What are good settings to use for Tx Power and Antenna Gain with dd-wrt on my router (WNDR3700v1)? Currently, it is set to the defaults of 20dbm for Tx power and 0dbi for antenna gain. I want to push the envelope without getting the FCC to come knocking at my door. Has anyone done this before?
I have experimented with many routers using DD-WRT setting up long distance wireless links, and honestly I have not noticed much gain raising the TX from the stock output to the limit of 251mw. I notice no difference over 70mw on a WRT-54G, a WHR-G300N, a DIR-825, a DIR-615, an E3000, and several others. Some of them I haven't noticed any difference at all raising the TX any amount. All of the routers I have listed I have tested over a distance of two miles using 19dbi gain yagi antennas on each end.
Just experiment a little bit, raise your TX and see what your signal strength is at distance. You will likely come to the same conclusion I did, there is no need to pump excessive wattage through your radios (which is also hard on your power adapters... I have replaced several) if your not going to see any increase in signal strength.
A bigger antenna will give you much more signal strength at distance than increased wattage will, and it will do so without taxing your radios and power supply.
I will also add that excessive wattage through your antennas that are not big enough can also create signal distortion, which can actually decrease perceived signal strength. To use a metaphor, imagine your antenna as a speaker and your router as your stereo receiver. If your speaker (antenna) is small your music (signal) will be distorted if your receiver (router) is set at full volume (TX).