Bright House Networks - Legacy → [Internet] A question for BHNtechXpert re: WiFi hotspot antenna polarity

Hey BHNtechXpert,

I hope you can answer this question. Are BHN's free WiFi hotspots setup with antennas in vertical or horizontal polarity (or both)?

Also, are the AP's usually mounted on utility poles, or on business customer buildings?

Thanks,
Brian

1) No clue as it is not a topic I deal with every day

2) Both

From what I've seen, they are using circularly polarized antennas that are part of the equipment housing.

We have one at my business. The AP has a raised ring over the whole top that I would suspect is the antenna. It is mounted onto a wall, so the ring is vertical for the plane. We get pretty good reach with it, about 100-150ft from the building outside. And this is an all steel structure that blocks all GPS, halfs the cell signal in a very good reception area.

The phone line mounted ones are gray boxes, with 2 external pole antenna. Couldn't give you much on them other than our area is saturated to the point that I can stay connected via it while driving 5 miles to work through town.

What makes you think they are circularly polarized?

Are the antennas oriented vertically (straight up/down), or horizontally (parallel to the ground)?

vertically

I drove around on my lunch break, and I found a few AP's hanging on the cable TV lines. They are BelAir AP's, and the antennas are not mounted externally... so I can't see if they are horizontal or vertical.

I would guess that BHN would mount them vertical since that's the "standard" way to do it because laptop antennas are vertical... but smartphone and tablet antennas are only vertical when you hold the device in "portrait" orientation.

I found a tear-down of the BelAir 100SNE AP, which the ones in my neighborhood appear to be. It is here:
»electronics360.globalspe ··· teardown

It doesn't show the antennas, but the antenna connectors are definitely on the bottom side of the board, so I would assume that they are inside the enclosure, pointing straight down.

Vertical it is...

Are you saying that just because of my assumption, or did you get confirmation from someone?

No not from your assumption.

Great! Thanks for confirming it for me. I appreciate it a lot. You make the BHN customer experience for geeks like me much better and I really appreciate that you are available and respond so quickly.

Tell your boss that you deserve a raise.

LOL but I do have to ask why the question? You have more than one of us curious

+1 LOL

Well, there's a spot where I want to be able to use your WiFi that is just out of range, so I'm thinking of making a grid antenna to see if I can pull in the signal reliably.

I was honestly hoping that it was horizontally polarized, because that would help exclude other AP's in the area which are on the same channel as the BHN AP.

However, I understand that vertical is the normal way to do it.

I know that I can request for BHN to install hot spots in new locations, but I don't think there would be enough requests for this particular location.

You might be surprised and you should definately make the request

I'll consider it. But this particular location isn't a place that is a popular spot for people to congregate. As you know, I sometimes work from "home" and the BHN hot spots are really nice for me. In some places, I get 30Mbps download speeds... and that's fantastic compared to what I normally get on 4G from my cellular provider.

I have a "home" office at one of the Melbourne beaches too!

Specs I've seen on the antennas...

I see that you understand very well.

... and I'm guessing our "offices" are in the same general area! LOL

Yes, go on....

Used to work for an antenna manufacturer. I recognized the particular antennas I saw. Pretty much all antennas now used at 1.8 GHz and above are circularly/dual polarized. Since polarization is indeterminate after the first "bounce" the signal makes, it is a cheap way to improve coverage reliability. The individual elements are stacked vertically to provide omnidirectional (or 180-degree, depending on the antenna configuration) gain (or forming of the beam to focus the power sending more out towards the horizon (or next intersection!) and less towards birds and airplanes.

