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What's this on the GPS antenna lead?

Bruce Coates
 

Hi Kip

Yup.  The idea of it providing a method for coupling to a ground plane certainly seems to be the most plausible purpose.

73, Bruce

------ Original message------
From: AE5IB (Kip)
Date: Fri, Jul 13, 2018 7:56 AM
To: GPSL;
Cc:
Subject:Re: [GPSL] What's this on the GPS antenna lead?

I can not put my hands on it right now, but a GPS antenna specification i read last year, recommended the antenna be mounted on a minimum of  40mm x 40mm ground plane to get maximum GPS sensitivity! . 

My guess is that they are facilitating that requirement, to make the antenna system easier to ground to a metal plate. 

Kip

On Thu, Jul 12, 2018 at 10:45 PM Bruce Coates <bruce.coates@...> wrote:
Right. Missed that part. Yes, the entire "back" side of the mesh is covered with adhesive. I think that's what holds it to the shield as there no evidence of any soldering or other electrical connection. 

-------- Original message --------
From: "Hank Riley via Groups.Io" yahoo.com@groups.io>
Date: 7/12/18 8:21 PM (GMT-06:00)
To: GPSL@groups.io
Subject: Re: [GPSL] W! hat's this on the GPS antenna lead?

The decoupling idea did occur to me, but I did kind of slide over your wording concerning the coax shield.

A few more clue requests:

By "connected," do you really mean connected galvanically to the shield?   Or just folded around the coax tightly?  Can't tell by the photo for sure.  One picture I found looks as if there might be a sliver of shield exposed on the end of the mesh closest to the antenna.  If connected, please describe how that's done (one or two places; by solder?). 

Does the adhesive cover the central area of the mesh at all?

My thought was attaching the mesh to the coax was simply for product packaging purposes and was intended to be only temporary until applied to the antenna. 

Maybe the mesh does both functions.  I don't think the entire mesh area is needed for decoupling.

__________________________________________________________

Hi Hank

Interesting. I was also wondering about it being some attempt at common mode decoupling, like a 1/4 wave stub.

73, Bruce

AE5IB (Kip)
 

I can not put my hands on it right now, but a GPS antenna specification i read last year, recommended the antenna be mounted on a minimum of  40mm x 40mm ground plane to get maximum GPS sensitivity. 

My guess is that they are facilitating that requirement, to make the antenna system easier to ground to a metal plate. 

Kip


On Thu, Jul 12, 2018 at 10:45 PM Bruce Coates <bruce.coates@...> wrote:
Right. Missed that part. Yes, the entire "back" side of the mesh is covered with adhesive. I think that's what holds it to the shield as there no evidence of any soldering or other electrical connection. 

-------- Original message --------
From: "Hank Riley via Groups.Io" <n1ltv=yahoo.com@groups.io>
Date: 7/12/18 8:21 PM (GMT-06:00)
To: GPSL@groups.io
Subject: Re: [GPSL] What's this on the GPS antenna lead?

The decoupling idea did occur to me, but I did kind of slide over your wording concerning the coax shield.

A few more clue requests:

By "connected," do you really mean connected galvanically to the shield?   Or just folded around the coax tightly?  Can't tell by the photo for sure.  One picture I found looks as if there might be a sliver of shield exposed on the end of the mesh closest to the antenna.  If connected, please describe how that's done (one or two places; by solder?). 

Does the adhesive cover the central area of the mesh at all?

My thought was attaching the mesh to the coax was simply for product packaging purposes and was intended to be only temporary until applied to the antenna. 

Maybe the mesh does both functions.  I don't think the entire mesh area is needed for decoupling.

__________________________________________________________

Hi Hank

Interesting. I was also wondering about it being some attempt at common mode decoupling, like a 1/4 wave stub.

73, Bruce

Bruce Coates
 

Right. Missed that part. Yes, the entire "back" side of the mesh is covered with adhesive. I think that's what holds it to the shield as there no evidence of any soldering or other electrical connection. 


-------- Original message --------
From: "Hank Riley via Groups.Io" <n1ltv@...>
Date: 7/12/18 8:21 PM (GMT-06:00)
To: GPSL@groups.io
Subject: Re: [GPSL] What's this on the GPS antenna lead?

The decoupling idea did occur to me, but I did kind of slide over your wording concerning the coax shield.

A few more clue requests:

By "connected," do you really mean connected galvanically to the shield?   Or just folded around the coax tightly?  Can't tell by the photo for sure.  One picture I found looks as if there might be a sliver of shield exposed on the end of the mesh closest to the antenna.  If connected, please describe how that's done (one or two places; by solder?). 

