kev308

I was wondering if anyone has tried "hiding the antenna on their tank? Is it possible? I would imagine you'll lose range, but what about function?
Thanks, Kevin

B.A.D.A.S.S.Force

Been done many times by hiding the antenna inside the tank, & when done right the range is usually pretty acceptable for most people.
Here are links to just a couple example threads on it.

Antenna Mod repost

Internal Antenna

This is a picture of pzrwest coil internal antenna & a variation of it


The picture below shows a PZ III antenna located in the back with the antenna wire winding back & forth between the plastic braces.




Edited to add a few pictures.

~ Craig ~

Captain Nemo12

Is there a reason for wrapping the wire in a coil shape (besides saving space)? Seems to me that you can just replace the antenna with a wire and line it along the inner side of the lower hull.

thecommander

There is no need a separate antenna for Tamiya tanks with RC hobby quality radios. These radio systems were mainly designed for airplanes that fly hundreds of feet overhead and may be 1/18 to 1/4 of a mile away. If we ever got that far from our tanks, we probably wouldn't be able to hear it or see what exactly it is doing. As a rule of thumb we are rarely more than 125 feet away. When I used to fly RC we always tested our planes radio range before flying for the day. Or else you risk crash damage or injuring someone. The cheap radios included with the tank (WSN/ Trumpeter, Heng Long/Mato) have very poor range. Just try to run a HL w/o the spring loaded antenna. The receiver in the tank needs a "external" antenna. The Tamiya RC Kubel also has a primitive radio Rx and need and antenna. I run only Futaba radios. None of my tanks have external antennas and most of my ant. wires from the Rx are coiled and bound next to the Rx.

Helpfull Hint: Do not go crazy mounting components like DMDs, MFs, Recievers and such in the hull with the double sided tape that Tamiya gives you. While it is very high quality it is VERY strong. It is very had to get DMDs and MFs apart or easily to relocate or temproarily remove them. In almost all Tamiya tanks (NOTE: this doesn't apply to the M26 Pershing) 3M Velcro is a much better choice. Test fit with the velcro before peeling of the glue shield tape. The velcro is a bit thicker. That is why the caramped M26 can't handle it. I can remove a DMD and MF from my tanks in under one minute for test, repairs or hull interior cleaning. I also like very neat and tidy wires. I call it "Wire Hygiene". I makes the tank look and run better. I hate a "birds nest" of wires. Clear scotch tape is very usefull. Cover your motor and keep the battery wires away from gearboxes. If the are pinched in the gears, a fire WILL occur.
Good Luck, Bob

Panther F

pzrwest had a thread on how to do that.

He was one of our most smartest and creative tankers here. Never attempted it as we Tamiya tankers use Hobby Grade Radios but I do coil my 'antenna' inside my tanks.














~ Jeff

Patski

actually with 2.4 Ghz you pratically dont need an outside antenna..I have a DX3C to run will all my rc cars and truck and never installed an antenna on those actually cant do much anyway with that short wire...

karel47

on my tanks of my Kampfgruppe Kesnika the antenna is soldered onto a metal antenna in scale , it works quite right, and the receiving of the signals coudn't be better ... a scale working antenna

B.A.D.A.S.S.Force

Pay attention Jeff, I had already posted pzrwest's thread link in the very second post ... I edited the post to add a few pictures now too


~ Craig ~

mcovalsk

If the coil is not properly designed (usually called antenna loading coil, which extend the physical large of the antenna ) has not other reason that save space. In fact is worst, the best is to make a square antenna ( or zigzag like pictures showing here) instead a small coil.

B.A.D.A.S.S.Force

Yes, you certainly can just position a straight or bent antenna along the inner side of the lower hull (like the picture I added of the winding PZ III antenna to the second post in this thread), or anywhere inside the tank, but each antenna type & shape used, as well as the positioning will affect the range, sometimes very drastically compared to the original HL antenna. So you can try any method & see which one provides enough range for you to be satisfied.

I have very little knowledge of the science behind antennas, but for seemingly such a simple thing, a piece of wire, there sure is a LOT of technical aspects going on for them to work effectively.

