External Gain on PMP450 SM and AP...

Hi There,

I was just wondering how important it is to configure the External gain on the Access point and SM units and which values would be the correct ones to use? 

I found some values in the older configuration / user guides : Version 12.0.2 but I see the values got removed in later releases of the user guide so I'm not sure whether they're still valid or not?

PMP450 AP with stock connectorized Antenna : 17dBi
PMP450 SM with LENS :  5dBi

PMP450 SM with Clip   :  8dBi

PMP450 SM with Reflector :  15dBi

Thanks in advance,


Hi Steph,

For (5) GHz:

AP -  17 dBi – (60° or 90° sector)


8dB of Gain @ 5.4GHz

9dB of Gain @ 5.8GHz


5dB of Gain @ 5GHz

Reflector - 

14 dB of Gain @ 5GHz

Thanks for the info  , much apreciated. So I'm guessing it's rather important to get those values correct at installation ? 


Could someone give a brief run-down on why this is important to set correctly?

Sure... the 450 system operates with ATPC, or Automatic Transmission Power Control.  This means that the subscriber module (SM) will only put out enough Tx Power to achieve the target signal level at the Access Point (AP, or Base Station).

The SM relies on the operator to input the proper "External Gain" setting for the antenna being used in order to properly compensate the transmit power to achieve the desired RSL (Receive Signal Level) at the AP.

If the External Gain setting is set too high (i.e. you've made a mistake and put in 25 dBi gain instead of 15 dBi gain for the external reflector dish), then the radio will set its Tx Power artificially low, and may hit what it thinks is the regulatory limit for EIRP too early, resulting in a poor quality link.

If the External Gain setting is set too low (i.e. you set 5 dBi when the actual antenna is giving you 10 dBi gain), then the radio will be putting out more Tx Power than it needs to.  This can result in creating unnecessary interference for other devices (i.e. creates noise in the band).

Hope this helps answer your question...


Would this be the same for 3.65?

Also helps reduce DFS/LBT false detections.

@MohawkOne wrote:

Would this be the same for 3.65?

Yes, this applies to any frequency... in 3.65 it is especially important as there is a Listen-Before-Talk (LBT) requirement as well, which can affect the performance if this setting is incorrect.

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So, the numers are the same for 3.65? as 5?

17 ap?

15 reflector dish?

8 for lens?

No, the frequency affects the gain a great deal. 3.65 GHz and 5 GHz are different.

The integrated 3 GHz AP has a gain value of 17 dBi.

The C030045D901A (the standalone 3 GHz sector antenna) has a gain value of 16 dBi.

Per the spec sheet found on the PMP 450 SM webpage, you can see the gains.

For 3 GHz, the 450 SM itself is 8 dBi, and the reflector adds +12 dBi to that.

(Both the Lens and CLIP only apply to 5 GHz radios as noted in the spec sheet.)

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so, for 365.
450 sm with reflector dish should be on 20dBi?
and the 450 sm intagrated on 8dBi

Correct. For the original 3.65 GHz 450 SM, the internal gain value is 8 dBi.

The reflector dish adds 12 dBi (so in the software, the “External Gain” field in the software should be set to +12 dBi), and the total gain is 8 + 12 = 20 dBi.

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