When you’re conducting an RF survey for this purpose, keep one thing firmly in mind: The Z1900 is not an electronic alchemist, creating cell transmissions out of the pure ether. It only amplifies the signals. Thus, Spotwave recommends that you find a location with at least two bars of signal strength, which seems a good suggestion. I found that the Z1900 boosts reception well if it has even one bar to work with, though it really should be one bar that’s almost two, rather than no bars that might be one on a good day. You get the point.

The Bottom Line Spotwave Z1900 Spotwave, spotwave.com Very Good  8.2 criteria score weight Performance 9 30% Interoperability 9 20% Scalability 8 20% Setup 7 20% Value 7 10% Cost: $299 Platforms: Spotware reports hardware is intended for T-Mobile or Sprint phones, but testing suggests that it is carrier-agnostic Bottom Line: The Spotwave Z1900 is an effective cell-phone repeater that boosts signals in the 1900MHz band from marginal to superb. Surveying your site for the best reception point is the hardest part of installation: If you can't find somewhere on your premises with at least a bar or two of signal strength, then the Z1900 isn't going to be able to help you. About our Reviews and Scoring Methodology

After you’ve fixed the location of the NAU, you’ll want to place the CU. There are two broad guidelines to follow at this step. First, you’ll want to place the CU as near as possible to the people who will be using smart phones. That’s just common sense. Next, you’ll want to make sure there’s as much physical separation as possible between the units on the opposite ends of the cable. It might not make sense to you unless you’ve studied radio design, but placing them too close together will result in worse performance -- perhaps much worse performance.

I experimented with placement in my lab and found that I lost at least one bar of signal strength and as many as two if I placed the units right next to one another. Plan on at least 10 to 20 feet of separation to make sure you’re getting the most out of the Spotwave.

What is the most performance you can wring from the Spotwave? When I had everything properly set up, I went from two bars of signal strength to five. That’s a major improvement which meant using the smart phones changed from an adventure to a productive pursuit. Be aware, though, that the Z1900 isn’t as powerful as a cell tower: Once you get beyond 40 to 50 feet from the CU transmitter, the improvements quickly fade. (The company says that a single unit should cover a 2,500-square-foot building, but in my testing, I found that performance varied dramatically depending on walls, plumbing, and other architectural aspects.)

Spotwave went to great pains to tell me that the Z1900 is intended for T-Mobile or Sprint phones since both of these carriers concentrate their services in the 1900MHz band. The fact is, though, that the Z1900 is carrier-agnostic and boosted the indicated signal on an AT&T Blackjack by the same margin as seen on the T-Mobile and Sprint smart phones used in testing.

The bottom line? If your home or office is in an RF-challenged area and smart phone performance is important, then the Spotwave Z1900 can make things much better. If you get absolutely no signal, be careful: The Z1900 is not magical. But if you’re just looking for those last two to three bars of signal strength, though, the Z1900 could be a great investment. The hard part is figuring out the best locations for the NAU and CU: Once that’s done, the Z1900 just sits there, making life better for all the smart-phone users in the organization.