Antenna/Skin Insulators

[Paul F]

The Viviana Antenna Saver had me wondering what it does, since no data is published about performance; not that I blame them. There are too many variables to say what results one will get.

 

I had some silicone tubing that was about the right size and I gave it a try. The tubing I have does not keep the antenna away as far as the Viviana item. It provided at least an 8db signal improvement. I did not notice any improvement moving the antenna further away.

 

I experimented with the antenna distance from the skin. The signal starts to noticeably attenuate at about 3/16" from the body. So I think Viviana got it right with their product.

 

Thumbs up for this product.

[The Documentary Sound Guy]

Thanks for the test!  I've been skeptical, maybe I'll do some experimentation now.

 

[Philip Perkins]

Isn't this thing a challenge re: tight wardrobe?

[Johnny Karlsson]

I’ve been using a hush-lav held in place center antenna by a piece of top stick for years, and recently started using the aquarium tubing recommended by Karl W.

 

IDK what the exact dB difference might be but I do believe it helps either way. Certainly doesn’t hurt. The Viviana stuff is probably great, but the aquarium tubes are like 5 bucks for 20 ft. 

One thing I noticed is that I think the aquarium tubes has some kind of chemical reaction with topstick. So I’m now trying to figure out a way to get them to stay on the antenna with some other method.

[borjam]

7 hours ago, Johnny Karlsson said:

One thing I noticed is that I think the aquarium tubes has some kind of chemical reaction with topstick. So I’m now trying to figure out a way to get them to stay on the antenna with some other method.

What kind of aquarium tubing?

Turns our I had a marine aquarium years ago. And the classical PVC "green" tubing sold by Eheim and other brands did indeed react with salt water. It got stiff with time. As sweat is salt water with mode stuff I would avoid them just in case someone developed an allergy.

 

There are slightly more expensive hoses made of silicone. I would recommend these. It is also softer to the touch, while the PVC version is more stiff.

 

[Johnny Karlsson]

They are silicone. The reaction I mentioned is that the glue of topstick seems to “melt” and become messy.

 

here’s the link to it:

 

https://a.co/d/5olIC4P

 

[Pocketsizesound]

Hello everybody. I have been wondering about this product and technique. The Viviana product has a rather large effective diameter, which will make talent less comfortable, so I would use only if I must. But I do not understand the principle behind the spacer - the antenna is insulated, so the mere fact of contact with sweat/skin means absolutely nothing. For physical spacing, separated 5-10mm from the body, the RF transmission still needs to go through the body. The only thing that comes to my mind is that the effective transmitting area of the antenna that does not transmit directly through the body somewhat increases. But that increase can not be large. I would assume the position of the receiver will greatly effect results in the practical tests. Anyway, any radio engineers in the crowd? Thank you. 

[Paul F]

LarryF, the RF expert from Lectrosonics explains it this way. Humans are essentially a bag of water. RF doesn't like a bag of water. I don't have the scientific explanation, but getting the antenna physically away from the body helps transmission. It's not really acting as an insulator. It's just getting the antenna away from the bag of water improves transmission.

 

As noted in my tests, I saw a significant increase in signal level just a few millimeters from the body. Anything will work (well, not metal), as long as it distances the antenna from the body.

 

Sound people have  been using various items to do the same thing for quite some time. Like I used to use Ursa foamies. Viviana just came up with a specific commercial solution for the problem.

 

Larry is a treasure trove of information. Maybe he can add the science behind it.

[Conor]

On 1/20/2025 at 9:36 AM, Pocketsizesound said:

Hello everybody. I have been wondering about this product and technique. The Viviana product has a rather large effective diameter, which will make talent less comfortable, so I would use only if I must. But I do not understand the principle behind the spacer - the antenna is insulated, so the mere fact of contact with sweat/skin means absolutely nothing. For physical spacing, separated 5-10mm from the body, the RF transmission still needs to go through the body. The only thing that comes to my mind is that the effective transmitting area of the antenna that does not transmit directly through the body somewhat increases. But that increase can not be large. I would assume the position of the receiver will greatly effect results in the practical tests. Anyway, any radio engineers in the crowd? Thank you. 

It's not just about the propagation of the signal but also the effectiveness of the antenna. I did a test here with a NanoVNA where you can see how dramatically direct contact to the skin lowers the SWR (effectiveness) of a whip antenna

 

[borjam]

1 hour ago, Conor said:

It's not just about the propagation of the signal but also the effectiveness of the antenna. I did a test here with a NanoVNA where you can see how dramatically direct contact to the skin lowers the SWR (effectiveness) of a whip antenna

 

 

Exactly. It detunes the antenna. Although it seems silly that a thin dielectric can make a difference (a thin plastic tubing for instance) there is a capacitance between the skin and the antenna.

Even an apparently insignificant 1 mm thick dielectric (silicone tubing?) will change that capacitance dramatically. At least that the explanation I imagine.

