Trying to increase Wimax signal strength in Japan... need help!

[Tengis]

I had another thread about a yagi antenna I built (I built two of them) but Im having trouble getting it to work as well as I expected so Im coming here for advice.

Basically, here is my situation. Im stationed in Japan (USAF) and the internet option we have on base is absolutely horrible AND insanely expensive. Advertised speeds are 20mbps while actual speeds are 1-2mbps with a data cap of 150gb... all for the lovely price of $120+ depending on which package you are forced into.

With two towers less then 1 mile from me I decided to roll with a wireless wimax option that has unlimited bandwidth. Best case scenario speeds are 50mbps down and 15mbps up. I get around 4-5mbps on average down and 1-2mbps up. The signal strength on the router is rated at 1-5 bars with no way to read the strength other then a x/5 fraction. I typically get 3/5.

The antennas are internal and very small. Here are some pictures of the internals and my yagi antennas:

I tried the antennas with and without baluns with similar results of 2/5 signal or the occasional 3/5 signal. Im connecting them with a 1.5 foot section of RG174. Ive got some u.fl connectors to RP-SMA to go from the router to a suitable connection to connect antennas.

I used this website as the guide for both of those antennas and used a different yagi calculator to figure out how to make the balun:
http://www.ab9il.net/wlan-projects/wifi6.html

Do you guys suggest I try a different antenna type? I was thinking maybe a double bi-quad antenna like seen here:
http://martybugs.net/wireless/biquad/double.cgi

Thoughts? Im just not sure what to do at this point. I have no other options for internet since I am stuck living on base and the physical internet they allow onto the base is slow and expensive with a low data cap.

 

[BigBadAl]

Hmm well, as I'm sure you know, that there is a 13 element yagi, the more elements the antenna has, the more gain it has, but also, the more directional it becomes.

It may well be that you are struggling to get the antenna pointed steadily in just the right direction for a sufficient period of time to get an accurate reading.

Of course I could be way off the mark as well.

Providing you followed all the instructions and you used the correct cable 50 ohm vs 75 ohm and there are no kinks or other damage and all your terminations are good, the only other thing I can think of is the orientation...

There's a thought.... have you considered polarization? Horizontal versus vertical? The tower you refer to may be vertically polarized in which case you'd need the yagi to be in the same orientation to get the best gain from it, vertical to horizontal may work over the mile or so you state, and it may well give the results you mention.

Just a thought ...

 

[Lost-Benji]

Hello, long time lurker and seen this and had a good chuckle.

I am a both a IT Tech as well as a Communications Tech so I think I am a little more than most to answer this. Should I mention I was one of a few here is Oz who rolled out WiMax?

Anyway, OP, you need to first find out what frequency their WiMax is running on and stop wasting time with dodgy Yagis. Yagi antennas work great but for lower frequencies. When your talking microwave, you need to step it up a few gears. Leave the homebrew for those who mix ambitions with capabilities and a good dose of placebo effect.

You will bee needing a phased-array or better known as a panel antenna designed for the band being used. Common bands are 1.8GHz, 3.6GHz, 5.8GHz or 6GHz. Yours however going by the details I found on the radio is 2.496~2.69 GHz,
http://registry.wimaxforum.org/certification/395
http://registry.wimaxforum.org/site...M2510P-F_Certification Certificate_Signed.pdf
This is on the top edge and just out of the WiFi band and you will find that most WiFi capable panel antennas will work as most phased arrays are fairly broad in bandwidth.
If on the prowl, you will be best with a MIMO panel and you will need to source RF adapters to suit the terminations on the radio. They do exist and will convert to SMA style allowing a WiFi antenna to work. You will need to confirm the site from which the WiMax is being transceived from. If you are unsure on the fittings, go find the avionics (You said you were USAF) guys and ask them to chase the leads for you.

 

[Tengis]

Ive broke open a few commercial antennas including a few yagis and found very shoddy construction ever since I started to look for a way to increase my signal strength. Also there are one or two people here with panel antennas but according to them their signal strength (or speeds) dont go up or down with the antenna connected. Hmmm.

PM sent...

 

[Lost-Benji]

Hey Tengis, if you have time and don't mind tinkering then by all means, go for it.
Some basics to keep in mind;

• WiMax is NOT always MIMO, some radios are single-radio and support antenna diversity I would be suss on your radio looking at the two different antennas and their mounting).
• Antenna/signal polarization IS important.
• Multi-pathing can see big issues in built up areas (Cities=Buildings=Reflections) although they are a derivative of OFDM, just not very tolerant as later designs.
• Transceiving devices are designed for 50ohm impedance's, not 75 or 300ohm.
• WiFi WILL interfere with the band used in your case (stupid band to use).
• Higher gain means more focused RF beam, not always best for MIMO but a good way to go if you CAN see the transmitter site.
  The Fresnel zone would be about 8-10 degrees either side of centre at the halfway point.

http://en.wikipedia.org/wiki/WiMAX

If you source a good quality MIMO panel antenna and get your aim and polarization correct, you WILL see gains. You need to keep cables short as possible, fitting count to a minimum and noise sources away from device and if possible, out of the Fresnel zone.

The biggest issue with two-way comms is not receiving enough RF, it is trying to get your much smaller signal back to the Transceiver.

 

[Tengis]

The antennas on my wimax router are diversity according to the documentation I've found. The problem with my quest for getting perfect signal is that I DON'T have line of sight to the tower. It is pretty damn close but I don't have a direct view from any of my windows or balcony... it's kind of around the corner of my building.

My main issue has been upload speed like you said. I've gotten router positioning and various antennas situated (including random wifi antennas I have laying around) to get good download speeds.

 

[Lost-Benji]

If you don't have LoS, then good chances that you are getting in-direct signals (reflections), maybe look at a couple of Omnis?