Ubiquiti 60 Ghz 12KM

The AF60LR is a 60GHz radio designed for long distance links. It uses the same dish reflector as the AF60 / GBE-LR but has different electronics. Thanks to this, working range increase 5 times comparing to the AF60 model. The author has installed a pair of AF60-LR devices on the distance of 12.5 km, between two urban locations. In both locations have very heavy 5GHz noise. Below is a photo of one side, right next to the AF24HD mounted on the same path:

The big difference between the AF60 and more powerful brother LR is the LR does not have a built-in 5 GHz spare radio, it is useless at that distance and only increases energy consumption. LR uses a maximum 30 W, 48 V power supply is included, not a 24 V power supply like the AF60. Can work in 58.32 - 69.12 GHz frequency in 11 channels, the channel width can be 2160 or 1080 MHz. It provides almost Full Duplex performance, although in fact the radio works in Half Duplex, it is such a fast connection that the performance is comparable to the full duplex. The manufacturer assumes the possibility of creating a connection up to 15 km with 1760 Mb capacity in full channel or 876 Mb in half. Bandwidth is limited to 1 Gb by Ethernet port used.

The configuration panel is identical to the AF60, it shows all important information about the device on one page. We see the signal levels at both ends of the link, along with real-time capacity and throughput, and modulation levels on each side.

If you are not familiar with millimeter wide radio waves then you need to know that the link distance in 60 GHz is limited by oxygen molecules in the air. They absorb radio waves significantly at 60 GHz. They take an additional 16 dBm for each kilometer, in addition to the basic loss of Free Space Loss. This means that long distance links must use channels that are as far away as possible from 60 GHz. Radio bridges at this frequency were usually limited to distances of less than 3 km. This is both good and bad - it limits the usable distance, but also removes most interference from other users. Their signals dissapear before they reach your radio. Also, the very short wavelength (which is the reason why it is called "millimeter wave") makes the signal beam very narrow, the given size of the dish gives a very high signal gain, of the order of ½ degree for AF60 / AF60LR.

The AF60LR overcome the distance limitation by using several methods, including higher Tx power, allowing the connection distance to be 5 times longer than the AF60. We must bear in mind that the rain will affect the connection on all frequencies above 11 GHz. Fortunately, this is not the H2O absorption peak, which is highest at 24 GHz. Heavy rain will worsen the signal or even disconnect the radio bridge, it is recommended to use a backup link at a lower frequency. None of us can afford to take breaks in the rain.

Speedtest (in graph) and one-way test result (in small window)

Speedtest (in graph) and one-way test result (in small window)

In full-width mode, radios can pass over 1 Gb even at this distance. The screenshot above shows the link and the two different speed tests (in the graph) and the result of the one-way test (in the small window). This connection is much faster than on the AF24HD radios we have on the same path, they usually run at speeds up to 774Mb but Full Duplex. Luckily we rarely need this amount of bandwidth on this link, but it's always good to be able to use more speed.

Speedtest duplex, download only

Above, the same test (duplex and download only) at half the channel width - has more stability and still gives us better bandwidth than they need. A narrower channel makes the link more reliable. The link with the AF24HD still works in parallel. Changing to a lower frequency channel starts to negatively affect the connection, especially from 66.96 GHz downwards. When running a link over this distance, we recommend using the top channels and it should be OK. The shorter distance, the lower channels you can use, this should be planned according to your needs.

Tools used for aligning

The hardest part of setting up this link is aligning. With such a narrow beamwidth, you can't just plug device to power, position it by eye and hope it works. It's a good idea to visually align them at the beginning. With the "Carpenter's Square" method (thanks to ClaudeSS, one of the Ubiquiti forum users), they managed to set them up quite well (together with AF24 and AF11FX). In order to improve the quality of the connection, the author created an optical system using a telescope, which brought very good results. The precise mount included in the set helps a lot in visualization. Once removed from the box, it is perpendicular to the front edges of the dish, rarely requires any alignment corrections, and attempting to correct the tilt can often result in signal degradation.

Telescope Orion Right Angle 6x30

Here is a close-up of the telescope itself - the Orion Right Angle 6x30. A mount has been built for it that allows the installation of a steel bar that clamps across the front of the dish (or other antenna with a diameter less than 90 cm). This makes it very easy to see where the antenna is pointing from the side and makes the visibility easy as long as you can see the other side.

Reference

The first six photos and the content of the post are not our, they are from the Ubiquiti forum.
Source

The graph below shows the attenuation of radio waves absorbed by oxygen molecules in the frequency range from 50 to 70 GHz

Absorption of radio waves by oxygen molecules

Absorption of radio waves by oxygen molecules

The frequency occupation in the world