Previous post:

Next post:

Cellphone antenna booster sticker test and analysis

January 1, 2005

in All Articles,Cellphone reviews,Viruses / malware / scams

Introduction: What are cellphone antenna booster stickers?

You may have seen them: Little high-tech-looking stickers, something you stick on or near your cellphone’s antenna. Antenna booster stickers are supposed to improve your cellphone’s reception, leading to clearer conversations and fewer dropped calls. Here’s a photo of a package of one sticker brand (this is the brand tested for this article):

What is this document?

It’s a proper scientific test of antenna booster stickers. At the very least, it answers the question: Do cellphone antenna booster stickers work?

Everyone knows cellphone antenna booster stickers don’t work. Why are you doing this?

There are several reasons.

1) “Everyone” knows? Are you sure? And you say they don’t work, but can you prove it? Look at the number of companies who feature antenna booster stickers – a quick Google search gives plenty. Somebody’s buying. I want to warn people of such scams, of how the antenna stickers don’t perform as they claim.

2) During my research, I found some half-brained tests of the stickers. One example was a TV reporter talking on a cellphone, then slapping a sticker on his phone. He then said the signal seemed clearer, but wasn’t sure. This is a worthless test, not scientific, and is television media disrespecting their audience and dropping their own responsibility for intelligent analysis. I found no proper tests of antenna booster stickers. By “proper”, I mean scientifically legitimate. This, to my knowledge, is the only randomized, double-blind, placebo-controlled test of antenna booster stickers. It’s also probably the only cellphone test based on medical testing techniques.

3) I’ve had several conversations with people about these antenna amplifier stickers, and many told me they don’t work. “Great,” I said. “Can you tell me why? I’m running a definitive test of these stickers, and if you’d like to contribute, I’d love to get your thoughts.” At that point, people faded into the background. It was odd that people were willing to bash the stickers, but not willing to go on the record. Well, I finally spoke to the right experts on antenna theory and design. It’s not just me talking here. I ran the tests, but have people much smarter than me talking about antenna theory and radio physics, explaining scientifically why antenna booster stickers don’t work as advertised.

4) If supposedly honest retailers won’t take the responsibility to verify their products actually work, the job is up to us.

What do cellphone antenna boosters claim?

It’s advertised that cellphone antenna booster stickers improve cellphone reception and call clarity by boosting the signal reception of the phone. As advertised, the booster stickers can be shown to work by viewing the signal strength of a cellphone. When the sticker is applied, the signal strength should increase.

Cellphone antenna booster test preparation

1) Cut out five identical paper “pockets”. (We’re using paper because paper does not affect radio transmissions. This is also mentioned here.)

2) Buy two identical antenna booster stickers. Cut two tin-foil squares the same size as the booster stickers.

3) Insert the two booster stickers into one pocket each. (This is the test group. If they work, both antenna booster stickers should perform the same. We use two to make sure any measurements are truly consistent, and not the results of normal fluctuations in signal strength.)

4) Insert the two tin-foil squares into one pocket each . (This is a second test group. Does something like tin foil, containing more metal than a booster sticker, have any effect?)

5) Leave one pocket empty. (This is our “placebo”, or control group.)

6) Seal the pockets. Have someone else shuffle the pockets, and label them A, B, C, D and E. This is so the tester has no idea what was in each pocket, forcing all tests to be unbiased. The tester will have have no idea if what’s being tested are the booster stickers, tin foil, or nothing. Any opinions have been excluded from the test.

At the beginning of the preparation, here’s what we have, two booster stickers and two pieces of tin foil:

Here’s a close-up of one of the antenna booster stickers:

And here’s what we have at the beginning of the test, five randomized pockets:

7) And finally, gather the following equipment:

1 Verizon Treo 700p

1 Sprint Audiovox 6700

2 TracFone Nokia 1100b

Testing: Measure the effects of all pockets on multiple phones and multiple carriers

Drive to multiple locations around the city (I drove to nine different locations encompassing a forty-mile radius of my home), All locations were places where most of my phones’ signals were not at full strength. For each phone at each location, do the following:

1) Turn the phone on.