 

And if the antenna is detuned it can have nasty effects on the transmitter, even causing signal distortion (plus the energy loss). I imagine (no proof!) that one of the key differences between top notch professional wireless systems and  more affordable alternatives is how tolerant of that impedance mismatch is the transmitter. Another difference of course is how much out of band interference can be tolerated by the receiver.

[Viviana Sound Solutions]

Thank you for creating this group.
As you rightly mentioned, the Viviana Sound Solutions “RF Saver” is designed to prevent antenna detuning every time it comes into contact with the body.

 

What is Antenna Detuning?
An antenna is designed to pick up and send specific radio frequencies (RF), like a finely tuned musical instrument playing the right note.
Detuning happens when something causes the antenna to stop being perfectly "in tune" with those frequencies.

 

What Causes Detuning?
* Physical objects: A hand, body, or metal object near the antenna can mess with its tuning.
* Bad placement: If the antenna is bent, too close to walls, or improperly set up.
* Frequency mismatch: If the signal you're sending/receiving doesn’t match the antenna's ideal frequency

 

Effects of Detuning on RF Signal
* Weak Signal: The antenna becomes less efficient, so it picks up or sends less of the signal. It’s like trying to talk through a clogged microphone.
* Interference: You might start picking up unwanted noise or other signals.
* Dropouts: The signal might cut in and out, leading to unreliable performance.

 

A Simple Example
Think of it like this: If your radio isn’t tuned to the exact frequency of your favorite station, the sound becomes fuzzy or disappears entirely. The same happens with an antenna and RF signals when it's detuned.

 

I personally tested the RF Saver in a professional labs before introducing it to the market to ensure its functionality through machine analysis.

 

Why it works:
It's not just a soft rubber tube. Inside the RF Saver, there’s a rail that keeps the antenna perfectly centered and surrounded by air, ensuring maximum performance (picture attached).

The material used does not absorb RF signals.
I used to use foam myself, but foam absorbs sweat, and sweat contains salt, which makes it conductive.

 

RF Saver dimensions:
It is slightly smaller than a Hush Lav and is injection-molded to guarantee maximum quality. It took us six months to find the right rubber that doesn’t absorb RF signals, so be careful when using silicone tubes or untested materials.

 

A solution for tight-fitting clothing is to hide the tx with the antenna positioned vertically downward instead of the classic position with the antenna pointing upward.

The antenna's polarization doesn't change, so you'll still have the same RF signal performance.

 

Be careful not to position the transmitter antenna horizontally if the receiver antennas are vertical, as this would create a polarization mismatch, leading to RF signal issues.

 

I hope this information makes the product and the concept of detuning more clearer.

 

Thank you very much for using Viviana Sound Solutions products.

 

If you have other questions I will be more then happy to reply.
See you soon!

 

Ciao

Turi

[Pocketsizesound]

12 hours ago, Conor said:

Have you tried to compare results between touching the antenna (in reality - the insulator) and just placing your hand close to the antenna? 

 

Thanks. 

 

 

Finally, the logical question would be - if spacing improves the signal dramatically, why none of the manufacturers in the last 70 years offered a bodypack antenna with a thick insulator? 

It could very well be that the reason for improvement is the fact that with the spacer the antenna bends less. 

 

 

[Jim Feeley]

On 1/19/2025 at 11:36 PM, Pocketsizesound said:

The Viviana product has a rather large effective diameter, which will make talent less comfortable,

 

That hasn't been my experience. I guess it could be, but it's a useful item. 

[Paul F]

1 hour ago, Pocketsizesound said:

 

Finally, the logical question would be - if spacing improves the signal dramatically, why none of the manufacturers in the last 70 years offered a bodypack antenna with a thick insulator? 

 

 

 

 

AHH! AHH!  It was not obvious! I claim the patent! I'm calling my lawyer now!

 

I have to say, that's not a bad question.

[Conor]

On 1/21/2025 at 11:12 PM, Pocketsizesound said:

 

Finally, the logical question would be - if spacing improves the signal dramatically, why none of the manufacturers in the last 70 years offered a bodypack antenna with a thick insulator? 

It could very well be that the reason for improvement is the fact that with the spacer the antenna bends less. 

 

 

My guess - such a product would have a dramatically increased cost over the standard whips (which are already effective enough and relatively cheap/easy to produce), for a (in practice) small increase in performance. I don't think that this practice of having a spacer improves signal so dramatically as to be an absolute necessity, plenty of mixers are getting along just fine without them. Yes it is an improvement, but not a cure-all. Next to a sack of water, most of this stuff is out the window anyway.

[The Documentary Sound Guy]

My guess is they would get complaints about solid antenna being uncomfortable and hard to hide.  It's not cost — the WiFi antennae that ship with routers are routinely sheathed in plastic, and cost less than $10 retail.  Made in bulk, they would add negligibly to the cost.