Google original pucks - antennas

[Jorabi]

I am adding an external sma connector to an original Google wifi point AC-1304 to connect it to a roof antenna TP-Link TL-ANT2415D 2.4GHz 15dBi Outdoor Omni-directional with a SkyRF 2.4G 36dB 4W amplifier. The puck has 4 internal antennae, 2.4 vert and horiz, 5 vert and horiz. I am looking for which motherboard connection I should use to get the 2.4 horizontal. I don't know by the internal antenna shapes which is which, and the motherboard is not marked.

Have not been able to find docs online. FCC docs show all the internals without descriptions. Any ideas?

 

[Tech Junky]

Any ideas?

Pick one, test it. Pick the other, test it. And keep the one that performs best.

 

[sfx2000]

Remember these are MIMO radios - so they provide both diversity as well as tx/rx for both radio chains - with the Google devices, there are two chains per band, hence the four internal antennas you have observed. Both antennas have to be used, otherwise the link will be unbalanced and performance will likely suffer.

Note that in the US - you're limited to +30 dBm Tx power on the input to the antenna for unlicensed use, so your 36 dBm 4 watt amplifier might not be legal for 20MHz DSS/OFDM channels.

 

[Jorabi]

I tested it and the contact that had the black 2.4 lead is great. I've been walking around the neighborhood to check signal lol. Now I just have to mount the connectors permanently and put the antenna on the roof (I jury-rigged it up high today).

 

[Jorabi]

Remember these are MIMO radios - so they provide both diversity as well as tx/rx for both radio chains - with the Google devices, there are two chains per band, hence the four internal antennas you have observed. Both antennas have to be used, otherwise the link will be unbalanced and performance will likely suffer.

Note that in the US - you're limited to +30 dBm Tx power on the input to the antenna for unlicensed use, so your 36 dBm 4 watt amplifier might not be legal for 20MHz DSS/OFDM channels.

I did not see your reply earlier. You might have read my response about testing. The two 2.4 antennas inside the puck are the same shape and mounted perpendicular to one another, so I thought they were just opposite polarities. So you are saying I need to use both 2.4GHz connections, but the 2.4 rod antenna only has one input. The signal is great (-40 dBm). Do I need to worry about the unused one? I only checked signal strength, not data speeds, if that is what you mean by performance.

 

[sfx2000]

So you are saying I need to use both 2.4GHz connections, but the 2.4 rod antenna only has one and the signal is great. Do I need to worry about the unused one?

you're leaving 3 dB of diversity gain by using only one antenna - and leaving quite a bit of performance on the table by only using the one RF chain, cutting throughput essentially in half.

If you are trying to cover a large area with WiFi - these are not the radios I would propose as a first choice.

collection.title | strip_html

www.alfa.com.tw

Good choices there - check the Amazon for pricing and availability

 

[Jorabi]

My hands are tied on the radios and antenna. This is a non-profit community center, not a home. I can use the existing 5 Google wifi points and the antenna/amp that were acquired for free, without buying anything new. The sporadic use of the outdoor areas does not require pristine performance, and it's all leisure activities. The indoor performance for the office and meetings is fine. I think I will try what I have, and if it is not good enough we'll go from there.

 

[thiggins]

It's good that you are trying to help a non-profit, but your methods may bring more harm than good.

Transmit power limit laws are there for a reason. You are not being a good Wi-Fi neighbor by blasting a 2.4 GHz signal all over the neighborhood and disrupting other networks.

I also hope your roof-mounted antenna has proper lightning protection.

 

[Jorabi]

I said 'neighborhood' as shorthand. I was really just walking to the far reaches of the property then to the next property which is an office complex. By the time I get to the nearest office building the signal is weak.

But are you talking about the output levels regardless of signal strength? The dBm ratings or the watts? Should the dBm ratings of the radio (?), amp (36), and antenna (15) be added together to compare to the limits? Should max ratings be used or operational levels?

I found the amp on Amazon and the FCC sites. The FCC shows that it's approved for unlicensed use. Why would the FCC approve it if 30 dBm and x watts are the limits?

https://www.amazon.com/dp/B07MCNW79M/?tag=snbforums-20

FCC ID 2AQVQHS242036T1 Wireless USB Adapter by Suzhou Huashi Wireless Tech.Co., Ltd.

