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Cell Phone Booster

8334 Views 13 Replies 5 Participants Last post by  wallyp
I recently purchased a 2003 S430, and am very happy with it overall.

I do have a few things to do...

One of the minor problems was that my cell phone had poorer performance inside the car. A little investigation revealed the special heat-control window glass that also hinders radio performance, including cell phone and GPS.

Since my home has marginal cell reception anyway, I wanted better cell performance. I decided to try a cell phone booster, in this case a Wilson Sleek 4G-V (for Verizon). I installed the system today, and did a minor amount of testing.

The booster claims to improve performance in three ways: An antenna outside the car (and those windows!); an amplifier for reception; and a booster for broadcasting. (I am not an expert in this field, and may well make a mess of this, but will be happy to hear any corrections.)

The benefits of an outside antenna are obvious, especially for those of us who have the special glass in our cars. I do not like the antenna provided with the booster! I like the performance improvement, but I do not like the cable running out the rear door and across the roof. I hope to do something about that soon, namely using the rear-bumper antenna built into the S430.

The reception amp increases the signal strength, then wirelessly links it to the phone. The phone must be resting in the booster, basically in contact with it. Reception is the only part of the system that I have actually tested so far.

First thing that I learned - bars mean virtually nothing. I found how to measure signal strength on my new phone (Razr Maxx HD), and used that to decide whether the booster actually did anything.

Sitting in my drive, phone in the car as usual (no booster used), I saw fluctuating readings for 4G (or LTE) reception, such as -112dBm, -106dBm, -103dBm, etc.

The dBm scale is logarithmic, which means that 3 dBm doubles or halves the field strength. Lower numbers are better.

I slipped the phone into the booster, and the numbers instantly changed. I still saw fluctuating readings for 4G/LTE reception, but now the numbers were -93dBm, -91dBm, -89dBm, -87dBm, etc. This gave an improvement of -10 to -15dBm. A -10 dBm improvement is roughly 10 times stronger, a -15dBm improvement is roughly 30 times stronger. The reception bars on the phone display sometimes showed one more bar, sometimes not. The Command phone display never changed, even with 30 times the field strength.

I repeated the brief tests on the 3G network. Reception is reportedly better on the slower network, and the numbers supported that. With no booster in use, I saw readings of -88dBm and -89dBm pretty consistently. When I slipped the phone into the booster, the readings immediately went to -66dBm, -68dBm, -65dBm, -64dBm, etc. This gave an improvement of about 21dBm, or a level 128 times stronger on the 3G network. Again, the improvement was not shown by changes in the reception bars in the phone or car displays - one bar most of the time, occasionally two bars on the phone, none on the Command display.

If I were depending upon the bar display, I would have immediately packed the Wilson up and sent it back! The phones testing display showed a very different picture, and I am confident that the booster does what it claims for reception.

I haven't tested broadcasting, and am not sure that I can. The claimed improvement will be easier for the booster to achieve, though. From what I could find, a hand-held usually puts out less than 100mW. The Wilson puts out 1.8 Watts...

I pulled everything out of the phone compartment in the center armrest except for the puck and its holder. The puck, booster and cell phone fit nicely, and I can pop the small lid open to operate the phone if necessary. (I use the Voice Command system for the phone.)

Next project is to get the booster hooked to the car's antenna, so I can get rid of the tacky cable on the roof.

Comments welcome!

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Hehe Wallyp!

I'll send soon a picture of what's installed in my armrest, and then maybe you can give me some good advice on what to install.
BTW: my old Samsung phone works just fine from the car, but, of course no "hands free".

Thanks for posting such a good review Walley! I have a Sleek also and have been very impressed with it. Before spending time trying the other antenna, I would suggest seeing if you can find any specs for it. Most cell antennas are built only for the dual band frequencies so the 700 MHz LTE that your Sleek supports may not work nearly as well with the built-in antenna.

When you give it a try, let us know how it works!
Well, bogalot and Warren were correct in their concerns.

