Not getting good results with Wilson amp and yagi

NathanP · EVDO User Joined: 02 Jan 2008 Posts: 38

I have a Wilson amp (801105) and a yagi antenna. The yagi is an 800mhz, and I'm on Alltel. I live 25 miles from the tower, and I can get EVDO . . . but the signal goes all over the place. I go from no signal to 3 bars in about 3 seconds, then back to no signal. I'm always able to get 1x, but the EVDO only works occasionally. That tower is the closest tower that offers EVDO. Alltel even lists my area as a fringe area. There are no other cell companies with towers out here.

Any suggestions are helpful.

By the way, I called Wilson about the problem and they just laughed at me for trying to get a tower 25 miles away. I live in Western Kansas, and it is pretty flat with almost nothing between me and the tower.

n6gn

Wilson can laugh, but from a point of signal strength, you actually do have a shot at it. You are probably in about the best situation, other than not being elevated with respect to the ground between you and the tower, to make a go of it.

What surprises me is that you can get things to work at all beyond 19 miles. If in fact you have limited connectivity at 25 miles, it says that the PILOT_INC setting on that system is higher than normal. I think that a value of 4 amounts to a delay limit between base and handset of about 19 miles maximum. The setting on the base you are trying to use must be higher.

So, if you really are within the system-set maximum cell size as it appears, I would suggest chucking the Yagi and putting up a grid reflector antenna, as high and stably as you can. This is almost certain to pick up more than 10 dB relative to the Yagi. If you can get it higher than the Yagi, I suspect you will pick up some more signal and perhaps, more importantly, more reliability.

On paths as long as yours, there are other problems that can and may occur. However, if you don't mind the $50 for the antenna and some experimenting, that's what I'd suggest you try.

n6gn

NathanP · EVDO User Joined: 02 Jan 2008 Posts: 38

I currently have the yagi 25' above ground. I could put the grid antenna at the same height, but would I just be wasting time?

Option #2 is to move the entire system 1.5 miles closer to the tower. That location is about 75' higher, plus I can use a tower that would get the antenna about 40' above that. In other words, I can move the entire system about 115' feet up and 1.5 miles closer to the tower. Should I just go straight to this option?

I'd like to get it to work at my current location, but if putting a grid antenna at the same height as my yagi won't do much good, I'll just change locations.

Also . . . can somebody recommend a good grid antenna, and where to get it? I currently have RG8 coax cable and connections on my amp. I'm not sure if that matter, just thought I'd mention it.

xrayman · Posted: Sat Feb 02, 2008 10:56 am Post subject:

NathanP,
You can find more info about the grid antenna tested by n6gn in this thread. http://www.evdoforums.com/viewtopic.php?t=5106
I recommend using low loss cable like LMR400 or LMR600. Get the cable with ready made and tested ends if you don't have experience making up cable with "N" connections. Using cheap antenna wire you will lose most of the signal gained by the antenna, with runs of much length. http://www.ocarc.ca/coax.htm

NathanP · EVDO User Joined: 02 Jan 2008 Posts: 38

Wouldn't I want an antenna that would support 800mhz? Such as:

http://www.hyperlinktech.com/web/900mhz_ism_grid_antenna_15dbi.php

Or would the one n6gn metioned in that thread still work for me?

ChefPeta · EVDO Fledgling Joined: 19 Jan 2008 Posts: 14

NathanP · EVDO User Joined: 02 Jan 2008 Posts: 38

n6gn · Posted: Sat Feb 02, 2008 12:38 pm Post subject:

Nighthawke70 · EVDO Heavy User Joined: 16 Aug 2007 Posts: 111

Nathan's going to have to go Industrial Duty on his kit. LMR400 with (preferably) a 2-3 foot diameter SOLID microwave dish set up for the 1-2 GHZ bands, not a do-all grid. For the amp, the Wilson unit might not be enough. He'll have to go the full 1 watt allowed by the FCC for 802.11a bands. That amp will run him a pretty penny.