Actually, in regards to specs... the following document has more information about the BelAir 100NE series AP than I've found elsewhere. It's on a Russian website, but it's in English and I haven't detected anything malicious in it (I don't trust Russian websites). Here it is:
»winncom.ru/wp/wp-content ··· 0_NE.pdf

It appears that the standard antenna is an omni-directional dipole with 4.4dBi gain (which would indicate a small dipole antenna), and the transmit/receive sections of the device are pretty good. At 2.4GHz, which is what I'd be interested in for a simple grid antenna (a 5GHz grid antenna would be much more complicated). The AP transmits at 27.7 dBm (588mW) for 802.11g, and in a range from 26.5-27.7 dBm (446-588mW) for 802.11n.

The receive sensitivity is equally impressive. It lists -96 to -81dBm (0.251pW-7.94pW) for 802.11g and -96 to -76dBm (0.251pW - 2.51pW) for 802.11n; with the lowest power of -96dBm being for the lowest data throughput.

The worst reception of -96dBm would be too slow for me (6Mbps for 802.11g, and 6.5Mbps for 802.11n). So, if I can get at least -95dBm (g) or -93dBm (n), I'll be a happy camper.

I've read that a typical "WokFi" antenna gets at least 10dBi gain, so I think I can do this! A grid antenna should perform better than a WokFi, especially if the polarization and shape of the reflector are correct (which should help eliminate some multi-path distortion/propagation).

By my calculations, the AP is 230 meters away from my desired location. There aren't many obstructions between... mostly some trees (which will cause diffraction of the signal). I'm hoping that the polarization selectivity of the grid antenna will help me get the results I desire. At such a short distance, tropospheric reflection probably won't help me... but it might be slightly beneficial to aim the antenna upwards by a degree or two.

Yes, I'm really a geek.

EDIT: I changed nW to pW so that most people can understand the relative difference between the low and high values. I also ordered dBm from low to high (e.g. -100dBm is less than -90dBm).

Yes, I completely understand what you are talking about. The reflection/diffraction of signals in the microwave range can cause all kinds of crazy stuff to happen.

Dipole antennas, which are shipped with most consumer-grade AP's, and is what I believe to be used in these BelAir AP's, focus most of their energy in the same polarization as the orientation of the antenna. Generally, the higher the "gain" of a dipole antenna, the more signal is focused in that direction.

Obviously, due to the nature of signals in the microwave range, they bounce off of nearly everything and change direction as a result.

In my particular situation, there will be nearly line-of-sight to the AP. In fact, there will be only 2 or 3 (mature) trees in the way. So, if the AP has a dipole antenna with a 4.4dBi gain as I suspect, the signal received should be mostly polarized the same direction as the orientation of the antenna.

I'm going to try it this weekend. The experiment will be done with a wireless adapter which has a transmit power of 18dBm (63mW) and a sensitivity of (guess-timated) -68dBm to -90dBm, with an acceptable minimum (also guess-timated) of -85dBm.

Obviously, the cable type and length between the client device and the antenna will affect the overall effectiveness/performance. I'm going to use LMR-400 (flex) cable to start. At 2.4GHz, it has performance characteristics which should render it nearly transparent at the length required.

I THINK (capitalization is intentional) that my antenna should have a gain near 21dBi accounting for loss in the cable. So, I should be able to achieve reception (at both ends) at least in the range of -79 to -82dBm.

The unknown for me (mostly because this is my first deep venture into the world of wireless networking) is the ACK timing of the BHN WiFi AP's. As you should know, radio waves travel at the speed of light. So, the 230 meters we are talking about should only account for 767 microseconds (0.767 milliseconds). But, the timing of the silicon devices involved is much higher. So, if the ACK timing of the BHN WiFi hotspots is too high... the distance could definitely cause a problem.

I would think that the ACK timing would never be set lower than 200-800mS... but one never knows. So, it would be really nice to get a definitive answer from BHN.

These are easy to build and work very well on a device (router, AP, USB adapter) that has a single antenna.

»www.freeantennas.com/pro ··· s/Ez-10/

Yeah, that's pretty... but the antenna I plan to build looks even better. See the picture.

In other words, I plan to blow your specs out of the water.

Oooooh my antenna is bigger than yours....I love a good antenna fight!