I bought a connector to fit the Sleek and installed it onto the antenna cable in the center console, and hooked the bumper antenna to the Sleek. Didn't work at all. I removed the trunk-mounted TeleAid/phone switch and hooked the antenna directly to the MB compensator. Success! Sorta...

Using the Wilson antenna on the Sleek, I saw a 25 dBm improvement in the 1x voice range, and 28 dBm in the 4G data range. This is a great improvement - over 500 times the original signal strength!

Using the stock MB bumper antenna on the Sleek, I saw a 24 dBm improvement on the 1x voice range, which is great - but the improvement in the 4G data range is only 9 dBm. This is better than nothing, but nothing like the improvement with the Wilson magnet-mount antenna.

A long conversation with a very helpful Wilson engineer didn't give me much hope. His opinion is that there is no way to improve the stock antenna - it simply isn't designed for the frequency range that I need. He suggested that I install a Wilson trunk-lip mount and antenna. Not too pretty, but better than the cable across the roof. No idea yet of the cost of parts.

Investigation will continue...
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...He suggested that I install a Wilson trunk-lip mount and antenna. Not too pretty, but better than the cable across the roof. No idea yet of the cost of parts.

Investigation will continue...
I'm guessing the tech was talking about an NMO trunk mount antenna like this one. The cost of the parts isn't going to be very much, under $36. The problem is that you have to drill through your trunk lid in order to install it! Not ideal, but it might be the best option.
Keep us Posted!

Inqiring minds want to know. I have been thinking about this project in my 03 also, mostly first about the cell phone position, and the Wilson Sleek Cradle parts. Have you checked into the details about the antenna? Specs required, etc. Perhaps a different antenna, factory for another car, a BMW or MB Shark fin would work by replacing the shark fin on the top, assuming the comm antenna is in that position in the modern ones.

Wilson does make a special cradle for 4G LTE devices, also assume special antenna required, to maximize boost, if your goal is to provide broadband into the car. It could be separate from the phone booster, and you may be able to hide all those components, or discreetly build them into the car.

Hopefully you're not trying to drive, talk, and surf the internet all at the same time :eek:! Let me know where you live and I will keep an eye out for you:)
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The Wilson engineer recommended their 304203 antenna, mounted on their 901101 trunk-lip mount (no drilling) and their 971119 adapter to hook the cable from the antenna to the Sleek. Total cost about $60 - which is almost half as much as I paid for the Sleek 4G-V including cable and antenna. This would improve performance very slightly over the standard Sleek antenna. It would also be a PITA to run the cable to the trunk - but I might be able to adapt the existing MB cable to the antenna.

I have discussed the antenna situation with the Wilson engineer, and with Keith (the MB cellphone expert). Both agree that the MB antenna is not tuned for the 700MHz LTE band. A later factory antenna mounted in the bumper might be a feasible idea. I plan to investigate what is available.

The Sleek 4G-V that I am using is the Wilson 4G system that is optimized for the Verizon system. They also have a 4G system optimized for AT&T and similar systems.

Wilson expects you to glue the cradle mount to the dash, so the phone is held vertically near the center of the car. Didn't want that. I have removed the plastic bits from the top compartment of the center console, and have the Bluetooth puck and its holder, and the Sleek cradle in there. At the moment, the power cords are running to a chintzy three-lighter outlet plus one USB outlet box on the side of the console. Don't like that, plan to change things to run the power cords inside the console.

Yep, I plan to "surf the Internet" and drive at the same time - the Google navigation system looks like it will be much better than the MB nav system. I do use the hands-free, voice-controlled phone and drive. I don't plan to read my emails and drive. :) To give you a better opportunity to avoid me, I drive a Desert Sand S430 in the North Atlanta metro area...
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Thanks for the info...

