1UGLYPUG

In 1978, I was an AF airborne radio instructor, and then a satellite communications instructor. We had some of the first "frequency hopping" equipment installed on our nuclear carrying aircraft. These were like the Futaba FASST frequency hopping systems. What a pain it was teaching digital stream signal technology to some of the older analog radio guys. If Futaba had decent customer service, I would recommend them hands down, but, their customer service stinks. 2.4 Ghz frequencies, or microwave, can be blocked by metal objects and results in loss of signal lock due to poor antenna installations. They also work best in line of site instances. That is why almost anything can block the signal, including the batteries in your plane, the metal push rods, and even servo wires. Extra receivers/antennas can only help, which is why I like the satellite receivers Spektrum uses. There are too many things that affect signal loss to even start here. On the comment about signals conforming to the "curvature" of the earth, HF frequencies , or those around the CB band, don't conform to the curvature of the earth, they bounce off the ionosphere,, to travel around the earth. All frequencies are "line of sight", or radiate in a straight line, in all directions. Unless you are using a dish antenna or beam antenna, the signals will all "spray" or radiate in all directions. The high or low frequency does not affect the radiation pattern, but the antenna does. The tip of the antenna radiates the less signal strength. I see lots of people with their transmitter antennas pointing the tip of the antenna at the plane, which is the worst antenna orientation possible. So many people don't know the radiation patterns of antennas, and don't realize the loss of signal it can cause. And don't touch the antenna which can severely reduce the signal. Some study of antenna radiation patterns and antenna signal reception, would help a lot of folks on here. Just a thought on the speed of linking when turning on the Futaba and the Spektrum. The Futaba does not have the model select data bit stream being sent out to guarantee you only link to your one model, whereas the Spektrum has the extra data bit stream being sent out, and guaranteeing connection to the right model. A plus for me, as I don't have to worry about linking to the wrong model.