(Hope y'all got time for a story)
I ran in the 802.11a band a 9 mile point to point rig to an island that only had dialup until we punched out there with a WAP. The mast we had at the office was a 75 foot cranky, 3 point guys and braced well. The end point was a 65 foot rat shak special. The upper lift was reinforced with an external sleeve and every hole on the collars on the mast had a guy wire attached to it. It looked like a scale model of a 1500 foot TV antenna with all those guy wires hanging off of it. It was overbuilt, overdone, but considering the hell mum nature put it through, it did well. It endured two major tropical storms, one a strong tropical depression that put a bend in the mast, but it stayed up and operable, even though the swaying of the assembly in the high winds made surfing the net a bit interesting. Had an F1 tornado come past it, blowing the roof off an adjacent townhouse, all it did to the mast was straighten the banana out of it and improve the reception. All I had to do was readjust the turnbuckles on the guys.

Both ends had 3 foot diameter microwave dishes on them tuned for the 802.11a bands, and ran 1/2 watt commercial amps with ORINOCO WAP managers up to then via LMR400 with commercial ends. The rig pegged out at >-1dB, >-5 to -10dB in weather.

25 miles... If he gets it operable, he MIGHT be breaking a record for distance run on the 802.XX bands on the suggested setup.

n6gn · Posted: Sat Feb 02, 2008 1:45 pm Post subject:

I don't think there's any support for the need for a solid dish. Even at PCS, where the grid spacing is most marginal, I measured the WiFi version to have very near theoretical maximum gain. It was slightly better ( in terms of theory) at PCS than at 2.4 GHz where it was designed.
I'm pretty certain that the loss due to not being solid is under .5 dB and maybe under .25 dB. I think a good trade off considering the difference in windage. Either will no doubt come apart in a hurricane but I think the grid has some advantages in terms of staying pointed with modest tower/support.

25 miles is nothing near the record for 802.11 DX. I've done that with small antennas myself and the real fanatics are well over 100 miles. I personally have made contacts at 10 GHz over 400 miles with 100 milliwatts that had enough S/N ratio (briefly) to support WiFi. Admittedly that was with tropospheric inversion propagation and between two 6000' mountains, but hey, it's possible!

n6gn

ChefPeta · EVDO Fledgling Joined: 19 Jan 2008 Posts: 14

jameswadewilson

I thought that our Verizon coverage around Marshall, NC was all 800 Mhz and it now has EVDO. Did they change the frequency to do EVDO? How would one know?

Wouldn't an antenna cut for 800 Mhz work just fine for 1900 Mnz since it's a multiple?

powrby4d · EVDO User Joined: 24 Dec 2007 Posts: 34

In the next month or so in search of the best EVDO Rev A signal I'm going to be doing a comparison of a bunch of Omnis (3dBi window, 5dBi magnet, 7dBi desktop, 9dBi trucker) as well as two yagis (10dBi, 19dBi) and the 24dBi WiFi grid antenna mentioned in this thread. (shameless plug - only some of this is from 3Gstore but as a side note I have purchased a bunch of stuff from 3Gstore and have been thrilled with all of the products and especially post-sales customer service).

I have a choice of 5 Sprint towers on an arc radius ranging from 7 to 16 miles over rolling hills with heavy woods, with the antenna pretty much just under the level of the highest land elevation intervening by about 20 ft.

Antenna elevation is unlikely to exceed 15 feet (attic or rooftop).

My question is two-fold regarding some of the configurations mentioned here:
1) Sounds from my general reading like there is a mix of connecting dual-band and single-band antennas to dual-band amplifiers as common practice. Some amp manufacturers say connecting a single-band to their dual-band amp will destroy the amp? Has this happened to anyone and is there a configuration that will allow the acceptable use of a single-band antenna (e.g. the 24dBi grid) with a dual-band amp? I was thinking a 850/1900 MHz diplexer might do it but at a cost to the 1900 MHz signal strength.

2) As you folks are hooking up these ultra high gain antennas, particularly amplified, when I do the math on the EIRP this seems like it would be easy to exceed the FCC EIRP limits - not just on the directional signal but on the side and vertical lobes. Has anyone had their brain cooked while standing 6 feet beneath their nifty grid/yagi setup taking RSSI readings, or else had any visits from the FCC?

Sorry if any of this is the ugly stuff no one likes to talk about.

powrby4d · EVDO User Joined: 24 Dec 2007 Posts: 34

oh, I forgot, I'll also be testing a 7dBi panel antenna as well. Hoping to learn a lot.

n6gn · Posted: Thu Jul 17, 2008 10:33 pm Post subject: