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Body absorption

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Hello,

 

I am mainly doing documentaries / TV shows and I am satisfied with the range I get with my lectrosonics (SMQV and UM400a) as I place them most of the time in the talent's pocket or  I clip them on their belt or trousers. 

 

Now I am starting to do some short indie film so all my transmitters and my transmitter are put in URSA waist straps. And now it seems that i lost at least half of the range I would get by just placing them in pocket for exemple. I've read and heard about the fact that body does absorb RF but I did not expect it would be to that extent.

And what is more funny is that sometimes logic does not seem to apply, yesterday a skinny man would suck up the RF like crazy while a lady that suffers from obesity did not give as much trouble. Also old UM400a seems to be less affected by that issue.

 

How to fight against that without going the "Shark fin/ Distro" way? (I am only working with a bag)

 

Also I am wondering when people are using those new extra small transmitters that output 50mv instead of a 100mv, do they necessarily have to use amplified shark fin?

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If the antenna is actually touching the skin, you can lose much of your range.  I put 1/2 of an ursa foamie around the end of the antenna to keep it away from the skin.

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Try to put the transmitter on their ankle if you can. Thus less water between you and the talent. Also if you can anticipate which way talent will mostly face try to achieve as close to line of sight as possible. Make sure the mic cable doesn't touch the antenna, as that's a sure range killer in my experience.

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You can make an air gap insulator for the antenna using shrink tubing. Get a size (say, 3/8" unshrunk) that allows you to barely slip one end around the antenna down onto the connector, then shrink it at the connector so it stays in place. Then, cut the other end off just past the end of the antenna, then shrink that end and pinch it closed while hot, then trim it round. 

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Well blood and body tissue is roughly as dense as salt water which is denser than fresh water.

Thus......  (your conclusion here)_____________.

 

and then some people are just dense.

 

 

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49 minutes ago, S Harber said:

Well blood and body tissue is roughly as dense as salt water

Although this is correct, the density of a complete human body is less than salt water. (You knew that already, you float better on salt water.)
Hence, the human body contains air, so the solution (no, the answer to the question, not salt in water) is there.

Insert the antenna into the body for a nice air gap, while hiding it at the same time!

 

 

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Rigged in the trousers or skirt of a "large" person it's quite noticeable

Hence rig on the side of the garment

 

mike

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@karlw .. are you saying that a shrink tube encapsulating the antenna can help to prevent RF losses even if its touching the talent's skin ? Cool, never thought that such a thin amount of plastic could do some real difference.

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5 hours ago, Tales Manfrinato said:

@karlw .. are you saying that a shrink tube encapsulating the antenna can help to prevent RF losses even if its touching the talent's skin ? Cool, never thought that such a thin amount of plastic could do some real difference.

It's not the plastic it's the air.

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6 hours ago, Tales Manfrinato said:

@karlw .. are you saying that a shrink tube encapsulating the antenna can help to prevent RF losses even if its touching the talent's skin ? Cool, never thought that such a thin amount of plastic could do some real difference.

Shrink tubing that is only shrunk at the two ends with an air gap everywhere else. The more air gap, the better.

Best Regards,

Larry Fisher

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8 hours ago, Tales Manfrinato said:

@karlw .. are you saying that a shrink tube encapsulating the antenna can help to prevent RF losses even if its touching the talent's skin ? Cool, never thought that such a thin amount of plastic could do some real difference.

 

It's a "square of the distance" thing.

 

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I've had some success with sliding a hush lav onto the antenna. I cut/pull one hush lav in half and slide one down to the bottom of the antenna and leave one up at the top. 

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Been putting the hush lavs on the antennas as well. I just put one about the middle of the antenna.

Not sure why, but sometimes they come back from talent without the hush lavs.... 

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5 hours ago, Johnny Karlsson said:

Been putting the hush lavs on the antennas as well. I just put one about the middle of the antenna.

Not sure why, but sometimes they come back from talent without the hush lavs.... 

Topstick helps, put Hush on first though.

 

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Hush lavs work great for me as well— held in place on the antenna by topstick or super-mini rubber bands (which I buy in bulk and use for excess cable wrangling as well). Although in extreme situations, the hush can be its own form of absorption material and you get back a tiny sponge which is quite vile. 

 

The glamorous life of showbiz.  

 

Cheers,

Evan

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I have used Hush Lavs and make-up sponges. I currently use paper drinking straws, I got 100 of them in a dollar store. Have not done any with/without tests though. I assumed the paper straws are non-conductive.

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The Hush Lav's are an interesting and resourceful choice.

 

I've had good success (I think) with Tygon tubing. That's a flexible tubing generally available in any good hardware store. It's used in scientific research and also in aquariums and similar applications. The tubing has a relatively thick wall and, while flexible, has enough rigidity to hold shape. It can be cut with scissors or a pocket knife. Once slipped over an antenna, it can be secured with a small swatch of tape.

 

There are so many variables in radio use under "battle" conditions that it's hard to say how effective small adjustments like this are. My hunch, based on some experience, is that it helps.

 

David

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