Legal wifi propagation? (max 20dB)

I have set up a bridge from a SMC hotspot with 17 dBm output power.
Cable and other losses are -3.35 dB and the uinit is transmitting via an omni directional antenna with 6 dBi gain.
The repeater is located 1.1 km which gives a free space loss of -106.421 dB.
I am using a Buffalo Air Station Tubo G modell WHR-HP-G54 set up as a bridge.
This unit picks up the signal via a 24 dBi grid antenna which is connected to the bridge via a 2-way splitter. To the splitter is a second omni directional antenna with 6 dB gain connected to redistribute the signal in the local surroundings.
The receiver sensitivity of the Buffalo is -83 dB.
The nominal output power from the Buffalo is 16dBm for 802.11g that I am using.
When I enter these data in the calculation sheet I get a remaining margin for the link of 15 dB and the comment that the link should work properly, which it does and that the System is legal.

What I am looking for is a confirmation that the system really is legal using the bridge connection.

Can anyone help me with the confirmation?

Thanks in advance

Bjorn

to 100% guarantee that you are infact under the legal requirement that you mention, you are probably going to have to get it tested by an independent testing authority of some sort... short of that, do your best, to me it sounds like you are sitting ever so slightly under the legal limit.

Myself, I have been well over the limit in the past(26db router and 24db antenna), with no-one in a black helicopter telling me to shut it off, however I now go a bit under the legal requirements.

A good way to find out, is put a watt meter after any splitters and amplifiers and before the antenna. Take this real power reading and then calculate the antenna's gain on top. You're in Invercargill aren't you? I know a few people with watt meters down there who work for the big boy broadcast installations.

Dave, you've struck it lucky. Radio Specturm Management field testing officers always keep tabs on transmissions and their strengths. Even in rural towns they make 2-3 monthly visits and keep tabs on things.

I've had them knock on my door for 300mW once and they didn't know me or where I lived from a bar of soap. They don't need a black helicopter, just the MED company car, laptop and a few connected receivers. Triangulating a signal is to hard a work, it's just as easy to disconnect and antenna as you get closer to the source until you see the antenna on the roof then go knock on the door and deliver general user radio licenses to those who don't have one, or fine those not following the rules.

I've seen the odd second hand bird watt meter go on trademe, some have the 2.4ghz inserts with them, keep an eye out, they are very valuable for rf work.

Your buffalo is 40mW out. Your splitter probably throws in a 1-2dB loss so about 25-30mW then split, with 3dB down on each output, then output in to a 24dB gain antenna giving you an e.i.r.p somewhere near 3300mW before cable loss.

Take some cable loss in to account, you're probably around 3000mW (1000mW below the legal limit).

If you include the 6dB antenna on the same splitter, however, it makes no real difference since it'll only be about 40-50mW output.

The grand total e.i.r.p will still be shy of 4000mW. But without a watt meter to confirm what each antenna is getting, you won't know. No computer model can give you the perfect answer but it does sound like you under not over.

Gavin.