Thanks for the details...I'll be keeping an eye out for your posts. Like you I have an 03. I am thinking about using a ProClip mount for my iPhone, possibly the side console on the drivers side. It would be next to the accelerator leg, but also a good spot for the anticipated V1 Connection Display for a Valentine1 also on my wish list ;). I notice that there is often weak or intermittent data coverage away from the cities, even on interstate and state highways. That definitely interferes with Google maps or Navigation apps for Smartphones. I had also thought to bury a Verizon LTE puk in the same spot in my console, which requires an external antenna. Already trying to find a location to hide an external XM antenna, like you definitely don't want to have a trunk Hole...I am considering stripping my bumper cover for a respray anyway, so that would be a good time to insert an antenna. Let us know how it goes.
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I did some antenna testing...

Bare Razr Maxx HD inside the S430: 1x -92.0 dBm; 4G -119.8

Using the Sleek 4G-V:

w/ Sleek roof antenna - 1x - 65.7 dBm; 4G -93.2 dBm
w/ S430 rear bumper antenna & compensator - 1x 68.3 dBm; 4G 110.8 dBm
w/ S430 rear bumper antenna, compensator removed - 1x 76.6; 4G 100.1
w/ Sleek antenna under bumper 1x -71.2 dBm; 4G -96.6 -dBm

For those not familiar with the strength measurements, these are are from the cellphone. The measurements are field strength, and are logarithmic, so a 3 dBm change either doubles or halves the field strength. Higher values are better - e.g., -90 dBm is twice the field strength of -93 dBm, and -84 dBm is eight times as strong.

So I get about 32 times the field strength on the 1x voice frequencies if I use the Sleek 4G-V with the S430 antenna with the TeleAid switch and the linear compensator removed; and about 125 times the field strength on the 4G data frequencies.

This requires that you either get an adapter to hook the S430 antenna lead to the Sleek, or change the connector on the antenna lead. You also need a mini-UHF female/female adapter (also called a barrel connector) to connect the antenna lead in the trunk around the switch and compensator.

On the other hand, I can use the Sleek magnetic-base antenna, with the antenna lead run out between the rear door and the body, and across the roof.
This give a field strength 500 times as strong as the bare phone on the 1x voice frequencies, and the same improvement on the 4G data frequencies! A tuned antenna is a beautiful thing as far as performance is concerned, not so much on visual appeal.

If I use the car's antenna cable from the Sleek to the trunk, and then adapt to the Sleek antenna, I can put the antenna under the car, or I can run the cable out between the trunk lid and the body and put the antenna on the trunk.

I tried temporarily putting the Sleek antenna under the car, forward of the rear bumper. This gave a field strength strength 128 times the bare phone, four times better than the S430 antenna on the 1x voice frequencies, and on the 4G data frequencies, I saw about 256 times the bare phone strength and about double the field strength of the Sleek and the car antenna.

If I put the magnetic-base antenna on the trunk, I get the same 500 times better signal on both frequencies. Looks like I may have to get used to the appearance of the little stub antenna on the trunk...
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Thanks for the writeup and the analysis, wallyp!! :thumbsup:

Added to the W220 S-Class Encyclopedia and the How-To Guide for cell phones.
Wallyp, got a Photo?

Is it a stub(4" in or shorter) a club (6-12"), or a Ham Radio antenna(;))-Just a joke, they are like, 3-6 ft tall.

:bowdown:I bow to your antenna knowledge!
The Sleek antenna is a small, neat magnetic antenna that is 4.174" tall. The antenna is neat - I just don't like the loose exposed cable.

Photos and specs are here:
Mini Magnet-Mount Antennas | Store | Wilson Electronics
When you tried putting the 4" antenna in the bumper, did you keep it vertical? Laying out down will dramatically reduce the performance.

Edit: It also requires a ground plane so if you didn't stick it to something metal in the bumper while keeping it vertical, that would have also reduced the performance.
Yep - I just looked underneath and saw a steel bar running across the car forward of the bumper, and snapped the antenna to it, vertical but upside-down. Quick 'n' dirty test.

The biggest problem was that the antenna was forward of the aluminum structure in the bumper. It would be better to be outside of it, but that requires disassembly of the bumper cover. I think that the best approach would be to put a grounded steel sheet inside the plastic bumper to stick the antenna to vertically. Wilson says that the ground plane must be at least 3 1/2".
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