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Using a Deans Antenna on RX

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Old 08-04-2005, 09:36 AM
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Rcpilot
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Default Using a Deans Antenna on RX

I've got several little 40-size planes, and the darn antenna wire is always too long. I'm always racking my brain trying to figure out a way to route the long antenna lead and secure it to the plane without letting it get damaged.

I am NOT willing to just let it flap around in the breeze behind the plane. They get ripped up and damaged that way--and I don't like replacing amtennas.

Anyone ever used one of these:
http://www2.towerhobbies.com/cgi-bin...?&I=LXKX48&P=0

I could cut off the existing antenna and mount this little antenna on the top of the turtledeck on most of my planes.

Any problems using these? Hows the reception?

Thanks
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Old 08-04-2005, 10:04 AM
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dant-RCU
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Default RE: Using a Deans Antenna on RX

I have been using them for over 10 years in everything from small electrics to big scale and never had a problem at all. They are easy to configure and easy to mount.

Dan
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Old 08-04-2005, 10:26 AM
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Default RE: Using a Deans Antenna on RX

if they're good enough for jets then they'll be fine for everything else.

for a couple of years now i've been using the DIY "fly wire" which is basically the same as every other base-loaded antenna out there. no problems yet



dave
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Old 08-04-2005, 11:00 AM
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Default RE: Using a Deans Antenna on RX

Thanks guys.

I'm gonna order 3 or 4 of them today.

Does the length of the existing wire antenna effect the range?

It says that your supposed to cut off the existing antenna wire and leave it 4--10" long. Then solder on the Deans antenna. Is that just for mounting purposes--and you cut it off at any length you need?

Or do I need to cut the antenna wire off at a specific length for best reception?
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Old 08-05-2005, 03:45 PM
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Default RE: Using a Deans Antenna on RX

NO.

You cut the antenna to leave a length of 4 to 10 inches. It is not for mounting purposes per se - has to do with how the base loaded antenna plus the remaining antenna wire length is "seen" by the receiver. Normally I cut mine to 6 inches.

Dan
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Old 08-06-2005, 06:52 AM
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daven
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Default RE: Using a Deans Antenna on RX

Heres a trick the racers have been using for years.

Cheaper than a deans and you don't have to cut the antenna.

http://www.darrolcady.com/Racing_Inf...ch/Antenna.htm
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Old 08-06-2005, 08:25 PM
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Default RE: Using a Deans Antenna on RX


ORIGINAL: dant-RCU

NO.

You cut the antenna to leave a length of 4 to 10 inches. It is not for mounting purposes per se - has to do with how the base loaded antenna plus the remaining antenna wire length is "seen" by the receiver. Normally I cut mine to 6 inches.

Dan
I've been doing a bunch of reading past posts on this subject.

It appears to me that I might need to "tune" the length of my antenna wire to get the maximum range out of the Deans base loaded antenna.

Seams some guys hate them and can't make them work. Poor range checks.

Other guys love them, great range checks and reception.

But, noone is elaborating on whether or not they had to cut the antenna off a little at a time to get it all "tuned".

I guess I'll start off with my antenna wire 10" long and keep range checking and cutting the wire off untill I get the max range check.
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Old 08-08-2005, 08:07 AM
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Default RE: Using a Deans Antenna on RX

I have never (NEVER) had any reason to play around trying to "tune" anything using the Deans antenna. All I know is that I have plenty of range (I am sure it is much further than I can see) and have never had problem that I could blame on my antenna. What do these people "tune" for anyhow? Maybe they want to get a ground range of 80 feet vs 78 for all I know.

There are people who seem to have trouble with everything they touch. If I really was worried about "things that are junk or don't work or are problems" that I read about in these forums; then I wouldn't be using anything I have now!!

No, I just cut the antenna, add the Deans and go fly. I leave it to the antenna engineers to have done the design. After all, it is they who say to "cut the antenna to a length of 4 to 10 inches".

My .05

Dan
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Old 08-11-2005, 08:51 PM
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Default RE: Using a Deans Antenna on RX

Antenna length is a tradeoff between signal level and convenience. I am a strong supporter for longer antennas which have more radiation resistance and therefore "pump" more signal into the air. same applies to receive antennas. But like I said, it's a tradeoff
....a helicopter works fine with a small whip on Rx and a rubber duck on Tx ....but they are generally not far away.
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Old 08-12-2005, 07:30 AM
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Default RE: Using a Deans Antenna on RX

I lost a airplane due to a Deans antenna, inspite of what has been said, even Deans says their antenna does not have the range of the long wire antenna. "You pays your money and you takes your chances." I do not recommend it unless you have no other solution.

Most folks drill a hole aft of the wing mount in the center of the fuselage and string it out to the vertical tail. use a rubber band to provide tension. Works just fine and does the job. If it is a really big airplane string it out inside the aircraft.

It is up to you. Deans antennas work just not as good.

