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Old Jul 12, 2009, 06:42 AM
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Joined Nov 2008
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Question
RX aerial length

Can anyone tell me what effect the length of aerial has on 36MHz FM.
I recently broke the aerial wire of a little 4ch Rx, I think it was about 1 meter in length. Do I make the new wire the same length or is there an advantage in making it a bit longer.

Thanks George
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Old Jul 12, 2009, 08:03 AM
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Joined Jun 2009
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i'm no expert but i'm pretty sure that's a case of a new receiver as I think the aerial length is an exact science to pick up the transmitter waves properly.

it's length i think is exactly measured to a proportion of the wavelength of the transmitted frequency.

sorry i can't be of more help. try asking your LHS, although I guess they're just going to try and sell you another Rx.
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Old Jul 12, 2009, 08:05 AM
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Mr. RC Cam has done some very good investigative work on what happens when you change the length of your antenna, usually not a good result for either lengthening or shortening. I do not have his web site listed but you can probably Google it or maybe some other reader can provide it. You are correct in that, for most brands, the standard length of the receiver antenna is 1 meter. In general, any length from 39 to 41 inches will work equally well.
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Old Jul 12, 2009, 09:15 AM
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Canada, ON, Ottawa
Joined Feb 2006
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Making the receiver longer may reduce range. Stay with the standard 1m (39-40").
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Old Jul 12, 2009, 12:36 PM
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Here's the RC Cam antenna article-well worth reading.
http://www.rc-cam.com/ant_exp.htm
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Old Jul 12, 2009, 05:49 PM
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Colonial Heights, Virginia, USA
Joined Mar 2001
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Hi GeorgeM .... here in USA, not familar with 36mhz receivers but you should replace Rx antenna with original length....i always range test ( and make written notes for later comparisons) my new or normal working Rx's (waiting until problems develope is too late) with all my Tx's (using std range test proceedure) to detect any significant range problems before getting airborne...whatever Rx length you finally use should range test normal... good luck kw
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Old Jul 13, 2009, 03:45 AM
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Receiver & Tx Antenna - Original length Hitec, Futaba, GWS, JR & Others

Quote:
Originally Posted by GeorgeM
Can anyone tell me what effect the length of aerial has on 36MHz FM.
I recently broke the aerial wire of a little 4ch Rx, I think it was about 1 meter in length.
Do I make the new wire the same length or is there an advantage in making it a bit longer. Thanks George
Brand and model number not mentioned.
Repair with multi strand (45g) flexible wire for small "lite" receivers and down to 22 gauge for the larger solid case receivers.
AOK to rejoin with solder (do not use acid flux) or additional wire to make up to correct length
and cover joint with heatshrink tube .
Receivers are base loaded so original length is best but an inch shorter or longer does not impact significantly.
. Receiver - Antenna - Does Length Really Matter?
As insulation on older antenna may have got brittle or cracked, preferable to visit your LHS
and select an original replacement Receiver Antenna, part number and lengths are as follows:

Castle Creations (Berg aka Hyperion) receivers:
Berg Antenna FAQ
. MicroStamp 4 = Antenna wire length: 38" (965mm)
. DSP6-FS & 7P = 39" (1000mm)

Corona:
All are 41 inches

FMA
Quantum = 39.5" (1003mm)

Futaba Receivers
Original use "24 gauge multi-stranded wire with PVC coating. A slightly-larger wire gauge won't hurt.
Length is absolutely critical" by Bill Baxter, Manager Hobby Services/Futaba Service/North America,
This as Futaba receivers have an input inductor that matches the original length of wire antenna, as listed below,
to the respective receiver RF circuits.

Futaba receivers have various lengths ex factory, replacement antenna (aerial) part numbers & lengths
(tinned solder end to tip, not case to tip)as follows:
500mm as parts #0131 AM/FM27, #0133 AM/FM29, #0134 AM/FM40 for Futaba 2ch RX = short range use for cars/boats
500 mm (19.6") for R303FHS, R113F & R113iP RX all frequencies,
485 mm (19") for R152JE all frequencies,
495 mm (19.4") for R203HF all frequencies
700 mm (27.4") for R114F all frequencies
985 mm (38.8") for R148DF, R148DP, R149DP,
1000mm (39.4") as parts #0135 AM27 R102JE (long range) #0136 FM35, #0140 AM/FM29 (4ch+),
#0141 AM/FM40 (4ch+), #0142 FM35 = R137/9), FM 72 MHz R127DF, R138DP,
1100mm (43.3") as part #0146 for FM40 = 118G, 137GP, 139GP
1200mm (47.24") for FM40 = R137/9.
Futaba 2.4Ghz ex factory
A16101 = R603 & R604FS- (silver head) length 210mm
A15801 = R606, R607, R608, R614, R617FS (gold head) length 210mm
Futaba 2.4Ghz Replacement Antenna as sold in USA, Code:
#HSP79493 (not a Futaba factory number) for R617 & R606FS length is 150mm

Futaba Transmitters: FF6 995mm FF7 1200mm

GWS:
GWS FAQ
GW/R4PII, R4PII/H, R4PII/T, R6NII, R6NII/H 500 mm (20"). 1000 mm (39.5") all others.

