Antennas that bend

[STOOPIDMONKEY]

I have always been curious about this, but never asked... On some transmitters there is an antenna that you can rotate and bend, what is it for? What is the best way to have the antenna during flight? I can understand the bend for easy storage but is there a greater purpose?

[rc-eflyer]

RE: Antennas that bend

I have always been curious about this, but never asked... On some transmitters there is an antenna that you can rotate and bend, what is it for? What is the best way to have the antenna during flight? I can understand the bend for easy storage but is there a greater purpose?

It's to orient the antenna in a more vertical postion (vertical polarization) to give better range mostly. So you should adjust it by how you hold your radio so it points mostly straight up. Honestly, I personally forget to do this al the time and have never had problems YMMV.

One funny thing I found once on a small inexpensive quad that came with a small transmitter was, the antenna was just a piece of plastic with that elbow but the ACTUAL antenna was just a short piece of wire inside the transmitter :rolleyes: .

Steve

[CT]

RE: Antennas that bend

I have always been curious about this, but never asked... On some transmitters there is an antenna that you can rotate and bend, what is it for? What is the best way to have the antenna during flight? I can understand the bend for easy storage but is there a greater purpose?

As strange as it may seem, I had experienced various minute brownouts while using my DX-6, and noticed that most pilots were using their transmitter with the antennae at a 90* angle. After some research I moved the antennae this way and behold, no more brownouts! My new DX-9 has a fixed antennae which is placed at various angles inside to optimize reception. It is funny to think that problems like these are so frustrating and can be solved so easily. Thats the beauty of these boards, offering exceptional education and experience.
CT

[WintrSol]

RE: Antennas that bend

How you adjust it depends on how the antennas are mounted in the model. You want the transmitter antenna to lie in the same plane as at least one receiver antenna (if there are more than one), for as much of the flight as possible. It also should be orientated to that the side of the transmitter antenna is directed at the model, not either end. I usually mount my receiver antennas horizontally in the model, at ~90 degrees to each other, so I have my transmitter antenna along the top of the case; this is because the model is seldom vertical, so I get best signal this way. If you fly 3D, though, you may want to set them up differently

[rc-eflyer]

RE: Antennas that bend

How you adjust it depends on how the antennas are mounted in the model. You want the transmitter antenna to lie in the same plane as at least one receiver antenna (if there are more than one), for as much of the flight as possible. It also should be orientated to that the side of the transmitter antenna is directed at the model, not either end. I usually mount my receiver antennas horizontally in the model, at ~90 degrees to each other, so I have my transmitter antenna along the top of the case; this is because the model is seldom vertical, so I get best signal this way. If you fly 3D, though, you may want to set them up differently

I agree that ideally you want the polarizations to line up BUT to get the best all around performance from your TX you have to consider how the signal is propagated from the antenna. Imagine a huge doughnut with your antenna pointing right through the hole. The signal strength is represented by this doughnut. Therefor it is weakest pointing straight out from the antenna tip. This is why you never point your antenna straight at the plane. So generally speaking this would be if you fly directly over yourself (and we all known that sucks). With the antenna straight up you have better range in a 360 degree horizontal pattern around you which (hopefully) is where the plane is. This used to be much more important with the 72Mhz than with the 2.4Ghz stuff we use now(it multi paths, bounces around) more. Again, just speaking as a general rule, YMMV.

Steve

[WintrSol]

RE: Antennas that bend

How you adjust it depends on how the antennas are mounted in the model. You want the transmitter antenna to lie in the same plane as at least one receiver antenna (if there are more than one), for as much of the flight as possible. It also should be orientated to that the side of the transmitter antenna is directed at the model, not either end. I usually mount my receiver antennas horizontally in the model, at ~90 degrees to each other, so I have my transmitter antenna along the top of the case; this is because the model is seldom vertical, so I get best signal this way. If you fly 3D, though, you may want to set them up differently

I agree that ideally you want the polarizations to line up BUT to get the best all around performance from your TX you have to consider how the signal is propagated from the antenna. Imagine a huge doughnut with your antenna pointing right through the hole. The signal strength is represented by this doughnut.  Therefor it is weakest pointing straight out from the antenna tip. This is why you never point your antenna straight at the plane. So generally speaking this would be if you fly directly over yourself (and we all known that sucks). With the antenna straight up you have better range in a 360 degree horizontal pattern around you which (hopefully) is where the plane is. This used to be much more important with the 72Mhz than with the 2.4Ghz stuff we use now(it multi paths, bounces around) more.  Again, just speaking as a general rule, YMMV.

Steve

Part of the reason 72MHz antennas are pointed upwards is the fact they are ~1 meter long; kind of an issue trying to lean that sideways. I always face my model with my transmitter, so don't need the width of the 'doughnut' a vertical antenna provides; if the antenna were fixed to a surface, then vertical would be far superior. Also, at the range I fly, absolute signal strength isn't an issue, either - I try to stay less then 1/2 mile from my models.

[rc-eflyer]

RE: Antennas that bend

How you adjust it depends on how the antennas are mounted in the model. You want the transmitter antenna to lie in the same plane as at least one receiver antenna (if there are more than one), for as much of the flight as possible. It also should be orientated to that the side of the transmitter antenna is directed at the model, not either end. I usually mount my receiver antennas horizontally in the model, at ~90 degrees to each other, so I have my transmitter antenna along the top of the case; this is because the model is seldom vertical, so I get best signal this way. If you fly 3D, though, you may want to set them up differently

I agree that ideally you want the polarizations to line up BUT to get the best all around performance from your TX you have to consider how the signal is propagated from the antenna. Imagine a huge doughnut with your antenna pointing right through the hole. The signal strength is represented by this doughnut.  Therefor it is weakest pointing straight out from the antenna tip. This is why you never point your antenna straight at the plane. So generally speaking this would be if you fly directly over yourself (and we all known that sucks). With the antenna straight up you have better range in a 360 degree horizontal pattern around you which (hopefully) is where the plane is. This used to be much more important with the 72Mhz than with the 2.4Ghz stuff we use now(it multi paths, bounces around) more.  Again, just speaking as a general rule, YMMV.

Steve

Part of the reason 72MHz antennas are pointed upwards is the fact they are ~1 meter long; kind of an issue trying to lean that sideways. I always face my model with my transmitter, so don't need the width of the 'doughnut' a vertical antenna provides; if the antenna were fixed to a surface, then vertical would be far superior. Also, at the range I fly, absolute signal strength isn't an issue, either - I try to stay less then 1/2 mile from my models.

I hope you don't think my post was arguing with your methods, it was meant as a general statement of what I was taught as a "best practice". As far as the 72 Mhz antenna, at that time most receiver antennas were a rather long piece of wire strung horizontally so holding the TX in a normal fashion they pretty much lined up. If what you do works for you that's great too. Happy Flying!

Steve