FCC ID application submitted by Suzhou Huashi Wireless Tech.Co., Ltd. for Wireless USB Adapter for FCC ID 2AQVQHS242036T1. Approved Frequencies, User Manuals, Photos, and Wireless Reports.

fccid.io

Note, the FCC documents refer to a package of USB client radio and the amp. They must be sold together somewhere.

P.S. There was a lightning arrestor with the antenna. I will install it together and ground it.

 

[thiggins]

Just because Amazon sells it, doesn't mean it is FCC compliant. I've found routers listed that have no FCC ID.
I've downloaded the test report for the product you linked. It is a USB adapter with an outboard amplifier module. The module itself does not have an FCC ID number.

The test report says peak conducted power is 30 dBm (1W), not the advertised 36 dBm.

The other thing about boosting transmit power is that it usually isn't helpful in extending range because client devices don't have equivalent power. So while STAs may "hear" the AP, the opposite may not be true.

A better approach is to use higher gain antennas on the AP. However, the higher the gain the more directional the antennas. But if you are trying to cover a focused area like a courtyard, that will be fine.

@sfx2000 is correct. By using only one channel, you'll be giving up potential receive gain. You'll also mess up link rates. The radio thinks it has two antennas and adjusts its link rates accordingly. So it will use a higher MCS, that isn't really available because the two RF chains are not equal.

Consider putting out the call to non-profit donors for a little funding to get proper outdoor APs as @sfx2000 suggested. EnGenius also has many relatively inexpensive models to choose from.

 

[Jorabi]

So since the peak output power from the FCC tests was 30, I should assume the 36 was just for marketing? The FCC would fail the package if part of it violated regulations, no?

I would still like to know about my other questions though. Should the radio's gain and the antenna's gain be added to the 30, which would then certainly violate the law? Or does it not work that way. Is there an inexpensive way, like a phone app, that I can measure total output power under real world conditions?

Bottom line, my own testing shows it meets their needs in all the relevant spots. As long as I am not violating any laws, are you satisfied with me leaving it as-is, regardless of all the ways I could make it even better? In this environment, I would rather go with "good enough". (I realize those words are cringeworthy in a forum like this lol.)

 

[thiggins]

So since the peak output power from the FCC tests was 30, I should assume the 36 was just for marketing? The FCC would fail the package if part of it violated regulations, no?

Correct. But it's important to note that the test was for the combination of the USB adapter and outboard amplifier. We have no information on the TX power of the USB adapter itself. But I would guess it is negligible. Could be that there is no inboard Tx amp at all.

I would still like to know about my other questions though. Should the radio's gain and the antenna's gain be added to the 30, which would then certainly violate the law? Or does it not work that way. Is there an inexpensive way, like a phone app, that I can measure total output power under real world conditions?

The test referenced above is conducted power, or as @sfx2000 pointed out:
"Note that in the US - you're limited to +30 dBm Tx power on the input to the antenna" (emphasis mine).
No, there is no inexpensive way to measure RF power, either conducted or radiated. Believe me, I've tried to find one.

Give that, and the fact that you are applying an amplifier to a product already designed to meet FCC limits without an external amplifier, you could be violating regulations. You also could be overloading the amplifier input or driving it to saturation.

I suggest you do some throughput tests to see if you really have an improvement. Higher signal doesn't always mean better throughput for the reasons already given.

"Good enough" is fine. I'm not a perfectionist. But do the throughput tests to see if you really are getting the improvement you seek.

 

[LilyRoss]

I am adding an external sma connector to an original Google wifi point AC-1304 to connect it to a roof antenna TP-Link TL-ANT2415D 2.4GHz 15dBi Outdoor Omni-directional with a SkyRF 2.4G 36dB 4W amplifier. The puck has 4 internal antennae, 2.4 vert and horiz, 5 vert and horiz. I am looking for which motherboard connection I should use to get the 2.4 horizontal. I don't know by the internal antenna shapes which is which, and the motherboard is not marked.

Have not been able to find docs online. FCC docs show all the internals without descriptions. Any ideas?

you can try different products