The optimal range should occur when both the sending & receiving antennas use the same polarization. Most people hold the transmitter more vertical to the ground, antenna pointing mostly upwards, so the straight antenna sends signals out which are vertically polarized. This is why the straight vertical to the ground HL stock whip antenna gets as much distance as it does, because it is also using vertical polarization as well as being the correct length for the frequency being used. Change the polarization of the antenna or its length, & the range can be greatly affected in negative ways.

Even though the coiled antenna wire is the same overall length as the straight antenna, the coiling does use up a lot less space than simple straight or bent antennas, & this will allow the antenna to be mounted inside the tank in a vertical position. It seems most people using these as inside coil antennas have had the best range when they are mounted vertically, rather than horizontally to the ground, inside their tanks.

So the internal antenna should have the same polarization to gain maximum efficiency for that antenna, which means you also want a vertical polarization. With the antenna bent or straight, but lying in a horizontal position to the ground inside the tank, you will lose the maximum range that antenna could provide because of the signal polarization. Coil antennas can work with both horizontal & vertical energy, & though not the best choice for bringing in a true vertically polarized signal, they should be better than any antenna that is only bringing in horizontal polarized signals, such as an inside horizontally place straight or bent antenna.

Maybe someone who knows this stuff better can correct me or confirm this, as I only knew about any of this after trying the coil antenna for myself in my own HL Panther G, as well as doing some internet information gathering, so I could be right, or I could be wrong on some or all of this, but the article I read when trying to figure this antenna stuff out, seemed to be pretty clear & factually written. Here is the article link => Antenna Polarization

~ Craig ~

B.A.D.A.S.S.Force

Well I did post the picture of the zig-zag antenna in a PZ III already in the second post in this thread. But I'm not sure I agree with the coil antenna being "the worst" unless you only meant if it was designed completely wrong itself, as many people have used them very successfully, getting almost as much range as the HL stock antennas.
It would be great if there were some verified tests showing results of the ranges people have gotten with their various types & positioning of their inside antennas.

I'd still like to hear input from any antenna expert on how the various internal antennas, if done correctly, should perform, & how important polarization of the signal is in regards to the type of antennas being used.

~ Craig ~

Ronan87

That. With 2.4 Ghz i get a LOT of range. AFAIK if it works on planes... subs... cars... trucks... it should be fine for tanks.

I can't beleive the price drops of 2.4 Ghz systems...

karel47

try my way to just solder him onto a steel antenna, its simple and effective ... i can run them at the end of our battlefield that over 110m far they react very well on the 40Mhz transmitters ... no need to wind them up keep it simple guy's

mcovalsk

Hi Craig I honestly think that the polarization matter is not applicable here. All the theory around that is based in the thinking you will radiate to a long distance and not to 4 or 5 meters. The shape and angle of the electromagnetic field is not crucial to so short distances.

I think that to make a coil with the large of the vertical antenna is not right from the design point of view, the equation to design a loading coil antenna is so complex that only people that works specifically on them could get a good result, but always talking about antennas that have to irradiate to long distances.

When you connect the output of the transmitter to a vertical antenna, the antenna shows a load to the transmitter, basically is the impedance. If you roll the antenna in a coil then the impedance will change definitively and to get the same load for a shorter antenna ( or no antenna) you must to calculate a coil that I’m sure will have a number of loops and diameter that nothing will have to be related to the large of the original vertical antenna that you want to replace. To think that the large must to be rolled around a cylinder of plastic is a simplification.

Did it work? Sure why not if you leave a loose cable inside will work also.

In my shermans I roll the antenna cable of the Futaba’s around the speaker box and works great, but doesn’t mean that I did something scientifically correct. I don’t need to look for links as I have my handbook for antenna designs and couplers but I know that’s not necessary for our models.

Of course if you are designing an antenna radio for TX/Rx for the RC Army airplanes then should to use all the math.

Hey! anyway I think that all this thread as well as others were very useful for me and others too.