Cheers,

Chip
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Old 08-12-2005, 07:55 AM
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Default RE: Using a Deans Antenna on RX

http://www.uoguelph.ca/~antoon/gadgets/flywire.htm This is the [flywire] that Zagnut was talking about. I have them in half a dozen different rcvrs. with no problems. I was sceptical at first but after three yrs. I'm convinced Most of my prangs are from flying a little over the edge
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Old 08-12-2005, 08:22 AM
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Default RE: Using a Deans Antenna on RX

ORIGINAL: apteryx

Antenna length is a tradeoff between signal level and convenience. I am a strong supporter for longer antennas which have more radiation resistance and therefore "pump" more signal into the air. same applies to receive antennas. But like I said, it's a tradeoff
....a helicopter works fine with a small whip on Rx and a rubber duck on Tx ....but they are generally not far away.
And along those lines, I happened across this study of antenna length: http://www.rc-cam.com/ant_exp.htm
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Old 08-12-2005, 09:27 PM
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Default RE: Using a Deans Antenna on RX

Here is an old ham's input............

RC-CAM knows what he's talking about in the above article. The way to improve the signal to the receiver without using active components like MMICs (and those amplify noise too) is to have the longest, resonant antenna possible in the plane. In another RCU discussion I covered optimum orientation of the transmitter whip antenna relative to the receiver antenna. Most receiver frontends are designed for 50-100 ohm imput impedance at the desired frequency. The 38-41 inch wire antennas work very well at 72 Mhz because the half wavelength at 72Mhz is roughly that and thus provides the proper impedance match. Wavelength in inches is (5905)/(Frequency in Mhz) ....so for Ch 30 (72.39Mhz) the length would be 82" for fullwave and 41" for a halfwave (the actual antenna length is about 5% or so less). Also note that some receivers use base loading coils and require a shorter ...like 36" antenna. If you compromise and go to an even shorter antenna for asthetics, the CORRECT coil you wind on the soda straw, dowel, etc and put at the base, middle, or wherever allows the impedance of the shorter antenna to still look like 50-100 ohms to the receiver. BUT, you will not receive as well as a full length 1/2 wavelength antenna. Now, some may say their super whoopty-do antenna is better ....maybe when matched between a resonant shorter antenna and a non-resonant longer antenna. But, if you match a proper resonant 1/2 wavelength antenna against a shorter resonant antenna, the 1/2 wavelength will win. If you need the convenience of a shorter antenna, by all means go there .....just be sure you know your flying range has been decreased some.
If the antenna is too long, leave it trailing behind the plane. If you fold it back on itself, run Zs or whatever, you effectively shorten the antenna and the impedance is no longer 50-100 ohms.
Resonant Tx antennas are very important (more power, less SWR, less transistor heating) but resonant receive antennas are important too if you really want to grab the max signal out of the air.
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Old 05-24-2009, 08:59 PM
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Default RE: Using a Deans Antenna on RX

In the coil/wire build for a loaded antenna, does it matter which end of the coil is soldered to what?
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Old 05-25-2009, 12:06 PM
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Default RE: Using a Deans Antenna on RX

No, I just cut the antenna, add the Deans and go fly. I leave it to the antenna engineers to have done the design. After all, it is they who say to "cut the antenna to a length of 4 to 10 inches".
Yup!....Used to use'um in everything from 2 meter pattern to 34% with no issues.....Before I switched to 2.4....FWIW
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Old 05-29-2009, 08:50 AM
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Default RE: Using a Deans Antenna on RX


ORIGINAL: Rcpilot

I've got several little 40-size planes, and the darn antenna wire is always too long. I'm always racking my brain trying to figure out a way to route the long antenna lead and secure it to the plane without letting it get damaged.

I am NOT willing to just let it flap around in the breeze behind the plane. They get ripped up and damaged that wayand I don't like replacing amtennas.

Anyone ever used one of these:
http://www2.towerhobbies.com/cgi-bin...?&I=LXKX48&P=0

I could cut off the existing antenna and mount this little antenna on the top of the turtledeck on most of my planes.

Any problems using these? Hows the reception?

Thanks
With all that money you have laying around Chris, you could just convert to 2.4 and be done with it!
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Old 05-29-2009, 10:24 AM
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Default RE: Using a Deans Antenna on RX


ORIGINAL: tande

No, I just cut the antenna, add the Deans and go fly. I leave it to the antenna engineers to have done the design. After all, it is they who say to "cut the antenna to a length of 4 to 10 inches".
Yup!....Used to use'um in everything from 2 meter pattern to 34% with no issues.....Before I switched to 2.4....FWIW
I too have never had any issues for many years now with simply cutting to about 6 inches and mounting.

Skarn
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Old 05-29-2009, 01:20 PM
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Default RE: Using a Deans Antenna on RX

Fortunately, most modern receivers are good enough to let us use the shortened antennas, no matter what you call them.  However, Mr. RC Cam's write up is "Right On".  You will loose range anytime you shorten that antenna, it is just that on most current good receivers, you still have enough range to safely fly close-by.  In almost all cases, you will cut your range in half, more probably by 3/4th the range you have with the original antenna.  It is not only the fact that you loose range due to missmatching of impedances but also due to loss of capture area.  You will loose 1/2 your range for every 3DB loss in signal power.
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Old 05-29-2009, 02:17 PM
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Default RE: Using a Deans Antenna on RX

You guys realize this thread began 4 years ago? Before 2.4 GHz was in use for RC?

Just asking
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Old 05-29-2009, 02:39 PM
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Default RE: Using a Deans Antenna on RX


ORIGINAL: bruce88123

You guys realize this thread began 4 years ago? Before 2.4 GHz was in use for RC?

Just asking
Nope!
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