Advice on which antenna for a Clear Hub Express

[Jesse]

Hello,

Just got service from Clearwire using a Clear Hub Express. The service is good but I'd like to make it more solid and improve indoor signal strength so I'm looking at an outdoor antenna. My location between antennas leads me to ask which type of antenna would work best.

According to the Clear coverage website my house is close to two towers, one 500m away and the other 750m away. My house is also inline between both of these towers so signals from them are 180 degrees apart. I also have three other towers inhte area but over 1000m away.

I'd like an antenna that will take besst advantage of the two near towers, should I select a panel or omni directional antenna????

Thanks in advance for your help.

J

[thuor]

A directional panel antenna is almost always the preferred solution over an omni even in such a situation. Here's why:

1. Just because you are in between two towers doesn't necessarily mean that your location will receive equally strong signals from either tower. In fact, it most likely will not be the case otherwise this would be a very inefficient use of channel capacity by the carrier. I.e. the tower antennas will be oriented to cover different zones with minimal overlap so that the carrier may serve the largest number of subscribers.

2. In setting up your outdoor antenna you just want to orient to the direction of maximum received signal strength so even where you have two equally strong signal a more power antenna will work better than a lower gain omni antenna.

3. Omni antennas are best in situations where you have reflections and obstructions of the signal arriving from one tower - typical for a heavy multipath fading environment e.g. many building obstructing the signal or causing it to bounce around. So when you can't really find a dominant direction where signal is strongest the omni helps pick up the signal from all directions.

4. Often a nice solution in environments in between these two extremes (i.e. don't have a clear line-of-sight and don't have multiple reflections) is to have a primary directional antenna and an auxiliary omnidirectional antenna - that way you get the benefit of MIMO spatial diversity to improve performance.

Here is a kit that includes the 4G Panel/Omni outdoor antennas: http://www.rfwel.com/shop/4G-USB-Mod...tenna-Kit.html

[udaman]

similar situation. I currently have a Clear "home wifi" modem (Gemtek I suppose?) which looks almost identical to the 'hub express' model being currently offered by Clear, except exterior color of case and on the HE there is one external antenna port, additional ethernet? So am considering returning the HWF to Clear and getting a HE to add an external antenna to.

Inside home (can post up a screenshot of the Clear coverage map for my area if it might help), no matter what widow sill the HWF is placed next to, I could only get 1-2 led signal strength, and very slow, slower than DSL d/l & u/l speeds. 0.7mi from 3 towers equally spaced 120º apart from each other, 5 others just over 1+mi away.

Took the HWF modem & 50ft extension cord, up on the roof of the home, got 3 led in most orientations, with 4 led in single orientation at one end of home.

1. Should a HE & 16dbi yagi, be all I need to get pretty strong signal reception? There are two old UHF/VHF antenna being used to receive OTA digital TV from where I could mount an WiMax antenna 1/2 way (about 4ft to mid-point) up the mast.

no actual LOS to any towers, some trees, another down a hill in one direction, 4 led signal is from where the signal must go over the 405 freeway, from a location that is in the center of the 405 & 10 freeway interchange(assuming Clear's tower location map is correct)!

NO way to know how much a factor reflection fading is a problem.

2. Why is a directional panel of similar dbi capability preferred to the less expensive yagi directional?

3. Don't really want to spend the $$$ on dual antenna, and there is only one antenna port outside the HE (so would have to add another coax connector + pigtail to get 2 antenna capability). Not even sure what flavor of MIMO Clear is using in my area, anyway to find out?

[thuor]

Inside home (can post up a screenshot of the Clear coverage map for my area if it might help)

No this does not help. Coverage maps are very crude/coarse and don't accurately depict what localized coverage would be.

I could only get 1-2 led signal strength, and very slow, slower than DSL d/l & u/l speeds. 0.7mi from 3 towers equally spaced 120º apart from each other, 5 others just over 1+mi away.

suggests that perhaps you don't have a signal strength or interference noise power problem. LED RSSI (received signal strength indicator) is probably not the best way to figure out what the best window sill is because the LED just gives coarse readings. A better approach would be to compare the numerical RSSI and CINR values remembering that dBm (for RSSI) and dB (for CINR) are logarithmic scales - so 3dB difference in reading represents 50% difference in power!

1. Should a HE & 16dbi yagi, be all I need to get pretty strong signal reception? There are two old UHF/VHF antenna being used to receive OTA digital TV from where I could mount an WiMax antenna 1/2 way (about 4ft to mid-point) up the mast.

Recommend the 18dBi panel antenna (the default in this kit)which seems to work very well for most people. The VSWR of the 16dBi antenna can be erratic for some antennas which would affect performance for people with very weak outdoor signals.

no actual LOS to any towers, some trees, another down a hill in one direction, 4 led signal is from where the signal must go over the 405 freeway, from a location that is in the center of the 405 & 10 freeway interchange(assuming Clear's tower location map is correct)!

LOS is typically not required for 4G WiMax. In fact it is arguable that LOS is not preferred because MIMO uses channel decorrelation and spatial diversity to improve performance and a LOS channel would lead to very correlated channels for the multiple antennas.

Tower location as designated in map may also be deceptive as explained in this post: http://www.rfwel.com/forums/showthre...=2138#post2138.

The surest way to determine the optimal orientation is by trial-and-error antenna sweep (while looking at RSSI/CINR readings) - note that future adjustment may be necessary if/when they change the base-station antenna tilt/orientation/beamwidth or if the channel changes (have seen this for seasonal changes of as more users are added in a geographic area).

NO way to know how much a factor reflection fading is a problem.

Yes and not concerned with this because as explained above MIMO multi-antenna systems are designed with multipath propagation in mind. Some reflections are actually good!

2. Why is a directional panel of similar dbi capability preferred to the less expensive yagi directional?

Good question. Part has to do with quality control of the Yagi as explained above especially VSWR (which affects how much power is reflected) but the simple answer is just our experience - the panel just seems to work better and nothing in the specifications themselves can point to why. You are of course welcome to try the 16dBi - we have a 30-day refund period with no restocking fee so you would only be out the return shipping if you wanted to experiment on your own.

3. Don't really want to spend the $$$ on dual antenna, and there is only one antenna port outside the HE (so would have to add another coax connector + pigtail to get 2 antenna capability). Not even sure what flavor of MIMO Clear is using in my area, anyway to find out?

In our experience No. When you have a decent oudoor signal as you do, then adding a second antenna only gives marginal to no benefit - especially where you do have some useable, albeit weak, indoor signal such that you still have the Auxiliary antenna (internal to the modem) still picking up a signal.

If you do decide to add a secondary outdoor antenna then yes, you will need another cable, pigtail, lightning protection etc.

WiMax Wave2 certified devices required to support 2x2 MiMO Matrix A and Matrix B. Matrix A uses STBC (Space Time Block Codes) and Matrix B uses Spatial Multiplexing. Beamforming (AAS) is optional and hasn't been deployed. Regardless of what flavor is used, the antenna considerations are the same - provide enough antenna isolation to obtain spatial redundancy.