Modding RTF quad transmitter antennas

B3Master

B3Master

Well-Known Member
Howdy all I have a X5C-1 V6 and already noticed some blind sports or drop outs at random spots while flying and I plan on enhancing the stock transmitter antenna. But the following question apply to all quads not just the syma x5c,

From reading around I see that 2.4Ghz frequency requires antennas in the lengths of the multiple of 31.25mm (quarter wave length), the more accurate the better the output.

My first question is when increasing the antennas length how much of an increase should we expect if we ONLY increase the wire length from quarter wave length, to half wave length, to full wave length? (single wire no coax)

Second question to complete the first, does wire thickness we choose affect the increase? 24ga 18ga 16ga? Multi strand or single strand? any effect?

Third question, if we want to improve further range and install a coax wifi antenna soldered to signal and ground, how much of an improvement over full wave length single wire should we expect to get? is it worth the work? Would need to find a faulty wifi router at home or at the neighbors :rolleyes:
 
For 1 unless you are using fpv with the proper range as well the antenna mod is sort of overkill to an extent..Granted you can increase range above 100m but my guess is ,thats far away enough that you cant tell orientation of the quad to fly it back in by the naked eye. (Hence where the fpv comes into play.)

The wire length should already be 1/4 wave length (31.25mm)...if it isnt, then changing that is an improvement already.

The simple range mod is taking a UFL to Sp Rma pig tail and replacing the garbage antenna on the transmitter board and adding a +/- 3db to 5bd 2.4g antenna.

Ive seen some use smaller pig tails and some larger pigtails as far as gauge and it didnt seem to make a difference..im believing its more the length than anything.

Heres a well done "how to" on doing the range mod.
http://rcnerd.net/syma-x5c-transmitter-hack/
 
Somtimes one looses orientation up high, and it gets cought in high wind, and by the time you regain orientation the quad is loosing signal and cant be brought back. I use the alwsys bank left turn routine to regain orientation but need to have enough range to bring the quads back. either the quad will bank left and face me or it was facing me and needs to do a 360 and is at its furthest distance right before it actualy turns left then towards me. So more range will always bring it back.

Will putting a half or full wave length single wire give improvement? What sort of expectation?
 
Moving up to a 1/2 range antenna will narrow you signal a significant amount meaning the signal becomes more directional.

Imagine a glow around the antenna. A circle if you will...the higher the DB or the more range you increase it that circle starts to disappear from the tip of the antenna outward to the sides of the antenna..At some point if you pointed the tip of the antenna at the quad it wouldnt have any signal at all as the signal is now coming from the sides of the antenna signaling away from the quad...You would need to lay your antenna down horizontally using the signals now coming from the sides of the antenna to have any signal at all.

So to answer the question..Yes, 1/2 range will give you longer distance but a much narrower range of operation..You would basically have to never point the transmitter at the quad to not lose signal...You would always have to be to the side of the direction the quad is traveling in to not lose signal.

I suppose an easier way to understand is like the field of view on a camera...1/4 range would be a wide angle 180 degree lens and 1/2 range would be a narrow 80 degree view.
 
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So, the feild of broadcast becomes a doughnut with the hollow side being the tip if the antenna. But at 1/4 wavelength its sorta a globe still with no hollow side on the tip of the antenna?
 
That about sums it up...All your signal will be on the sides of the antenna basically at 1/2 range.

Most lay them down to keep a signal forward although, it will be much more narrow but stronger for better distance.

Just increasing the db of the antenna has the same effect...A 10db antenna on the transmitter should give more range than a 5db antenna.

A 5db antenna with 1/4 range on the receiver should be good for 100m or more..Im not sure why you would need more than that...Even flying as high as you can its a tiny spec in the air...Keep in mind the wind you feel on the ground is less than whats up high so if its windy below its not really a good idea to be flying it up high anyhows...lol
 
So, do the mods shown above..its cheap..maybe $10.00 in parts and a little soldering.

The X5C-1 is not really that powerful to fight wind..the programming isnt very aggressive giving enough pitch to do that.

If your x5c is stock you might be getting 30 meters at best...The range mod should make you happy.
 
You dont need to do anything to the antenna on the control board...that should be the proper 1/4 range length...just the antenna on the transmitter needs to be replaced.
 
Heres some links to what you need...you can shop for better prices if you want but these are the items needed.
http://www.ebay.com/itm/like/121592101830?ul_noapp=true&ul_ref=http%3A%2F%2Frover.ebay.com%2Frover%2F1%2F711-117182-37290-0%2F2%3Fmtid%3D1588%26kwid%3D1%26crlp%3D53601919689_324272%26itemid%3D121592101830%26targetid%3D124316380329%26rpc%3D0.20%26rpc_upld_id%3D56792%26rlsatarget%3Dkwd-124316380329%26device%3Dm%26mpre%3Dhttp%253A%252F%252Fwww.ebay.com%252Fulk%252Fitm%252Flike%252F121592101830%253Flpid%253D82%2526chn%253Dps%26adtype%3Dpla%26loc%3D21137%26poi%3D%26campaignid%3D239125209%26adgroupid%3D14978428809%26gclid%3DCO2uyMzG6cgCFYlafgod4bkItg%26srcrot%3D711-117182-37290-0%26rvr_id%3D920636519716&chn=ps&lpid=82

http://m.ebay.com/itm/NEW-FrSky-5dB-Module-Antenna-/231237971083?nav=SEARCH
 
B3Master said:
Will putting a half or full wave length single wire give improvement? What sort of expectation?
Click to expand...
Easy enough to try, simply tack on (solder) a piece of wire (the type of wire is not critical) to the end of the stock antenna, run it at an angle, and see how it works. Shoot for 62mm total length. May be a good idea to reinforce it at the PCB and at the tip using a dab of hot glue.

Syma_add_wire.jpg


If that don't seem to help (it has for many) then you can move on to other mods.
 
What other mods would you be referring to?...You only have the antenna mod on the transmitter...using the RP SMA cable is even longer than adding a piece of wire and, keeping it inside the transmitter...The rp sma mod gives gives you a "real" antenna poking up outside of the radio.
 
I am starting to think that having the antenna fully sideways from the point of contact on the board is the best possible but not feasable position as long as we are personally having the remote (fake antenna) perpendicular to us and we are facing the quad hence the real antenna is parallel and full broadcast from the wire's sides.

I will apply RCjameson's advice/mod as it will have a total of half wavelength but will have half that being at best possible broadcast angle. Should eliminate brownouts wthin 50meters and should increase total broadcast to 70-100meters on any remote...
 
That would depend on the power of the transmiter that is dedicated to the broadcast of command signals. So it cant be said to "all rtf transmitters" thats why i wanted to be more on the safe side of mentioning 70-100 meters.
 
B3Master said:
That would depend on the power of the transmiter that is dedicated to the broadcast of command signals. So it cant be said to "all rtf transmitters" thats why i wanted to be more on the safe side of mentioning 70-100 meters.
Click to expand...
I have transmitters with 4 AAA and some with 4 AA and 6 AA batteries ..they all give me 100m of range easily.

The SYMA X5 transmitter is more than capable of 70 to 100m as you are wanting with the above "range mod" at 1/4 wave length.

You're welcome to try whatever you want i just tend to stick to the K.I.S.S. method of things.
 
@ B3Master

According to member Patton he found that his X5's range was very dependent on his radio's batteries charge level. He claimed it didn't take much of a discharge to impact range.
 
Would be nice to see a lipo battery conversion mod in the x5 transmitter..im sure someone has done it .. the discharge curve on a lipo is far better than alkaline batteries or NiMh rechargeables.
 
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