When you're looking for a good router these days it's tempting to leave single-band models by the wayside. Dual-band routers are faster and have that extra frequency that experiences much less interference. Why would you even consider a router that can only create a wireless network on one frequency? Perhaps because it is generally more affordable than a dual-band router?
This would be true in most cases, but the D-Link DIR-645 that we're reviewing here is not that cheap, with an average price of £65. There are decent dual-band routers available in this price range, even in the new 450mbps segment, including the TP-Link TL-WR2543ND and the Edimax BR-6675nD, even if the TP-Link router doesn't support both frequencies simultaneously.
There are actually a few reasons why a good single-band router would be an interesting alternative. First of all, many devices out there have a network adapter compatible with only 2.4GHz. Many laptops are equipped with a 150Mbit 2.4GHz card and many other mobile devices only support this frequency. Samsung only puts dual-band chips in some of its high-end devices, for example the Galaxy Nexus smartphone and the Galaxy Tab 7.7 and 10.1. RIM equipped its BlackBerry PlayBook with a dual-band chip. However, it can safely be said that the 5GHz band is still useless for many consumers.
Another problem with the 5GHz band is that, despite the significantly higher transfer rates, the range is in general not very good. Particularly if you have concrete walls and ceilings in your home, then the signal will quickly be reduced to almost nothing.
In other words, a single-band router should not be discarded right off the bat. However, D-Link still needs to justify why the D-Link DIR-645 carries the price tag of a dual-band router. In the course of this review you'll learn that the manufacturer does come with a pretty good argument. You can read the rest of D-Link DIR-645 preview on Hardware.info.