90 Antenna Elbow To Change Antenna Position

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My IRC600mw Vid TX is mounted underneath on the belly of the phantom with the cloverleaf fatshark sticking straight out the back. I was bending it 90 degrees to get it to point straight down for better transmission coverage. I want to position the antenna lower, but I like the balance of the phantom and don't want to mount the TX on the leg.

I was thinking of getting a 90 degree antenna elbow adapter so the cloverleaf will point straight down from the TX's current position. Such as this one...
http://www.hobbyking.com/hobbyking/store/catalog/FR90DEGA.jpg

Here's my question...

By adding another connection between the TX and the cloverleaf, is it possible that I might be sacrificing a small bit of transmission power? as compared to just remounting the TX on the leg and not using a 90 degree connector?

Thank you

JB
 
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My IRC600mw Vid TX is mounted underneath on the belly of the phantom with the cloverleaf fatshark sticking straight out the back. I was bending it 90 degrees to get it to point straight down for better transmission coverage. I want to position the antenna lower, but I like the balance of the phantom and don't want to mount the TX on the leg.

I was thinking of getting a 90 degree antenna elbow adapter so the cloverleaf will point straight down from the TX's current position. Such as this one...
http://www.hobbyking.com/hobbyking/store/catalog/FR90DEGA.jpg

Here's my question...

By adding another connection between the TX and the cloverleaf, is it possible that I might be sacrificing a small bit of transmission power? as compared to just remounting the TX on the leg and not using a 90 degree connector?

Thank you

JB
Typically, every connector in a transmission line adds 3dB of loss.
 

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Anytime you insert something in the path there will be 'insertion losses' primarily due to power reflections back to the Tx..
These will generally be about a dB or two for good quality connectors however the improved performance by optimizing your antenna's position or alignment may actually overcome any loss(es).
 
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Thank you guys for the info...

So really my next question is... Do I give up 1-3 db in power and add the adapter, or do I just reposition the TX on one of the legs with the cloverleaf pointed straight down..

Anyone have a link to a really good quality adapter?
 
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Typically, every connector in a transmission line adds 3dB of loss.
Are you forgetting a decimal point there Steve? The estimated loss for a SMA connector is 0.5db.
 
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My IRC600mw Vid TX is mounted underneath on the belly of the phantom with the cloverleaf fatshark sticking straight out the back. I was bending it 90 degrees to get it to point straight down for better transmission coverage. I want to position the antenna lower, but I like the balance of the phantom and don't want to mount the TX on the leg.

I was thinking of getting a 90 degree antenna elbow adapter so the cloverleaf will point straight down from the TX's current position. Such as this one...
http://www.hobbyking.com/hobbyking/store/catalog/FR90DEGA.jpg

Here's my question...

By adding another connection between the TX and the cloverleaf, is it possible that I might be sacrificing a small bit of transmission power? as compared to just remounting the TX on the leg and not using a 90 degree connector?

Thank you

JB
I have inserted a 90 degree SMA adapter to get my cloverleaf antenna pointing straight downwards. I did not notice any effect on the fpv range. For me, the purpose of the adaptor was to have less vibration on the antenna, and from the antenna into the transmitter. Solder joints do not like vibrations so i was expecting problems in the transmitter.
 
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I have inserted a 90 degree SMA adapter to get my cloverleaf antenna pointing straight downwards. I did not notice any effect on the fpv range. For me, the purpose of the adaptor was to have less vibration on the antenna, and from the antenna into the transmitter. Solder joints do not like vibrations so i was expecting problems in the transmitter.
I had done the same thing with my TX and a 0.5db loss in signal isn't noticeable.
IMG_1554.jpg
 
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I was encountering an issue similar to the one you have. When I had the phantom flying away (the antenna pointing towards me) the FPV signal range was very good, when I turned the copter, to return home (the antenna now facing away from me) I lost fpv signal altogether. I fitted a 90 deg elbow and had the antenna pointing straight down, this gave me the desired result where I had more fpv from the phantom regardless of its position relative to where I was.
 
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Typical losses on a 90 degree SMA through adapter @ 5.8GHz are 1.5-3 db. You also need to consider the VSWR as well.

That being said, compared to over-bending the coax, these loses are quite acceptable. the lowest loss solution would be to fit a 90 degree plug, as the losses on this will be around half those of an adapter and with better VSWR performance as well.
 
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We could argue this all day, but 90 degree adapters have a higher VSWR according to their spec sheets. You need to consider the whole length of the transmission line, as you are in effect, altering the impedance "seen" by the transmitter. This can reduce the total available power at the antenna.

The insertion loss is directly proportional to the frequency. It also assumes a perfect environment, so any contamination or moisture will affect things as well.

As I originally said, bending a piece of coax beyond its minimum radius to get a cloverleaf pointing down is more harmful, as this will also have a detrimental effect on the performance of the transmission line as a whole.
 
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You need to consider the whole length of the transmission line, as you are in effect, altering the impedance "seen" by the transmitter. This can reduce the total available power at the antenna.
.
I don't know what the antenna in question is but the characteristic impedance of the feed line must be different than the antenna impedance? Otherwise the length of transmission line would not matter as far as SWR. Have more info on the antenna and coax?
 
