RC Model Reviews

Hi,

I wonder if all the 2.4Ghz antenna are similar and interchangeable? Can one use WIFI antenna in our Turnigy 9CH ver 2 TX? For example if my antenna broke, can I buy one of these WIFI router antenna and, with some modifications, fitted it in and have the same RF performance as the original antenna?

Another question is the "sleeve dipole" antenna, why is the one on the Turnigy 8CH Ver2 RX so big in diameter when the one fitted to the Traxxas TQ RX is so slim in comparison (1.5mm), are they not electrically similar? Can I desolder the Traxxas one and fit it to my Turnigy 8CH RX and have the same RF performance? This is because I wanted to fit a Turnigy 8CH into my Traxxas Summit truck but the antenna is too big, the Traxxas one is so slim it would slide into a small standard antenna tube.

Most 2.4GHz transmitter antennas are pretty compatible. They're all designed to present a 50 ohm load to the transmitter circuitry.

However, you may find that there's a difference in the connector -- some RC systems use an SMA connector, others use a RPSMA (reverse-polarized -- where the pin is in the other part of the mating connectors).

An antenna designed only for reception may not be a good transmitter antenna because it may not be the 50 ohms required for best performance. Receiver antennas are usually designed to be light and compact, transmitter antennas are designed to be a good match to the transmitter.

I have a final question on antenna, would appreciate your answer on this. Does the diameter of the "sleeve" in the sleeve dipole antenna matter? That is the circumference of the sleeve, I know that the length must be equal to the tip to make a dipole, but I see that most sleeve dipole use a sleeve that is fairly much bigger than the coax cable itself and even have a plastic element to centre it at the bottom, most 2.4Ghz antenna when stripped will show this bulbous tube. However in a Traxxas RX this sleeve is shrunk in diameter to fit right over the tiny coax so that the whole dipole is not much thicker than the coax itself, no doubt it was done so that the antenna could slip into the antenna tube mounted on the model but the question is whether having such a small tube sleeve affect the performance of the antenna at all? If not why does all other manufacturer uses a bigger copper/tin tube as the second pole? What is the trade off for using such small sleeve?

The sleeve diameter does make a small difference but it would be possible to make a sleeved dipole by simply folding the outer coax screen back over the cable if you really wanted to. However, for best results the sleeve (and the protruding inner) should be kept as straight and "in-line" as possible -- which is one of the reason manufacturers tend to use a metal sleeve.

Thanks for your reply, I take it that having a small tight fitting metal sleeve does impact slightly upon the performance of the antenna but that Traxxas think it is a worthwhile trade-off to get the antenna to fit better.