Mounting NMO antenna to aluminum truck cab?

[JohnDeere7920]

Hey everyone. Had a quick question about using one of the dreaded magnetic hockey puck NMO mounts in my 17 F350 which is of course aluminum. Obviously magnet won’t stick to the top of the cab so I’ve put some felt down with double sided tape to stick it there for my ground plane. 
 

question is the felt and double sided tape interfering with good grounding of the antenna? I really don’t want to screw anything through the top of my cab to secure the antenna mount to. Right now radios work in excess of 5 miles but if somehow fixing this would get me some more miles that would be great. I don’t have an SWR meter to check any of the specifics. Just bought MXT500 radios for farm use so communicate is kinda important at times. 
 

what’s everyone done to remedy the aluminum cab issue? Thanks I’m new here btw so bear with me as I learn these things. We’ve had business band radios for years but they have stopped working and now going another direction since we can’t fix and program our own radios. 
 

WSJV395

[amaff]

11 minutes ago, JohnDeere7920 said:

Hey everyone. Had a quick question about using one of the dreaded magnetic hockey puck NMO mounts in my 17 F350 which is of course aluminum. Obviously magnet won’t stick to the top of the cab so I’ve put some felt down with double sided tape to stick it there for my ground plane. 
 

question is the felt and double sided tape interfering with good grounding of the antenna? I really don’t want to screw anything through the top of my cab to secure the antenna mount to. Right now radios work in excess of 5 miles but if somehow fixing this would get me some more miles that would be great. I don’t have an SWR meter to check any of the specifics. Just bought MXT500 radios for farm use so communicate is kinda important at times. 
 

what’s everyone done to remedy the aluminum cab issue? Thanks I’m new here btw so bear with me as I learn these things. We’ve had business band radios for years but they have stopped working and now going another direction since we can’t fix and program our own radios. 
 

WSJV395

Remember that 'ground plane' isn't the same as electrically grounding something. You need a big piece of metal for the signal to bounce off of, you don't need the antenna to be electrically connected to the panel.

I don't know that I'd trust double sided tape on the exterior like that, but OEMs hang body panels off with that stuff now so what do I know 

[JohnDeere7920]

18 minutes ago, amaff said:

Remember that 'ground plane' isn't the same as electrically grounding something. You need a big piece of metal for the signal to bounce off of, you don't need the antenna to be electrically connected to the panel.

I don't know that I'd trust double sided tape on the exterior like that, but OEMs hang body panels off with that stuff now so what do I know 

Well that does make sense now that I think about it! I just assumed in order for it to bounce off and receive it would need to have a direct mechanical bond to the plane. So I should be good there. Now maybe I need to investigate the combine mounting because I’m not sure that the fiberglass rooftop that the NMO is mounted to there is a good option. I’m sure they have a ground plane under it but I would think a metal surface up top would be better

[SteveShannon]

1 minute ago, JohnDeere7920 said:

Well that does make sense now that I think about it! I just assumed in order for it to bounce off and receive it would need to have a direct mechanical bond to the plane. So I should be good there. Now maybe I need to investigate the combine mounting because I’m not sure that the fiberglass rooftop that the NMO is mounted to there is a good option. I’m sure they have a ground plane under it but I would think a metal surface up top would be better

There are adhesive back steel plates that can be bonded to a fiberglass surface to provide a decent ground plane. 

[WRUE951]

19 minutes ago, SteveShannon said:

There are adhesive back steel plates that can be bonded to a fiberglass surface to provide a decent ground plane. 

i'm thinking i would use this on the Ford Aluminium Cab.  Even on steel made bodies.  My Ram is steel tin and it aint' the asme steel tin cars used in the day, stuff now is  Very flimsy 

[WRXB215]

32 minutes ago, WRUE951 said:

stuff now is  Very flimsy 

Yep, just look at it wrong and it dents.