So…initial testing shows much poorer results than I was hoping for.
While the GMRS repeater running 8 watts with a 7dbi gain antenna has full coverage of the entire immediate area and being reachable 30 miles away.
The 1watt goTenna mesh is attached via 12m of LMR-400 (appox .3watt loss) to a 6dbi antenna mounted just below the GMRS repeater antenna. Looks like I’m putting out approximately 1.7watts ERP at the antenna.
My units failed to communicate with a gotenna approximately 3 miles away but with a slight hill in the way even though I am higher up. I am able to reach a gotenna at a higher altitude a little bit farther out.
I also lost contact with another gotenna that was driving around the base of the hill where the node is located.
This seems to indicate that the 900mhz is severely less tollerant of terrain than 460mhz.
What is the elevation of the repeater? 900mhz is definitely line of sight. 460 will also “leap” around buildings because the wave is a lot longer than the 900.
Based on the topo maps goTenna uses, looks like I was transmitting from about 853ft last night trying to communicate with someone around 590ft. There peak between us shows as 866ft.
cough Above sea level My repeater’s antenna is legally placed as far as the FCC needs to be cocerned with the anetnna no more than 20’ above the structure it is mounted on. =D (actually, I think thats 100% true)
@gua742 converted my unit to MOAN: The unit has an SMA antenna jack soldered on. I’m then converting from SMA to N-Type through a short jumper and then to the feedline.
I don’t think i would have tried that much feed line. Instead I would have ran power up to the Gotenna. Even LMR 400 is going to be pretty lossy with 900mhz at only 1 watt. It looks to me like all of your numbers come from calculations based on perfect conditions rather then actual measurements. Are we sure the Gotenna is expecting a 50 ohm antenna/feedline match? I have no reason to assume that since I have not went through all of the technical specs. If you don’t achieve a true 1:1 SWR you could be losing more power then you think. Even the moisture in the air is going to effect propagation in the 900mhz spectrum more then gmrs. I also wonder how the GMRS repeater might effect the Gotenna since 462.55*2mhz is 925.1mhz.
Did you disconnect the original Gotenna antenna?
Is TX any better then RX?
EDIT: One of my Elmers told me long ago that extra connections like you mention below look like a “lump” to the RF energy. That could also result in extra reflected RF losses. I really don’t know for sure but a balun in the system might help.
Range testing in my own neighborhood. I was able to get pretty reliable comms in a rural area with a stationary node at 1.5 miles. The area is rural. The node was mounted around 24 feet in the air. I had to hold the other Gotenna above my head a couple times at that distance.
Starting tonight and every Monday night in Northeast Los Angeles (Eagle Rock, Glassell Park, Mt. Washington, Atwater Village, Cypress Park, Highland Park, Montecito Heights, Sycamore Grove, Hermon, Monterey Hills, El Sereno, Rose Hill, Lincoln Heights), we’ll have two FRS radio net check-ins at 6:30pm and 7:00pm). During each FRS net we will be doing a goTenna mesh net using the emergency shout feature:
THIS IS A TEST OF THE EMERGENCY BROADCAST MESH NETWORK.
THIS IS ONLY A TEST.
Please respond back with your current neighborhood location and your FRS call sign and how many hops.
We currently have about 12 goTenna mesh units deployed throughout the area and one stationary relay node. We’ll use this weekly test to determine the extent of the mesh network we’re building and will constantly be looking for opportunities to place more relay nodes through out the community.
All community members are asked to keep their goTenna mesh units on and with their phones at all times and charge them when they charge their phones.
We’re also doing group buys to bring the individual cost down and get the units further deciminated throughout the area.
Solar panel I’m using is a Amazon sale special, supposedly 7 watts but I measure like .350 (which is enough for gotenna, it charges at very low power, great for solar).
Basically this one, it was about $20, the brands and actual measurements vary a lot at the low end of the price range.
My repeater’s antenna is legally placed as far as the FCC needs to be cocerned with the anetnna no more than 20’ above the structure it is mounted on. =D (actually, I think thats 100% true)