Nigel Heather Posted June 6, 2022 Share Posted June 6, 2022 I am going to make an antenna mount for my Futaba FASST receiver - basically a small mount with two plastic tubes at 90 degrees to keep the antennas tidy and at right angles - it will be fixed to the outside of the plane. Question - so imagine the tubes make a right angle V - is it okay for this V to mounted flat on the top of the fuselage or is it better if it were tilted up at 30 or 45 degrees. I'm guessing it doesn't matter that much as on past aircraft they have just be stuffed inside the fuselage out of sight not even with proper 90 degree orientation - but thought I'd check with the experts here. Cheers, Nigel Quote Link to comment Share on other sites More sharing options...
Dickw Posted June 6, 2022 Share Posted June 6, 2022 Flat on top of a fuselage works but probably best not flat 'against' the fuselage if it is carbon or some other conducting material. The attached photo shows an arrangement that worked OK for me in a carbon fuselage. Dick Quote Link to comment Share on other sites More sharing options...
Dad_flyer Posted June 6, 2022 Share Posted June 6, 2022 The underlying theory is that an antenna has a dead zone in the direction the wire is pointing. So a second antenna that is not pointing in exactly the same direction has a different dead zone. 90degrees is best, but the 90 degree pair can then be in any orientation. 1 Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted June 6, 2022 Share Posted June 6, 2022 (edited) With a carbon fuse I'd be sorely tempted to put one antenna out 45 degrees either side, to avoid the situation where both antennae are capable of being shielded from the transmitter by the carbon fibre fuse. Otherwise I agree with Dad_flyer's explanation, with both antennae as well clear as possible and not parallel to anything that conducts electricity. Edited June 6, 2022 by Allan Bennett Quote Link to comment Share on other sites More sharing options...
Nigel Heather Posted June 6, 2022 Author Share Posted June 6, 2022 Thanks, the fuselage in this case is polystyrene, not carbon fibre. I like the idea of ‘flat’ as it is less likely to get knocked but not mind pitching it at 30 degrees. But, personally, I doubt it will make any difference. Cheers, Nigel Quote Link to comment Share on other sites More sharing options...
gangster Posted June 9, 2022 Share Posted June 9, 2022 It cannot be that critical. We are talking about a moving receiver. And we are standing below the model as well And a very short wavelength. 90 degrees to what and in which plane, not meant to be a pun plane meaning x or y axis. I have seen modellers get their knickers in such a twist about this to the extent that they pull their aerials into all sorts of positions to achieve the legendary 90 degrees . These aerials are delicate things Usually the same modellers who have the problems. Quote Link to comment Share on other sites More sharing options...
Dad_flyer Posted June 9, 2022 Share Posted June 9, 2022 It is indeed not that critical. The dead spot is straight along the antenna wire, so as long as there is some angle between them the two antennas will cover each other's dead spot. The furthest from the same direction is 90degrees, so that is best, but it is not critical. 90 degrees to eachother has no reference to the model or receiver, it can be in any plane. Thinking about the best reception rather than the dead spot, the best reception is more like a ring donut with the antenna pointing up the hole. Two of those at 90degrees makes something like a sphere (or a jam donut). Reception is pretty much the same in all directions in that case, which is what we would like. Everyone managed with one antenna on 35MHz... Quote Link to comment Share on other sites More sharing options...
Frank Day Posted June 9, 2022 Share Posted June 9, 2022 I just place them at 90deg and as far apart as possible and also try to put them on the underside; probably makes little or no difference but thats where most of us will be. Or if its difficult to position just use the antennaless options, havent had an issue and just poke them wherever but away from the usual signal affecting materials. Quote Link to comment Share on other sites More sharing options...
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