PEACE OF MIND.
Every 2.4GHz receiver, DSM-based or not, must deal with two technical problems common to all 2.4GHz signals—reflected signal fading and polarization blind spots at a long-range from the RC transmitter. If not adequately addressed, both issues could mean the end of a model. Only patented Spektrum™ MultiLink™ receiver technology provides you with the best way to deal with these technical issues.
ELIMINATES REFLECTED SIGNAL FADING
Reflected signal fading occurs when a 2.4GHz signal is canceled out at the receiver by its reflection bouncing off a conductive surface such as batteries, engines, and fuel tanks. If the signal reflection arrives at the receiver precisely 180 degrees out of phase from the original signal, the result is the same as a noise-canceling headset—silence. That's a real problem if you're only using one receiver.
With Spektrum MultiLink receivers, you have the protection of the primary RC receiver connected to one or more satellite receivers. By mounting the smaller satellite receivers away from the primary receiver in different orientations, the odds of all of them experiencing signal reflection simultaneously are reduced to a statistical impossibility. No single receiver can come close to providing that kind of protection.
ELIMINATES RECEIVER BLIND SPOTS
The farther a 2.4GHz receiver operates from its transmitter, the greater the chances of signal loss when its antenna is pointed directly at the transmitter. This is referred to as a polarization blind spot. By using multiple receivers with different antenna orientations, the dual path diversity of Spektrum MultiLink ensures that one or more will always be able to clearly "see" the signal.
An "antenna-less" receiver is a term coined for a receiver with an internal antenna. There is no whip or wire antenna. The antenna is essentially a tracer on the receiver's Printed Computer Board (PCB). These types of antennae are prevalent on GPS, WiFi, and cellular devices, because they are easy to design for tight spaces and are relatively more cost-effective than the alternative. Throughout our extensive lab and field testing, we have found these to be an excellent option for Radio Control receivers and, in many cases, perform better than "whip style" feeder antennas. It is important to note there are currently several remote receivers with "multilink" that feature this antenna-less design.
One of the most important aspects of PCB antennas is that they are omnidirectional. This means they have the same radiation pattern all around the antenna except for the Y plane. So, when installing these into an aircraft with the main receiver with 1 or 2 main whip style antennas, it is not critical that they are oriented in a specific direction.
A trade-off with a PCB antenna is that the device itself is effectively the antenna, so the placement of the receiver is key. The distance the antenna is from particular objects in your airframe is one of, if not the most critical, aspect to keep in mind. As with whip-style antennas, the antenna tip must be at least three inches (roughly eight centimeters) away from other antennas, batteries, fuel tanks, engines, and electronic devices such as ESCs, motors, servos, etc.
Another point to keep in mind, carbon fiber can block the signal from your receiver. This mainly pertains to sailplane and glider models with a completely carbon fiber laminated outer shell or fuselage. In these cases, it is not recommended to use these receivers.
As with any RC receiver antenna installation and setup, performing a range test before the flight is essential to confirm that all is working as it should. AND to keep an eye on your transmitter's flight log data to better evaluate the performance of your receiver(s) after each flight.
UMX SPEKTRUM RECEIVERS
Spektrum UMX receivers are designed exclusively for smaller RC aircraft such as park flyers and ultra-micro aircraft that use materials that create little signal reflection. Because they have little to no blind spots or signal fading, they do not feature Spektrum MultiLink. Also, these models are almost always flown close enough to their transmitters that the size and effect of any actual antenna blind spots are minimal.