Howdy folks, Looking for some advice from people who probably have more experience with this. This site I'm at has 5 wireless serial radios (industrial wireless). They operate at 900MHZ. Each radio is configured to have a wireless channel that is offset from the rest. They are currently configured to use channels 1,4,7,10,13. Each is configured to be a Single to Many. IE each of the 5 transmitter talks to multiple receivers. 4 of the radios are working as well as you could probably expect. We see mostly clear communications, with the odd bit of noise. The last radio gets some communications through but mostly its noise. A couple of the receivers are slightly better but still pretty noisy. Below I'll provide a list of some of the things we have tried to resolve this. But for now our next step is to completely reprogram all the transmitters/receivers to be on a different channel and bring them on one at a time to see if we can't pinpoint where the trouble is occurring. Now to my main question. I've attached a picture of how the attenna's are arranged It seems odd to have the 3 "stacked" above one another. Is this going to cause problems? They don't know which antenna this radio is using. I tried swapping two of the antenna's, but didn't seem to make a difference. I'm thinking their issues boil down to line of sight issues. But thats just based on running out of other ideas :) If you have any other suggestions as to what we can do they would also be appreciated. Thanks, -Dave Things we have tried: -Verified that the serial communications is working from the reciever to the controllers. This appears to be working 100% -Changing the receiver for a new one -Changing the transmitter for a new one -Moving the antenna on one of the more troubled receivers -Swapping the antenna on the troubled radio for one that isn't having problems.