Wifi Frequency - Antenna or Access Point

After recently buying an outdoors access point from tp-link I realised that it is a 5ghz device (built in antenna).

For one of my access points I have purchased a external antenna, which leads me to my question - is the frequency determined by the access point or the antenna? As I also wish to have a 2.4 ghz network for mobiles.

-
All of the equipment has to support every frequency it operates on. – David Schwartz May 16 '12 at 0:00

The frequency is usually determined by the access point. I suppose it's possible to have an antenna that's optimized for 2.4GHz or 5GHz, but usually the antenna should be fine handling both.

To be a bit more specific, the frequency is determined by the technologies the access point is trying to support:

A - 5Ghz, always
B - 2.4Ghz, always
G - 2.4Ghz, always
N - 2.4Ghz or 5Ghz, depending on what the client and access point both support.
-
Thanks for the help - I thought this wa the case. – Daniel May 16 '12 at 6:18

An antenna is just a passive hunk of metal. The size and shape of that piece of metal may make it better at radiating radio-frequency (RF) energy at certain frequencies, but it doesn't change the frequency of any of the RF energy that's flowing through it. You can't turn a 2.4GHz radio into a 5GHz radio just by attaching a different antenna to it. If you attached a 5GHz-optimized antenna to a 2.4GHz radio, you'd just end up with a less-than-ideal antenna hooked up to your 2.4GHz radio.

The frequency of a radio is determined by how the radio circuitry is tuned (quartz crystal oscillators and related components in the radio circuitry). So since your 802.11 radio is an internal component of your AP, it's fair to say that it's the AP, not the antenna, that determines the frequency of your network.

-
Thanks - That gives me much more information than I could find :) – Daniel May 16 '12 at 6:20