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Typical losses on a 90 degree SMA through adapter @ 5.8GHz are 1.5-3 db. You also need to consider the VSWR as well.

That being said, compared to over-bending the coax, these loses are quite acceptable. the lowest loss solution would be to fit a 90 degree plug, as the losses on this will be around half those of an adapter and with better VSWR performance as well.
I don't know where you got those losses for SMA 90° elbow connector but I got mine from the manufacture. As far as VSWR the wattage and length of that antenna are so minute it couldn't be measured on an SWR meter.
 
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So I finally had some time and picked up a high quality 90 degree adapter..

I am consistently getting a much cleaner signal all the way around. Regardless of phantom attitude and yaw angle to the transmitter, the video signal is clean with no hickups or dropouts. I have tested out to a clean line of sight at 2000 meters and the signal is much more consistent than before..

I am going to take a guess that a good antenna position (as far away from any objects on the phantom) is a key point here.

The current antenna position is pointing straight down off the back of the phantom and is currently lower than the skids. I use my pelican case to launch it with the phantom backed up to the edge of the case so it sits on the skids without the antenna getting in the way.. I always hand recover it as it wont sit flush on the ground.
 
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We could argue this all day, but 90 degree adapters have a higher VSWR according to their spec sheets. You need to consider the whole length of the transmission line, as you are in effect, altering the impedance "seen" by the transmitter. This can reduce the total available power at the antenna.

The insertion loss is directly proportional to the frequency. It also assumes a perfect environment, so any contamination or moisture will affect things as well.

As I originally said, bending a piece of coax beyond its minimum radius to get a cloverleaf pointing down is more harmful, as this will also have a detrimental effect on the performance of the transmission line as a whole.

It's not a CB big buddy. 10-4. How's your swer...

Happily use 90 degree SMA adaptors. On high power microwave gear Ham radio gear.

If your elbow changes the impedance or vswr teen you need a better connector. The losses. From the spec sheet I provided above.

SMA SPECIFICATIONS
Electrical
Impedance 50 Ohm
Frequency Range
.141" & .085" O.D. Copper Jacket Semi-Rigid Cable 0-18 GHz
Flexible Cables 0-12.4 GHz
Voltage Rating
RG-55, 58, 141, 142, 223, 303 500 volts peak
RG-122, 174, 188, 316 375 volts peak
Dielectric Withstanding Voltage (max.)
.141" & RG-58 Group 1000 VRMS
.085" & RG-316 Group 750 VRMS
VSWR for Straight Connectors
.141" O.D. Copper Jacket Cable 1.05 + .005 f (GHz)
RG-55 Group 1.15 + .011 f (GHz)
RG-122 Group 1.15 + .02 f (GHz)
RG-178 Group 1.20 + .025 f (GHz)
VSWR for Angle Connectors
.141" O.D. Copper Jacket Cable 1.10 + .01 f (GHz)
RG-55 Group 1.15 + .02 f (GHz)
RG-122 Group 1.15 + .03 f (GHz)
RG-178 Group 1.20 + .03 f (GHz)
Insulation Resistance 5000 MΩ
Contact Resistance
Center Conductor 2.0 mΩ
Body 2.0 mΩ
Braid to Body 0.5 mΩ
RF Leakage -60 dB min
Insertion Loss .03 sqrt(f(GHz)) dB max


ImageUploadedByTapatalk1430131231.509945.jpg



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Greetings vk3bq de kd0zv

73
 
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It's not a CB big buddy. 10-4. How's your swer...

Happily use 90 degree SMA adaptors. On high power microwave gear Ham radio gear.

If your elbow changes the impedance or vswr teen you need a better connector. The losses. From the spec sheet I provided above.

SMA SPECIFICATIONS
Electrical
Impedance 50 Ohm
Frequency Range
.141" & .085" O.D. Copper Jacket Semi-Rigid Cable 0-18 GHz
Flexible Cables 0-12.4 GHz
Voltage Rating
RG-55, 58, 141, 142, 223, 303 500 volts peak
RG-122, 174, 188, 316 375 volts peak
Dielectric Withstanding Voltage (max.)
.141" & RG-58 Group 1000 VRMS
.085" & RG-316 Group 750 VRMS
VSWR for Straight Connectors
.141" O.D. Copper Jacket Cable 1.05 + .005 f (GHz)
RG-55 Group 1.15 + .011 f (GHz)
RG-122 Group 1.15 + .02 f (GHz)
RG-178 Group 1.20 + .025 f (GHz)
VSWR for Angle Connectors
.141" O.D. Copper Jacket Cable 1.10 + .01 f (GHz)
RG-55 Group 1.15 + .02 f (GHz)
RG-122 Group 1.15 + .03 f (GHz)
RG-178 Group 1.20 + .03 f (GHz)
Insulation Resistance 5000 MΩ
Contact Resistance
Center Conductor 2.0 mΩ
Body 2.0 mΩ
Braid to Body 0.5 mΩ
RF Leakage -60 dB min
Insertion Loss .03 sqrt(f(GHz)) dB max


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Do you think he got the message in the UK.
 

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