MikroTik

Hej,
i try to find information about the used anetennas in the hAPax3 / hAPac3 series for tweaking my wifi coverage. With "try and error" i was able to improve the coverage att same areas, but it is odd doing this without any information.

More specific:
- are the to antennas simular and both broadcasting 2,4 GHZ and 5 GHZ or is their one antenna per band?
- where do they have the strongest signal? Is the broadcasting just round or are their areas with stronger broadcasting power?

- is it possible to use an antennakabel for placing the antennas not exactly their i have my router?
- can i use other antennas? How can i find out if they are compatible with my router?

- is it possible to place the router i one room with one annettenna connected the normal way and just set the other antenna with an extenstion cable att the other side of a wall that desturbes wifi connection? (i have already a cabelcanal their).

if their is any how-to i wasn´t abel to find it. So please post just a link. I can read german, swedish and english.

i have had contac with an Mikrotik salesman and got these informations:

- the anntennas have no carateristic, they are just round.
- the anntennas are connected to the same bord, its just one devices with to outputs. You can not use each output seperatly.
- it is possible to use antenna extention cables.
- if you want to use an other extern antenna you have to choose one with to inputs.

But still no link to a teknical spec or a how-to...

I'm not an expert on WiFi, but I learned a lot while researching directional external antenna for a Mikrotik Groove52ac.

1) Regular dipole antennae like on the ax3/ac3 are omnidirectional like a donut ("round" in the XY plane but not spherical in X, Y, and Z axes).
2) The higher the gain of the antenna, usually the narrower the angle it covers. For a dipole antenna, the angle in question would be vertical, as in how tall the donut is along the Z axis.
3) For a two-antenna system (2x2 MIMO), it's generally best to have the two antenna together at an optimal distance from each other, since they work on wave interference when arranged in parallel polarization*. In other words, you cannot think of them as two separate antennae. You're thinking you can simply move one antenna on the other side of the wall, but that will not work. You have to treat them like a partnered pair of antenna.
4) The stock antenna are dual-band 2.4GHz and 5GHz. Inside, each antenna might actually be two separate dipole antennae connected to one RP-SMA connector, but I don't know this. Most likely it is one dipole antenna tuned for dual-band capability.



So, to answer your overall intention: you probably cannot get much better coverage by moving or changing the antennae. At best, you could experiment with the distance between the two parallel antennae (both arranged with their center axis pointing up at the sky), but the distances we are talking about are small (under 40cm). The easiest thing to do is mess with the transmit power (if you have the international version) and choose a band that allows you to increase the transmit power. There are several discussion threads on this forum about how some people set their hAP ax3 to Taiwan regulatory domain and then chose a specific 5GHz band and were able to get much higher power measurements. This may be illegal in your regulatory domain.


* Note that some 2x2 MIMO antennae are designed to operate perpendicular to one another, i.e. one is vertically polarized and the other is horizontally polarized. The hAP ac3 and ax3 appear to be designed for parallel antennae. I am not sure if they can handle perpendicular, though this is exactly the situation I want to use the hAP ax3 for--with an Alfa APA-L2458M912 directional dual-band outdoor panel antenna.

* Note that some 2x2 MIMO antennae are designed to operate perpendicular to one another, i.e. one is vertically polarized and the other is horizontally polarized. The hAP ac3 and ax3 appear to be designed for parallel antennae. I am not sure if they can handle perpendicular, though this is exactly the situation I want to use the hAP ax3 for--with an Alfa APA-L2458M912 directional dual-band outdoor panel antenna.

Every dipole is polarized in direction along the stick. So if you turn both antennae in vertical direction, you get 2x2 MIMO with vertical polarization. More complex antenna systems (like antenna array) will have engineered polarization direction, so it's possible to have dual-polarized antenna system or something similar.

When talking about MIMO there's only one goal: have paths between one Tx antenna and one Rx antenna as much separated as possible from path between second Tx antenna and second Rx antenna. Ideal arrangement is if both Tx and Rx side use dual-polarized antennae as polarization (90° angle) separates both paths ideally. But in ideal case Tx and Rx polarization planes should be aligned precisely. There's a slight problem with polarization: it gets rotated when signal reflects, so the ideal placement only works ideally when there's clear line of sight between Tx and Rx pair of antennae. Inside typical hoes, with many walls reflecting signal, the polarization plane turns wildly, bounced signals not only interferes with "main" signal amplitude-wise, it also mixes both MIMO legs. Receivers are designed to cope with that (some are better, some are worse), but things become non-ideal.
Second possibility to separate paths of both MIMO legs is to have spatial separation ... which means to have Tx antennae placed at some distance between them (multiple wave lengths, at 2.4GHz that's multiple of 12.5cm / 5in ... where most APs fail miserably as they are not large enough; at 5.5GHz wavelengths are proportionally shorter, around 5.5cm/2.1in, so having spatial separation of at least one wavelength is easier to obtain). And on Rx side as well (where most modern WiFi stations, read smart phones, fail as well, only a few laptops with strategically placed antennae get it right). This way signals from both MIMO legs are always interfering each other, but again receivers are supposed to deal with it. Larger spatial separation of antennae (both on Tx and Rx side) helps a lot, so using antenna jumper cables to create larger spatial separation might be beneficial despite jumper cables attenuation (so this works best in case where signal strength is good and additional signal loss of a couple of dB doesn't cause too much of degradation). But since receivers are not capable of performing miracles, 2x2MIMO speed gain will almost never be 2-times.

The mix of both MIMO techniques works somehow as well, i.e. have two antennae separated as much as possible and have them turned at angle (+-45° works fine most of times).
The gotcha with turning dipole antennae away from vertical direction is, as @dchang0 mentioned, doughnut-shaped antenna gain pattern. So this really works fine in one direction (if antennae are tilted by 45° from vertical direction, then optimum direction is in horizontal direction, perpendicular to antenna plane - when one sees antennae as if they were parallel, not one behind the other).

So yes, maximizing performance of a NxM MIMO (most of times that's 2x2 MIMO) is a bit of a magic and one might be able to get things working really good in certain direction but not elsewhere.

But are specifically the ac3/ax3 antennas actually a MIMO setup?

Or more simply the 2.4 GHz radio is connected to one antenna and the 5 Ghz radio is connected to the other?

But are specifically the ac3/ax3 antennas actually a MIMO setup?

Or more simply the 2.4 GHz radio is connected to one antenna and the 5 Ghz radio is connected to the other?

They are MIMO antennae.

But still no link to a teknical spec or a how-to...

For technical specs ... see ... viewtopic.php?t=203076&#p1049189