2) Hold pouch ‘A’ directly over the phone’s antenna. Wait for a minimum of ten seconds. Record the phone’s signal strength.

3) Keeping the phone in the exact same position, perform step 2 with pouches ‘B’ through ‘E’.

Results and analysis – How did the antenna booster stickers perform?

For those interested in the numbers (including the signal measurements for each phone at each location with each pocket), here is the raw test data in PDF format. The important bit is the lower half of the document as shown here, where I’ve averaged all the results so we can clarify what we’re looking at:

If the antenna booster stickers really work as advertised, they should be performing noticably better than our control group (B). They don’t. In three out of four cases, they perform worse. In one case (with the Treo 700p), the result is probably due to normal signal strength fluctuations – if the sticker was truly working, then the second sticker (C) would also have performed well. It didn’t. Also, the gap between first and second place was .11 signal bars, well within the top of the standard deviation bell curve. The antenna booster stickers showed no measurable improvement in signal strength.

We measured five tests on four phones at nine locations. That’s 180 data points. I would’ve liked to have more, but this sample set is still large enough to show a trend: The antenna booster stickers just don’t work. They don’t seem to affect the phone in any way, good or bad.

What do the experts say about cellphone antenna booster stickers?

I’m a technology columnist. I write about tech stuff because I like doing it. I like designing and performing tests. But I have no illusions about being smart. So I talked to smart people who know about antenna theory and radio science.

But first, let’s get information from the sellers themselves: Several websites selling antenna booster stickers reference these experts, testimonials and proof that antenna booster stickers work:

Seller claim #1: Joseph W. Fink, Ph.D. Mechanical Engineer
This guy says in this report, “The Internal Antenna does work and I do endorse the product and its technology.” My research turned up no such person. I found a psychiatrist by that name, but no mechanical engineer.

Seller claim #2: William Angle, “Engineer”, of the independent testing laboratories of Image Electronics.
I was unable to find any information about this man, his research or his testing lab. I emailed a booster sticker seller, asking for more detail on the information and proof presented so prominently on their website. They wrote back, saying (verbatim) “sorry, no help”.

Seller claim #3: Kodbins Ltd.
Some sites reference a case study and report by Kodbins, indicating antenna booster stickers work. The company has no website, and the only information I could find on them was at this page. Note that 1) they make the technology they’re testing, hardly an independent, non-affiliated test, and 2) the company did not respond to attempts at communication. They’re either hiding, or out of business.

Enough of this. Let’s hear from the real experts.

I interviewed two people: Matthew “Shadowmite” Fogle, and Sam “Spymongoose” Kidman. They specialize in cellphone reprogramming and custom modifications. The responses to the questions detailed below are combined answers from Sam and Matthew. For those who want technical information about how antennas work, and how cellphone booster stickers don’t, read on.

How does a cellphone antenna work?

“A cellphone’s antenna, or any radio antenna, is a resonant conductor that is tuned for a specific frequency or frequency range, much like how a tuning fork is tuned for a specific tone. When the tuning fork is struck, it vibrates at an exact frequency and emits sound waves. An antenna operates in a similar fashion, only in reverse. As electromagnetic waves come across the conductor (antenna), the conductor will resonate. In order to have a voltage, one part of this wave must be measured against a different part of the same wave. In the case of a radio antenna, the conductor takes the peaks of the radio waves and measures them against ground potential. This is where antenna length becomes important. In order to measure only the frequency of the radio waves that you want to listen to, the antenna must measure as close to either 1/4 or 1/2 the wavelength of the wave you want in order to get the biggest measurement of this voltage. If you look at a sin wave the biggest vertical measurement possible is from one peak to the peak on the negative side. By making your antenna conductor exactly 1/2 the wavelength you are trying to isolate you are effectively measuring a charge from one side of the wave while at the exact same time your radio’s chassis is grounded (to the negative terminal of your battery in the case of a cell phone) so you measure a charge in respect to ground, giving you the highest possible voltage that can be generated from that wave. The radio inside a cell phone then also further isolates the frequency and amplifies this voltage measurement and turns it into sound or data.