Does the adhesive cover the central area of the mesh at all?

My thought was attaching the mesh to the coax was simply for product packaging purposes and was intended to be only temporary until applied to the antenna. 

Maybe the mesh does both functions.  I don't think the entire mesh area is needed for decoupling.

__________________________________________________________

Hi Hank

Interesting. I was also wondering about it being some attempt at common mode decoupling, like a 1/4 wave stub.

73, Bruce

Bruce Coates
 

Yes, it's definitely electrically connected to the coax braid.  They're stripped the outer insulation for the entire width of the mesh and wrapped the mesh tab around it.  Oddly, either the adhesive is conductive or there's enough metal fibres that pass through the adhesive to conduct.

Here's a shot under a microscope.  (I love my microscope!)

73, Bruce

On 2018-07-12 8:21 PM, Hank Riley via Groups.Io wrote:
The decoupling idea did occur to me, but I did kind of slide over your wording concerning the coax shield.

A few more clue requests:

By "connected," do you really mean connected galvanically to the shield?   Or just folded around the coax tightly?  Can't tell by the photo for sure.  One picture I found looks as if there might be a sliver of shield exposed on the end of the mesh closest to the antenna.  If connected, please describe how that's done (one or two places; by solder?). 

Does the adhesive cover the central area of the mesh at all?

My thought was attaching the mesh to the coax was simply for product packaging purposes and was intended to be only temporary until applied to the antenna. 

Maybe the mesh does both functions.  I don't think the entire mesh area is needed for decoupling.

__________________________________________________________

Hi Hank

Interesting. I was also wondering about it being some attempt at common mode decoupling, like a 1/4 wave stub.

73, Bruce


Hank Riley
 

The decoupling idea did occur to me, but I did kind of slide over your wording concerning the coax shield.

A few more clue requests:

By "connected," do you really mean connected galvanically to the shield?   Or just folded around the coax tightly?  Can't tell by the photo for sure.  One picture I found looks as if there might be a sliver of shield exposed on the end of the mesh closest to the antenna.  If connected, please describe how that's done (one or two places; by solder?). 

Does the adhesive cover the central area of the mesh at all?

My thought was attaching the mesh to the coax was simply for product packaging purposes and was intended to be only temporary until applied to the antenna. 

Maybe the mesh does both functions.  I don't think the entire mesh area is needed for decoupling.

__________________________________________________________

Hi Hank

Interesting. I was also wondering about it being some attempt at common mode decoupling, like a 1/4 wave stub.

73, Bruce

Bruce Coates
 

Hi Hank

Interesting. I was also wondering about it being some attempt at common mode decoupling, like a 1/4 wave stub.

73, Bruce


-------- Original message --------
From: "Hank Riley via Groups.Io" <n1ltv@...>
Date: 7/12/18 6:29 PM (GMT-06:00)
To: GPSL@groups.io
Subject: Re: [GPSL] What's this on the GPS antenna lead?

Bruce,

I'm pretty sure that's a ground plane intended to be affixed to the underside of the supplied antenna to improve its performance.  One of the clues is the presence of the adhesive; another is the size of the mesh.  A nice touch for that to be included in the package.

Hope this solves the "Mystery of the Thing."

Hank
___________________________________

My module has an adhesive "thing" on the feedline about half way down. This "thing" is fine metal mesh and is connected to the shield of the feedline.  It seems to be common on the tiny ceramic antennas on eBay but many also don't have it. 

Hank Riley
 

Bruce,

I'm pretty sure that's a ground plane intended to be affixed to the underside of the supplied antenna to improve its performance.  One of the clues is the presence of the adhesive; another is the size of the mesh.  A nice touch for that to be included in the package.

Hope this solves the "Mystery of the Thing."

Hank
___________________________________

My module has an adhesive "thing" on the feedline about half way down. This "thing" is fine metal mesh and is connected to the shield of the feedline.  It seems to be common on the tiny ceramic antennas on eBay but many also don't have it. 

Bruce Coates
 

Hi

I'm building a tracker using a Ublox Neo 6m module from eBay (of course).  My module has an adhesive "thing" on the feedline about half way down. This "thing" is fine metal mesh and is connected to the shield of the feedline.  It seems to be common on the tiny ceramic antennas on eBay but many also don't have it. 

Any ideas?

Thanks

Bruce - VE5BNC