B.A.D.A.S.S.Force

Are you talking about an inside hidden antenna, or keeping an outside antenna but placing it in the correct area on the tank where the antenna should be located, which for a Heng Long tank could be considered "hiding it" ?

If you are talking about an inside straight antenna, it would be great if you would post some pictures of your setup for everyone to see how you did it.

But just like some people experiencing great range with the inside coil antennas, while some have not had it, it goes the same with just using straight or bent antennas inside the tanks too. Also have to keep in mind that your 40MHz system performance most likely isn't going to be completely comparable to what an identical setup in a Heng Long tank using a 27MHz system might achieve.

~ Craig ~

B.A.D.A.S.S.Force

Maybe if you're battlefields are very small, & you always keep a constant short distance to your tank while controlling it, but for these already range limited 27MHz systems, I'm talking about 100 feet & more, well over a short 5 meters. And when we start talking of distances where some people might want to still maintain accurate control, like 200ft to 300ft, I think that certainly is a long distance, so having the proper polarization for the signals should make a big difference.

~ Craig ~

karel47

i go see for pics tomorrow its jut a correct steel antenna on the right spot were the receiver antenna is soldered onto , i did it the first time 13 years ago with my tamsherman , i never loose signal i goes way to far with this upgrade

kev308

Thanks for all the replies folks. I recently switched the tank to a taigen metal hull, so hopefully it'll work. Just curious though why does the wire have to be lacquered? wouldn't bare 14g wire work?
Thanks Kevin

heavyaslead

"Just curious though why does the wire have to be lacquered? wouldn't bare 14g wire work?"

Yes bare wire works, the wire is insulated to avoid shorts with other wires and metal components.

B.A.D.A.S.S.Force

Bare wire would work, but I think the main reason for using insulated wire is for safety ..... bare wire can create shorts if they contact other wires or connections & possibly do other damage, while the insulated wire would protect from that occurring.

~ Craig ~

Love To build

My Feedback: (30)

For radios antennas there are two factors. Impedance and length. The legnth is based upon frequency ( a full wave for 75Mhz is approx 74.9" and a 2.4Ghz is approx 2.4"). The length can be shortened to different sizes (75Mhz 1/2 wave is 37.45", 1/4 wave is 18.725" and so on). As you shorten the antenna you lose range. The impedance is the resistance of the antenna on the receiver. Keeping the wire the same length while wrapping around the tube keeps the impedance the same. For 2.4 Ghz radio the hidden antenna should not be an issue. For the older radios as long as the wire length is the same as the original design your replacing, the only thing you will be effecting on your tank receiver is distance and possible interference issues by wrapping a coil and placing inside the vehicle.

Pah co chu puk

That is to prevent the coil from shorting out with it's self. If the coils touch each other the antenna will act like it has a shorter wire and not work as well.

B.A.D.A.S.S.Force

Ahhh right, good call, actually forgot about that, it's very important for any coil antenna to work properly.

~ Craig ~

mcovalsk

Sorry but you are wrong antennas don't work in such way. If you wrap the wire around a tube you are making an inductance, then the impedance in the end will be absolutely different.
If you don't keep the vertical antenna in that position and leave a wire wrapen the impedance will change also.
There are two kind of antennas, dipoles 1/2 wave length and verticals 1/2 and 1/4. You can change the large of the antenna if you add a loading coil, then you can reduce the large of the dipoles and verticals.
In fact the verticals for 27Mhz should be around 2,75 mts and usually has 60 cm because the transmitter has a loading coil. If you remove the loading coil changing the output circuit and place a 2,75 mts and adapt the impedance you will have several db more of gain. Exactly the same works for a receiver.

Regarding to the antenna radiation pattern, 10 feet or 100 is the same, in fact most of the modelers have their radio’s antennas to 45° and there is not difference. The big problem with 27Mhz is the big interference and the fact that the radios are AM, citizen band is a very noise spectrum nowadays for AM.

YHR

[link=http://www.hobbyking.com/hobbyking/store/__9042__Hobby_King_2_4Ghz_6Ch_Tx_Rx_V2_Mode_2_.htm l]Answer to antenna problem[/link]