internal antennas are just as good. However, the phone company discovered that they got fewer complaint about service and reception when the fake antennas were on the phone, because people THOUGHT that they worked better.

As a result, all of the celphones sold by Telus have fake antennas.

Not true for most cell phones.... most have an antenna, that when raised, provides optimal reception with the least battery drain.

It's just that most of the time, newer cell phone techology works so well that we don't notice any loss in strength in a large urban area.

 

[Captain Trips]

I've seen these "cell phone antenna boosters" for sale. They are essentially a clear piece of plastic with a disconnected pattern of what appears to be conductor (film copper?) that's placed between the battery and the phone "as close to the antenna" as possible. I can't think of any way this would work, but they are dirt cheap. Has anyone actually used one?

I haven't bothered to use them, but I understand they work by sympathetic vibrations. (Electromagnetic, that is, and NOT woo-woo.) Remember the days before cable? TV antennae would have multiple elements. Only one pair was actually connected to the wires. The other sets would absorb and reradiate the signal, on a tuned level to increase the effectiveness of the main elements. Also, with rabbit ear antennae, moving your hand around them would affect the signal. Well, I understand these "boosters" work in a similar manner. It actually does make sense, and is quite likely possible that they do work. Of course, as I said, I have never used them so don't know from personal experience, but the science (electromagnetic physics) is there to support the theory.

 

[MRC_Hans]

Re: Re: Cell Phone antenna boosters

I haven't bothered to use them, but I understand they work by sympathetic vibrations. (Electromagnetic, that is, and NOT woo-woo.) Remember the days before cable? TV antennae would have multiple elements. Only one pair was actually connected to the wires. The other sets would absorb and reradiate the signal, on a tuned level to increase the effectiveness of the main elements. Also, with rabbit ear antennae, moving your hand around them would affect the signal. Well, I understand these "boosters" work in a similar manner. It actually does make sense, and is quite likely possible that they do work. Of course, as I said, I have never used them so don't know from personal experience, but the science (electromagnetic physics) is there to support the theory.

Sorry, but no.

In THEORY, this could be right, but it would require the thing to be placed in EXACTLY the right position relative to the antenna. With these wavelengths this is within a millimetre or two, NOT just "as close to the antenna as possible"

AND even if you did place a director (that's the name of such an antenna element) just right, the "boost" would be at the cost of directional characteristics. A cell-phone antenna needs to be as multidirectional as possible. Any passive boost can ONLY be made at the cost of making it more unidirectional.

So, these devices, no matter how little they cost, are way too expensive . A value for money calculation would always result in a divide by zero error.

Hans

 

[uruk]

The other sets would absorb and reradiate the signal, on a tuned level to increase the effectiveness of the main elements.

The problem with this is that the reradiated signal would be much weaker than the original signal to be of any use.
I've recently open up a TV antenna booster, and indeed all the elements are electricly connected via a selector switch.

 

[MRC_Hans]

The core of the matter is, you can only boost a signal in two ways:

1) You can concentrate it in one (or a few) direction(s). This means that it will be weaker in all other directions.

2) You can amplifiy it. This requires electronic circuitry and a power source.

There is no such thing as a free lunch.

Hans

 

[TillEulenspiegel]

I've seen these things in two flavors. One form is as a passive (re) radiator, where the film takes part of the signal and emits it. The curve is as one would guess, decidedly negative . The thing actually leeches signal and radiates it at much smaller levels then it is driven at. The other method is as a ground plane , this makes much more sense but the way it is affixed in the phone is parallel and a ground plane is ideally 90 degrees at the perpendicular. You've probably seen CB radio antennas on a house with four antennas parallel to the ground a one vertical central antenna in the center. The ground plane gives the radiated signal a "floor" to "push" against and the half of the signal that would be normally directed at the ground is not given a path , so less wasted signal. Unfortunately the dimensions for a ground plane at the mobile phone frequencies is about 8"x 8" to 12"x12", much more then the matchbook sized thin films that are sold.

A line from one seller of these devices "No passive antenna such as this can function as a booster! "
Bad science.

 

[epepke]

The core of the matter is, you can only boost a signal in two ways:

1) You can concentrate it in one (or a few) direction(s). This means that it will be weaker in all other directions.

2) You can amplifiy it. This requires electronic circuitry and a power source.

There is no such thing as a free lunch.

Hans

Now, I don't think these antenna boosters work. However, there's a third thing you can do, and that is to trim the antenna, with an inductor and/or capacitor, so that it behaves electrically more like a 1/4 wave antenna. This doesn't actually "boost" the signal, but it reduces the waste of power needed to drive the antenna.

This I think is the appeal of these things; they look sort of like inductors. But it's probably a scam, as putting one behing the battery is unlikely to have an effect.

 

[MRC_Hans]

epepke: You are right, but I should be very surprised indeed if the antennas of a super-advanced piece of communication equipment like a modern cell-phone is not already perfectly trimmed.

Considering the harsh requirements for battery endurance and coverage, I cannot imagine that there is anything left to trim.

Hans

 

[roger]

Given how much competition there is in that marketplace to provide better reception, why on earth wouldn't the manufacturers have already included this functionality in their phones? If not in there $50 dollar phones, at least in their top of the line $300 dollar lines. Any VP of technology would be tossed out on her ear in a second if she ignored such a simple, cheap way to improve the product.

 

[MRC_Hans]

Yeah, that's like those mileage boosters for cars, heheh. If there was any chance they worked, they would be factory mounted .

Hans

 

[epepke]

epepke: You are right, but I should be very surprised indeed if the antennas of a super-advanced piece of communication equipment like a modern cell-phone is not already perfectly trimmed.

Considering the harsh requirements for battery endurance and coverage, I cannot imagine that there is anything left to trim.

Well, there could conceivably be something left to trim, but the battery itself is a big lump of metal with significant inductance in the frequencies we're talking about. I seriously doubt that some curliques next to it would have any effect whatsoever.