Hitec
Receivers have an input inductor that matches the original length, as below, of
wire antenna to the respective receiver RF circuits. Use 24 to 28 gauge.
Hitec original replacement antenna (aerial) part numbers and actual lengths
(tinned solder end to tip, not case to tip) are as follows:
#58011 which measures 106 CM (= 41.75 inches) from pre-tinned tip to end.
(105 CM quoted some sites is only the length from outside of case)
"A black Antenna (aerial) wire & doubler used for all Hitec RCD airborne RX, for all frequencies
27MHz, 29 MHz, 35 MHz, 40 MHz, 41 MHz, 72 MHz, 75 MHz"
Exceptions being the HFS-05MS antenna which is shorter at 60 CM (23 5/8 inches)
and the discontinued original red cased 4ch Feather as follows:
#54001 Green for use with red cased Feather 4CH receiver
[lighter wire than #58011 but still 106 cm (41.75 inches)]
#54002 Red Antenna (aerial) Wire, with doubler, for Regular Surface Receivers which measures 61 CM (24 inches)
as now fitted to current 27 MHz, 29 MHz, 40MHz & 75 MHz surface receivers with the exception of
HIS-03MK IPD receiver which has an antenna length of only 43 cm (17 inches).
Replacement 2.4GHz Antenna: note comment on photo below
. Hitec 2.4Ghz BODA Antenna search " 2.4RXANTENNA ".
otherwise international 700892 but first digit may vary
. Hitec 2.4Ghz TX(Spectra) Antenna (without base) search " 2.4TXANTENNA ".

. OPTIMA Receivers for Indoor & Parkflyers & Alternate Antenna.

JR =
JR use 1000 mm for all their known RX irrespective of frequency.
i.e: same length for 35 MHz, 36 MHz, 40 Mhz, 41 MHZ & 72 MHz etc.,
One exception being RS300 27 Mhz & 75 Mhz Receiver antenna = 51cm (20").
(JR receivers have an input inductor that matches the antenna wire length quoted to the RF circuits).

Multiplex
RX-9 Synth - 87cm from tip to the case.
Mini DS - 87cm from tip to the case.
(MPX Service Dept notes overall length board to tip min 35" max 39")

2.4GHz Receiver Antenna - General Information:
The standard length for the stripped portion of 2.4 coax antennas is 31mm.
When the antenna is plain wire and directly connected to the board, the length may vary a bit
as a result of loading in the circuit.
A smaller 2.4GHz antenna can be used, as detailed links below, but for Optima transceivers return telemetry
distance is compromised, as supplied unit also optimises transmission from RX.
Optima 2.4GHz Antenna - Pictures of Head and Socket.
Lightweight modification 01 - How to change antenna - pictorial.
Lightweight modification 02 - How to change antenna using a Digi-Key Part #: A36229-ND
(Leave something like a 6" antenna and then strip the outer sheath off about 1" of the tip.)

2.4GHz antenna - Alternate:
F1431 - Robbe RX aerial, 2.4 GHz 150 mm (R606-6014)
2.4G Receiver Antenna 150mm
Optima BODA antenna DIY Shorten or Replace and Alternatives.
25Nov12: attached two .lpg of 2.4 GHz antenna showing the connectors.
These can be used as replacements on most 2.4Ghz receivers including Hitec
but be aware that the connections are generally rated for a maximum of 5 connect/disconnect.

Transmitter Antenna Lengths:
(All brands use standard lengths for each model irrespective of frequency)

Hitec
58001 2N/3SS/Focus 2SS & 3SS 960 mm
58004 Focus/Flash/Lynx 1100 mm
58005 Optic 6, Laser 4&6, Eclipse 7, Prism 7, Aurora 72mhz 1200 mm
58006 Lynx 3D 740 mm
58007 Aggressor & Ranger 2N series 700mm

Futaba
FF7 (FP-T7UAP) 1100 mm
FF6 (T6X) 960 mm
Attack 4 T4NBL 860 mm
Challenger FP-T4N 1020 mm
Magnum SportbFP-T2P 960 mm
T2PHKA 27/29 MHz 830 mm
FP-2vR (Attack SR) 950 mm
2DR, 2ER 950 mm

JR
X-347, X-3810, X-8103 1155 mm
Beat 2ch 27/29/35/40/72MHz 870 mm

MacGregor
Radio Control 27/29 MHz 1200 mm

Radio Control Specialists
Guidance System 27/29Mhz 1165 mm

Sanwa (Airtronics)
Dash 2ch 27/29/35/40/72MHz 920 mm

UHF systems
UHF systems (433MHz). Custom monopole antennas tuned for 433MHz.

More information under sub sections
"Antenna - Rubber Duckie, Micro & Whip Flywire - replace long aerials with loaded base antenna" and
"Receiver - FAQ, guides and aids to best reception" at
Alan's Hobby, Model & RC FAQ Web Links

Alan Tong

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Last edited by A.T.; May 06, 2014 at 06:47 PM. Reason: Add more Tx.
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Old Jul 13, 2009, 04:57 AM
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Joined Nov 2008
213 Posts
Thanks for all the replys. The RX is one of those horrible little Corona 4ch synth recievers.
Today after reading the info in the reply from "Flydiver". I tried an aerial length of 52" just as an experiment and it definately gave a better range test. About 12 to 15 ft extra with aerial down on my JR 652. In the air I couldn't notice any difference. It still gave me a little twitch when it flew over a certain stand of trees that has always done.
I'll probably cut it back to the original length just so there isn't so much hanging out the back of the little Mugi Evo.
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