Certain frequency ranges have been set up for commercial use by your cell phone provider. Currently there are two primary flavors of cell phones: CDMA and GSM. CDMA uses two very separate frequency ranges, and GSM uses four. Although your service provider might use only one of these frequencies (or all four!) cell phone manufacturers have to make antennas that will perform equally well on all the frequencies available to the service provider. In order to accommodate all these frequencies, and to make the antenna small enough to fit inside a phone, the antenna is designed by a sophisticated computer program that calculates the twists and turns necessary to get the best reception with the space allowed. This antenna is made from etched copper on a piece of flexible plastic and then electrically attached to the sensitive radio in your cell phone. In essence, the antenna booster stickers are a lot like a real antenna, but not electrically attached to the radio.”

Explain how an antenna booster sticker would or would not work.

“Booster stickers will not work, and worse, may cause harmful interference.

The ‘antenna booster’ stickers that have been predominately advertised as a cell phone accessory that ‘will improve your signal’ and as one manufacturer has claimed ‘gives you the equivalent of an 11 foot antenna,’ certainly look like they have the same kind of technology used in modern cell phone antennas, and that may or may not be true. A longer antenna does not give you better reception when compared to one exactly tuned to the frequency you are trying to receive, and since it [the antenna booster sticker] isn’t electrically connected to the radio inside your phone then it shouldn’t matter anyway.

In the case that these stickers are actually designed to resonate close to the frequency of your cell phone then placement of the sicker would be vital. If the sticker was placed exactly right in relation to the cell phones antenna then it would act as a reflector, making it a antenna directional (think satellite dish), and the cell phone would have to be oriented in the correct direction to make a call. If incorrectly placed, the sticker would resonate at the phones operating frequency and become a source of out of phase waves that could either drown out the original signal, or cancel part of the signal, out making it effectively smaller than it would be otherwise, depending largely on the distance from the antenna the sticker is placed. Because your cell phone is a two way radio the sticker would also negatively affect the transmission properties of your phone by simultaneously adding resistive, inductive, and capacitive impedance to your outgoing signal (translation: smaller transmitted signal).

In the case that the stickers don’t resonate anywhere close to the frequency your cell phone uses, then the interference caused by the sticker would be greatly reduced. As harmful interference isn’t reported by the large user base that uses these products, I am led to believe that these stickers are simply decorative.

If the booster stickers don’t work, then how CAN you “boost” a cellphone signal? How do you make your own cellphone antenna? Can a cellphone signal be amplified?

“As an extreme, I have adapted a simple but potent antenna design and mounted it on a phone. The theory is that a straight antenna tuned for the exact frequency range used in that cell phone’s operation would work better than a small dual frequency antenna. In practice, the antenna performed admirably and greatly increased the operational capabilities of the phone it was mounted on. More recent phones I have owned have had stock antennas that performed just as well as the custom antenna I built.

More can be read here and here. Here is a picture of the first prototype antenna. Note that this is for a Verizon phone, and as such is the longest example of portable dipole antenna at just barely over 7 inches long. All other service providers will have antennas shorter than this.

Not to state the obvious, but simpler techniques might give an average user better reception.Observe just how much man-made and natural matter might be in-between your cell phone and a cell phone tower. Radio waves do not travel as well through concrete, iron, trees, stone, and dirt as well as they do through air. By making the radio waves go through as little of these obstructions as possible, your signal will greatly improve. For example, a cell phone will typically get better signal placed in a handsfree mount on the dashboard above the windowline rather than below the windowline, as there is less obstruction to the signal.”


I’ll make this very simple:

Based on my testing, and the antenna theory as presented by the experts, cellphone antenna booster stickers do not work as advertised.

Based on their marketing techniques, including the imaginary or unverifiable “experts” stating they work, it’s my belief antenna booster stickers are a scam.

It’s these pervasive small scams that really get me upset. They sneak in under the radar. They’re cheap and unobtrusive enough to insinuate themselves everywhere. Having a society where one can sell almost anything (without any proper verification of claims) gives an undeserved level of legitimacy.

In this case, the claims are far too good to be true. But the sad fact is that enough people are buying these types of products to keep companies successful for years.

Save your money.

Due to the popularity of this article, reader reponses are located on a separate page.

Previous post:

Next post: