The radios you mean the routers antennas ? Well I was just going to put the modem right beside router. Their not touching but its close.
wireless devices can be side by side as long as their frequencies dont overlap
Shielding, good soundcards have shielding because they tend to be placed next to 200W GPUs and the entire emf of a gaming desktop is way more than a modem/router. My desktop has 2 GPUs, dedicated NICs and soundcard but i dont get any sound distortion because the soundcard is shielded by a cover and around the chips itself. So if the modem isnt shielded than wifi might effect it but considering the power of wifi and the amount of watts consumed by the modem and the emf generated by it, it is more likely that wifi (max of 0.5W for consumer) will be affected by the modem being around rather than vice versa. Even the max of 1.5W for wifi is still less than a few watts used by the modem.It's the near-field stuff - Cable modems, along with DSL modems deal with RF before puking out TCP/IP bits - and it's the RF intermodulation artifacts that suggest a modest spacing between a modem and a Router/AP...
Welcome To SNBForums
SNBForums is a community for anyone who wants to learn about or discuss the latest in wireless routers, network storage and the ins and outs of building and maintaining a small network.
If you'd like to post a question, simply register and have at it!
While you're at it, please check out SmallNetBuilder for product reviews and our famous Router Charts, Ranker and plenty more!