PTP550 high gain antenna?

I'm looking at using the PTP550 for some long-range shots, up to about 18 km. So it'll need an antenna of at least 29 dB gain on each end, maybe more for best performance. What dish antennas mate well with it, and are suited to a rather rough (icy, windy mountains) climate?

Depends on where you base? For FCC region, PTP 550 is not allowed to use 29dBi antenna per FCC grant we received due to EIRP limitation.

I'm in the US.

1) Are you saying that the type acceptance prohibits the use of a higher-gain antenna? (Most PtP radio makers don't set a limit on the antenna, but the installer has to stay within the EIRP limit that the radio is approved for on any given frequency. That is based on either the frequency limit or the OOBE limit, depending on how clean the radio is and how close to the band edge it is.)

2) What EIRP would be allowed with a 29 dB antenna?

3) What 29 dB antennas are easy to set up and mount the PTP550 on or near?

Per FCC approval of PTP 550, the antenna gain of connectorized antenna for PTP 550 is limited to 22 dBi. Meaning if using 29 dBi antenna, a 7 dBi in-line loss need to add from the radio output to antenn input. 

PTP 550 provide N-type connector in connecotrized version.

AllenYu, I am actually quite expert at FCC rules, and what you say makes no sense at all! FCC type approvals never specify an attenuator in line with the radio. They do specify a maximum EIRP for a given frequency and emission mode, but that is normally accommodated by having the radio lower its transmitter power. So there should be, in the US firmware, an EIRP cap table by channel and bandwidth, and the connectorized radio should ask what the antenna gain is. The radio then subtracts the antenna gain from the EIRP, giving the conducted power limit.

Every old Ubiquiti radio handles this nicely. I suspect the PTP550 does too. But I don't have one to test.

The rules specify EIRP limits using tortured language. They say that when the gain of a PtMP antenna exceeds 6 dB, the power limit (+30 dBm conducted) is reduced by 1 dB for each additional dB of antenna gain. That also applies on U-NII-2, where the EIRP limit is +30 dBm. It does not apply to PtP radios on U-NII-1 or -3.

The conducted power limit (all chains) is +30 dBm on U-NII-1 and -3, the only bands currently certified (I assume DFS testing is underway for -2). The EIRP limit is +53 dBm ("if the antenna gain exceeds 23 dB") on -1 and unlimited on -3, but the effective EIRP is capped, per the rules, by the out of band emissions. Thus a super-clean PTP650 might be allowed +60 EIRP on U-NII-3, while (at the other extreme) a MikroTik LHG5 is allowed +25 dBm.

I raised the question of the actual allowed EIRP limit (which is based on out-of-band emissions, at least on U-NII-3) of the PTP550 several weeks ago, and never got a clear answer.  Does anyone in the US have a pair up and running with higher than +36 dBm EIRP?

Because if what you say is true, this radio is worthless in the US and I've got to go back to Mimosa. And I have about a hundred units to procure.

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Thanks point out. Actually our regulatory engineer also point out the errors.

Here is my regulatory engineer's comments:

Antenna gain and Type is limited by FCC Part 15 Rules and has nothing to do with the EIRP limitations of the FCC Rules. 

The PTP 550 Connectorized is not permitted for sale in the US as the PTP 550 does not support external antennas

When customer says that ‘Most PtP radio makers don't set a limit on the antenna’ this may be correct for licensed band products but for UNII the limitation on antenna gain and type is due to FCC rules for Part 15 transmitters, see attached KDB 353028, where only approved antenna types and antenna gains can be used. The PTP 550 grant approves 2dBi and 22dBi Flat Plate antennas, the user guide reflects a 23dBi integrated antenna.

When i checked Ubiquiti or Mimosa, their FCC approval has no big difference compare to ours. I am sure you can find more details by compare the FCC approval and test report under FCC web page.

@allenyu wrote:

The PTP 550 Connectorized is not permitted for sale in the US as the PTP 550 does not support external antennas

Uhhhh this is news to me... it is available in the US, PN C050055H001A... currently in stock and available from Winncom.

I have a PTP550 connectorized unit with 2ft Liard dishes (28dBm) on both ends of the link.  I stay within the FCC EIRP limits and if you put the antenna gain in the radio with coresponding country code (althought the FCC version of this radio does not ask for country code), then it complains if you try to go above the power limit. Correct me if I'm wrong but every ePMP based radio does this?

The PTP 550 FCC grant approves 22dBi Flat Plate antennas, which means the connectorized radio can work with a antenna with up to 22 dBi in my understanding.

AllenYu, Nathan is right. You can use whatever antenna you want. The type approval does specify which antennas are "approved", meaning tested with the device, but in practice a fixed U-NII radio that requires professional installation (that includes the PTP and ePMP families) can use a different antenna so long as its gain is properly characterized and the operator takes responsibility for staying within the limits. That's why there are so many antennas on the market. There are devices that require an integral antenna, and some where the FCC is somewhat picky, but you can be sure that the PTP connectorized radios get used with a wide range of antennas, legally, in the US.

You may need some help in the compliance department.

How well does the Laird work with the PTP550? Is it the HDDA5W-29-DP? How well do they mount together?

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BTW, to clarify, the FCC type approval does specify antennas, but a professional installer may substitute a lower-gain antenna, or another vendor's antenna that has the same or lower gain. So a proper type approval for a connectorized PtP radio would be run with, for instance, a 3 dB antenna (low end) and a 30 or 34 dB antenna, and possibly sample values in between. If you didn't test it with a high-gain antenna, your test lab or compliance guy who ordered up the test goofed. Unless the radio's performance is so poor that higher gain would have failed.

From the KDB you posted:

B. Question: Can antennas not listed in an equipment authorization approval for a part 15 transmitter be marketed and used without further approval?
Answer: Except as noted below, an antenna not listed in an equipment authorization that is the same type [Section 15.204(c)(4)] with equal or lower gain (same physical arrangement, generates the same in-band and out-of-band characteristics in all spatial directions) may be marketed and used with a part 15 transmitter.

1) Example permissible types of lower gain antennas—If a device was certified with a 26 dBi parabolic reflector (dish) type antenna, then other smaller parabolic reflector antennas are allowed without additional equipment authorization....

For PTP 550 connectorized, FCC grant includes flat panel antenna with gain of 2 dBi and 22 dBi. With that, it means that customer is ok to use PTP 550 connectorized with antenna gain between 2 and 22 dBi in FCC region.

And I'll reiterate: There are three reasons why you only tested with a 22 dB panel, which technically means we'd be noncompliant using a 30 dB dish. And didn't test to the edge of the band, just the Wi-Fi popular channels (which are all noisy).

1) If you didn't test it with a high-gain antenna, your test lab or compliance guy who ordered up the test goofed.

2) The radio's performance is so poor that higher gain would have failed OOBE or some other test. Maybe the early 802.11ac-Wave2 chip is just not very clean.

But I'll add another option here:

3) Or your product managers intentionally crippled the device, limiting its maximum EIRP and channel choice, in order to prevent it from cannibalizing sales of the PTP670. Which would be ridiculous, since they're in totally different markets and price tiers.

You've just handed this market back to Mimosa. Assuming case 1, Just by filing the FCC paperwork wrong. Assuming case 3, just by greed. Hey, I used to work for DEC, which 30 years ago was the world's second-largest computer company. But they didn't want to cannibalize their superminis with cheap desktop PCs. So others did instead and DEC became history.

Look at the PTP450i's approval for what it should look like. I may use that in a few places but since it's only 1x40 MHz it doesn't have the high capacity or dual-channel support that makes the 550 so attractive.