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Rx Antenna Routing - effective antenna length?

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Old 01-22-2008, 12:43 AM
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somegeek
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Default Rx Antenna Routing - effective antenna length?

Regarding Rx antennas, Balsabuster2003 sent me a great reference URL - R/C Antenna Experiments - Does Rx Antenna Length Really Matter? Some great tests and results with different antenna routing and shortening method loss results.

Forgive my ignorance here...

Regarding an antenna's effective length... I'd read and the above confirms that if you double back and antenna, you cut the length and reception power in half... what if you don't double it back? Is the longest straight path of a 1-meter antenna considered the effective antenna length? In my SSE, there is about six inches of curved antenna from the Rx until it's straight down the fuselage with about 6" hanging off the back which is curved. Is the straight portion considered the effective antenna length?

On a Stryker I build recently, there were three straight legs to the antenna path, 8", a 45ΒΊ turn, 16", a 30ΒΊ turn and then a 14" leg. What would the antenna length be with this setup? Would the 16" length be the effective antenna length?

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Old 01-22-2008, 11:27 AM
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Rodney
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Default RE: Rx Antenna Routing - effective antenna length?

There is no simple answer to your question. Many factors effect the effective length. Folded back on itself is a simple answer, yes the effective length is the longest straight section. If it is coiled around some object like a dowel or straw, the distance between coils, size of the wire (the gage) and where within the total length the coil is placed all effect the answer. To be exact, you need to know the resulting contribution of the inductance, capacitance and length of the various elements. In short, usually any modification to the antenna from the factory settings will reduce the effective range of the receiver. How much? Only a range test will give you the correct answer.
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Old 01-22-2008, 03:06 PM
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Default RE: Rx Antenna Routing - effective antenna length?

Hitec sends a bobbin to wind the antenna around to shorten the length. I have not noticed any range difference when using the bobbin. If you do this, do not overlap any of the winds, the bobbin is about 1" wide.
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Old 01-22-2008, 07:30 PM
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Default RE: Rx Antenna Routing - effective antenna length?

I have the bobbins but have not yet had to use them. Might try this as the Hitec guy I spoke with suggested they create a bit of a coil effect.

Range difference will probably not be noted since this is a 1/2A and I won't be flying this further than I can see it.

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Old 01-23-2008, 03:06 AM
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Default RE: Rx Antenna Routing - effective antenna length?

refer to sub section "Antenna - Rubber Duckie, Micro & Whip Flywire - replace long aerials with loaded base antenna" at Alan's Hobby, Model & RC FAQ Web Links in particular Bobbin - What is purpose/effect of the Hitec Antenna Bobbin
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