The R8500 router is a tri-band router. Why do I only see four antennas?

[NightHawkNewbie]

Why do I only see four antennas?

[netwrks]

Is there e reason why you can't ask all your questions in one post? Maybe you should look at the manual. 

[ElaineM]

Hi @NightHawkNewbie,

Welcome to the community!

The router is tri-band, which means that it has three WiFi bands: one 2.4 GHz band and two 5 GHz bands. The router has four external antennas and four internal antennas. The four external antennas are used for one 2.4 GHz WiFi radio and one 5 GHz WiFi radio. The four internal antennas inside the router are used for the second 5 GHz WiFi radio.

Hope this helps.

[mbcole]

What specific band uses the internal, rather than the external, antennas?

[ElaineM]

@mbcole

Both 2.4GHz & 5GHz Low Band (Ch 36~48 + 52~64) (UNII- 1 & 2A) uses Active Antenna  (Only External Antenna).
Internal 5GHz High Band (Ch 100~140 & 149~165) uses Passive Antenna.

[mbcole]

Which band is recommended for best short-distance wireless performance?

[ElaineM]

You may use 5Ghz signal.

Less interference on that band and it's now commonly used for that reason.

[mbcole]

I thought the 5GHz HIGH band is good to use for BEST performance (and wireless AC). 

So why is that band only using the passive internal antennas?

[ElaineM]

Let me forward this question to our engineering department for an accurate answer.

I will get back to you shortly.

[ElaineM]

Update:

The 5GHz high band is usually the band for best performance, however, the 5GHz low band is actually better on R8500. This is due to new FCC regulations which allow for an increase in maximum output power for the 5GHz low band. Also, there is a new FCC rule that decreases the maximum output power for the 5GHz high band.

[mbcole]

Wow. I didn't expect that.

But if the new FCC rules restricted the maxiumum output power on the 5GHz high band, then how come the active antennas weren't used with that band? Wouldn't that have "helped" performance a bit?

[ElaineM]

Yes, we could have used active antennas for the 5GHz high band but most mobile devices perform better wirelessly on the 5GHz UNII-1 (Ch 36~48)  compared to the 5GHz UNII-3 (Ch 149~165). This is one of the reasons why we decided to implement the active antennas on the 5 GHz low band. Using active antennas on the 5GHz low band also allows us to maximize the range on this band.

In the 5GHz High band, mobile devices wireless performance is poor and are used mainly for Close and Mid-range usually for secure activities or to transfer huge amount of data.