DIY cell repeater?

May 23, 2006 9:08 AM

Can Plutor make his own cell phone repeater?

Posting this as a proxy, as Plutor just asked a question yesterday:

"I moved into a new condo this weekend. Sadly, despite the full cell phone signal I get on the sidewalk just outside, I get nothing at all inside the building unless I stand very close to the windows. There's supposedly no lead paint in the building. My wife and my friends have the same problem. What can I do to remedy this situation? I don't want to spend the several hundred dollars on a cell phone repeater. Is there a cheap indoor-to-outdoor antenna I can use? Can I make my own repeater?"

posted by splatta to technology (13 comments total)

What you're looking for is a passive repeater. Wireless networking hackers use them all the time to route signals where they need to go. Googling for 'passive repeater cell' seems to get a ton of hits, like this one that has a large antenna on the outside, and a set of small ones for the inside.
posted by zsazsa at 9:20 AM on May 23, 2006

Any powered or active repeater would be a against the law. The cell company has an exclusive license to operate transmitters on those frequencies.

[Just in passing, lead paint has nothing to do with anything. At these frequencies, all matter reduces signal intensity. The more mass, the greater the attentuation.]
posted by Steven C. Den Beste at 9:26 AM on May 23, 2006

zsazsa, do those 'passive repeater' antennas really work? My guess has always been that they are more gimmick than practical. Could you post a review link, or tell us your experiences?
posted by bug138 at 9:39 AM on May 23, 2006

Wow, that passive repeater looks like an excellent deal if it works. I'm with bug138: does anyone have any first-hand experience with these?
posted by Plutor at 9:41 AM on May 23, 2006

Well, Googling "Do passive repeaters work" brings up a lot of results that suggest "kinda" as the answer, or "kinda but not really," depending on your level of optimism or pessimism. This one explains things pretty well without falling too far on either side of that divide.

Of course, I have no idea, I don't even own a cell phone, I just was bored at work.
posted by OmieWise at 9:56 AM on May 23, 2006

Have you updated the tower location database on your phone lately/ever? Some providers have a * number for this, others you have to call customer service first. (I was just looking at this yesterday and it looks like Sprint, at least, requires a phone call.)
posted by Lyn Never at 10:08 AM on May 23, 2006

No, I haven't. Googling hasn't revealed anything helpful, either (I have a Nokia 6682 with Cingular).
posted by Plutor at 10:49 AM on May 23, 2006

In a former life I was responsible for cellular coverage and have some professional knowledge that may help.
It sounds like that a passive repeater may work for you Plutor, but to be sure here's the criteria for success with them
First, the outside antenna should be pointed at the correct cell phone tower and have a good signal. Second, the inside antenna should be within a couple hundred feet of the outside antenna. Third, the connecting cable between the antennas should be as low loss as possible (hint: the thinnner and more flexible the cable, the higher the loss). Fourth, the inside antenna should be in the place where you need inside coverage (the repeater may not solve the coverage problem outside of the immediate vicinity of the inside antenna).
I've had good success when implementing a system that met all the above criteria.
Hope this helps ...
posted by forforf at 11:02 AM on May 23, 2006

Steven C. Den Beste writes "lead paint has nothing to do with anything. At these frequencies, all matter reduces signal intensity. The more mass, the greater the attentuation."

Reinforced concrete is your enemy here. The rebar acts as a fairly effective faraday cage. If your floors/roof were poured on a steel deck that will worsen reception too. Also if your building is stucco'd the stucco wire is a factor as well.

I know nothing about passive repeaters but John DeArmond in OmieWise's link knows his stuff.
posted by Mitheral at 11:15 AM on May 23, 2006

As an alternative idea, does your phone support Bluetooth? I got poor reception in my bedroom at college, so I just kept my cell phone on a windowsill and used a Bluetooth headset. It solved my need to be perched in a windowsill to talk, and also made for a more 'natural' feeling call.
posted by fogster at 11:15 AM on May 23, 2006

The repeater shown in zsazsa's link will probably disappoint you. My neighbor and I recently went through several options to provide him with better reception inside his house and that repeater was one that failed miserably.

FWIW, he picked up a Solid Signal amp/repeater on eBay for a couple of hundred dollars and it works like a charm.
posted by forrest at 11:17 AM on May 23, 2006

Similar to the bluetooth headset (minus the inherent toolness of them - no offense fogster) you could try this pretty neat gizmo that connects your cell phone to an "old-fashioned" landline-style phone. Granted, it's a bit on the expensive end and the reviews aren't too hot.
posted by redsnare at 1:33 PM on May 23, 2006

Ahem, the reviews.
posted by redsnare at 1:34 PM on May 23, 2006