RX wire 'Aerials'

[Basil]

Is the position of the two wires that act as aerials very important? Providing they are not touching other electrical wires/articles, can they face the same direction?

[Bob Burton]

Isn't the idea that they should face in different directions, perhaps at 90 degrees,  so that both of them are never pointing directly at the transmitter which is the least optimal direction to receive a signal

[Denis Watkins]

The idea that twin aerials are fitted at 90° to each other Bas, is that both are not in a weak position at the same time.

The strongest reception is at 90° to the wire

And the weakest reception is end on to the wire although some signal can be detected.

A set up of parallel aerials will act as a single aerial with fades and drop outs at that time when the aerials are end on to your tranny.

Twin aerials really do double reliability of set at 90°.

As Bob says, while I was typing.

Edited October 14, 2022 by Denis Watkins

[MattyB]

The transmitter aerial should be parallel and not collinear with at least one of the receiver's antenna(s). That means for most the aerials should be positioned 90 degrees apart (or thereabouts, the exact angle isn't critical). Of course that's not the end of it - should both aerials be aligned along the length the fuselage, one vertical and one along the fuselage, or both vertical? The answer depends on the model type; if it spends most of its time flying horizontally place both along the line of the fuselage and have my TX aerial horizontal; if it's an aerobatic type I go with one up, one along (and again the TX aerial horizontal).

[Basil]

Thank you, there is little room for an exact 90 degs. Do they have to be straight, could they bend/curve whilst trying to optimise there direction. Many thanks Bas

[Martin Harris - Moderator]

There’s no substitute for being straight and at 90 degrees to each other.  What are they going in that makes it difficult to achieve this?  If it’s not vaguely scale shaped and has a tiny fuselage, perhaps have them sticking out externally?

[Don Fry]

Basil, just to be accurate, as I have not seen reference to it, are you talking about the entire length of the aerial, or just the 25mm or so of bare wire at the end. That 25mm at the end is the aerial, the rest is just wire

[leccyflyer]

Bear in mind that the aerials should be at 90 degrees to each other, but that doesn't mean that has to bear any relationship to the datum on the aeroplane. So long as the aerials are orientated in different planes at 90 degrees to each other, that should be optimal. 

[Basil]

I dont have the height or width to spread out the wires.135mm long .Bas

[leccyflyer]

The bits that need to be at 90 degrees to each other are the silvery bits at the end of the aerials, with the outermost insulation removed. The rest of the aerial is just the co-axial cable to join those end bits to the receiver.

[J D 8]

 As Don says above it is the last bit of bare wire at the end that's the aerial, the rest can be curved to make them be as near as possible 90 degrees to each other.

   Leccyflyer got there first

Edited October 15, 2022 by J D 8
more info

[MattyB]

2 hours ago, leccyflyer said:

Bear in mind that the aerials should be at 90 degrees to each other, but that doesn't mean that has to bear any relationship to the datum on the aeroplane.

That is true, but if you have both along the fuselage length then the TX aerial should be in the same plane i.e. horizontal. Similarly if both aerials are pointing upwards (I.e if you looked from the front you could see them in a V shape) then the Tx aerial should be vertical.

[leccyflyer]

My TX aerial is horizontal, as in the manual.  That definitely is not varied for each model. My aeroplanes tend to adopt different orientations when they are in flight, probably averaging towards the horizontal during the course of the flight. Typically I'd have one rx aerial along the fuselage length and the other aerial up or down in a vertical plane. 

[John Wagg]

Depending on the model I drill pin holes in the fuselage and poke the wires out the side, top or bottom. 

[Engine Doctor]

I wrap some control snake inner with masking tape then glue it to the fuz to support and hold the aerial in position. The aerial slides easily through the snake inners for removal , maintenance etc.

[Basil]

Whats been said , that its only the bare /silvery bit thats the aerial put things in a whole new light. I have been under the impression that it as all of the wire, insulation and all.

There are 4 plus inches in to total, difficult to find the room for that at 90degs. Now I only need say about one  inch at 90degs oppossed makes things a whole lot more easy.

One more point what about proximatey to servos etc.I to have been trying tubes to guide/support the aerial, plastic straws seem good.

Many thanks to all those that took the time to reply.THANKS.

Bas

[FlyinFlynn]

Whilst it is true that it is only the end of the 4" 'antenna' that it the active part it is still important to get that active part away from the electronics of the receiver and, in fact, everything else as well -  as much as possible -  so sticking it out of the fuz isn't the worst idea but it is vulnerable to damage there.

[John Lee]

For gliders I generally stick them to the outside and the adhesive tape protects them. It's not obvious from the photo but in 3 dimensions they end up about 90 degrees apart and I have never had the slightest problem in the years I have been using this method.

 

 

 

[Martin Harris - Moderator]

My solution was to knock up a design for my 3D printer which ensures my aerials are always in ideal orientation to each other. A small cable tie holds the feeder cables and it can be screwed or fixed to the fuselage with velcro. 

The only drawback is if you are mounting aerials in something which has a large amount of signal blanking - big engine, large motor, areas of carbon fibre etc. then rather than this method it’s better to use the length of the feeder cables to diversify the position of each “whisker” to remote locations. 

[J D 8]

               Lost control of a park fly type the other day. Its receiver was of the short range single aerial type. Never had a problem with it in many flights, but inspection showed the aerial had come unstuck from its normal place and dropped down between the carbon rods to the tail surface's.