Placement of model yacht antenna for optimum performance

Richard Ellis

Installation of antennas in model yachts can easily be done wrong. I have found most of these ways myself. The objective is to maximize the reception of signal from the transmitter. Even though the wrong way may work under good conditions the reception may weaken as the receiver ages or the battery voltage drops or there is interference or a little wetness gets into the hull.

First thing to do when you install an antenna in a boat is to record the length of the antenna wire as it comes with the receiver. Write that length on the radio paperwork or write it on a label and attach it to the receiver. Next, cut the antenna wire about three inches from the receiver. Strip and tin the wire ends then crimp on spade connectors to the stub wire and the remaining antenna wire. This will allow you to remove the receiver for cleaning and service by pulling apart the spade connection. When you get a backup receiver you will be able to switch receivers without fooling around with antenna wires.

1.   FULLY UNDER THE DECK – Placing the antenna totally under the deck can bedone successfully, but it is the most likely Installation to have weaker reception. The routing that works the best is to attach the wire to the underside of the deck along the centerline. See the blue routing in the drawing. The wire should come back along the centerline to just in front of the hatch, then it should make a circle around the hatch and then down along the side of the hull to the receiver.  Plan to make the antenna routing long enough so that the wire does not have to be crumpled up near the receiver. Do not route the antenna along the hull sides. When the boat heels from the wind the antenna wire may be below the waterline, which will cutoff reception.

2.  UP ALONG THE MAST – The green routing shows the mast side installation. The vertical antenna wire generally provides the best alignment with the transmitter antenna; that is, reception is best when the two antennas are aligned in parallel. This installation should not be used for metal or carbon fiber masts, which will shield the wire as it lies up along the mast. As the wire comes though the deck near the base of the mast bring it back and around the hatch opening. The wire can be attached to the underside of the deck with hot glue or package shipping tape, for example.  

3. VERTICAL AT THE STERN – Two versions of the stern antenna can be considered:

 A. Probably the best reception configuration of all installations has the antenna wire routed back from the centrally located receiver along the underside of the aft deck and then it exits through a hole in the deck and up the backstay. This installation keeps the antenna away from the main servos, which generate electrical noise. It is also makes the antenna length issue simple. Just run the antenna back then up the backstay as far as needed to make the required length.

   The simplest way to attach the antenna end to the backstay is to install an alligator clip at the end of the antenna wire. Make sure that the alligator clip is not electrically connected to the antenna by crimping the insulated wire. Alternatively one can use a hook and an elastic loop to hold the wire to the backstay.

B. Another good aft installation is the use of a model car flex tube antenna on the aft deck. The flex tubes available at most hobby shops are about a foot long. I would use this length. See the red wire routing shown on the diagram. If the antenna wire is too long to go directly from the receiver and up the side hull, then one could make the wire follow along the undersides of the aft deck in a large zigzag pattern. The objective is to make an antenna that has some straight segments pointing in multiple directions. For example, a horizontal antenna running straight along the hull centerline will have very weak reception if the boat is pointing at the transmitter. The reason that a primarily vertical antenna works well is that it receives well from all horizontal directions and generally is aligned with the transmitter antenna, which hopefully is held in a generally vertical position.

Loss of radio control signal is not always easy to recognize; sometimes a skipper will just think that waves or other boats pushed around the boat. Take the time to think about the antenna installation before the boat is together and it is difficult to fix.