Car antenna installation advice

[RadioScannerSA]

Hi,

I have this antenna https://rcw.co.za/wp-content/uploads/2022/05/5.-ANT-M-504-Mobile-Antennas-Highband.pdf. I'm listening to 150mghz range.

I asked a car mechanic to install this antenna for me permanently in my car.
It is on a mag mount.

Before, I would stick the magnet on the side door and put the chord through the door into the car and the signal would be good.
But now, they put the magnet inside the car's hood so that the coil is inside the hood and just the straight part of the antenna is sticking out with a little bend so that it's straight up.

I'm finding that the signal is a lot worse now. Very noisy and I find I'm not picking up as much.

Am I correct in thinking this, or is it in my head?

Can anyone explain the mechanics of why the way they installed isn't ideal?
Is the fact that the coil is inside the hood affecting the signal?

Thanks!

 

[robertwbob]

id put it back like it was. never buy a mag mount then change it to solid mount n visa versa. you change its design. but thats my opinion.

 

[RadioScannerSA]

id put it back like it was. never buy a mag mount then change it to solid mount n visa versa. you change its design. but thats my opinion.

It's still a magmount, but they put it permanently in the hood.

 

[robertwbob]

It's still a magmount, but they put it permanently in the hood.

interesting

 

[FKimble]

If you want an antenna mounted correctly, go to a radio shop!

Frank

 

[bharvey2]

The coil at the base of the antenna IS part of the antenna so of course, placing it under the hood of your vehicle will adversely affect the antenna's performance as part of the antenna is now shielded or blocked from RF signals. When installed on a vehicle, the antenna normally performs best when mounted on the center of the roof, away from any obstructions whether on or off of the vehicle. Based on the cut sheet you supplied, I'm pretty sure that the antenna is an NMO mount, a very common and reliable mounting method. (However, now the antenna is attached to an NMO magnetic base. As has been noted above, go to shop familiar with installing two way radios. They should be very familiar with the proper installation of an NMO mount antenna.

 

[mmckenna]

I'd love to see photos of this install.

Honestly, what I'm imaging in my mind is pretty awful, and hoping it looks better than what my imagination is telling me.

So, yeah, @bharvey2 nailed it pretty well. The coil doesn't radiate/receive much, but it is part of the antenna. The engine compartment of your vehicle is a big bubbling soup cauldron of RF noise, heat and nastiness. Putting part of the antenna inside that is probably going to result in the radio picking up all kinds of noise that would normally be shielded by the hood.
Not sure how the antenna whip through the hood thing was done, but unless the hole is insulated and the no part of the radiating element is touching metal, you've effectively shorted out the antenna and that's going to make it work like dung.

The better way to do this is an NMO mount installed smack in the centre of your vehicle roof with a suitable VHF antenna with NMO base. And I'd not trust an auto mechanic to do the install. Get a radio shop to do it. They'll have the right tools to drill the 3/4 inch hole and they'll be able to properly install the connector on the end of the cable.

 

[robertwbob]

I'd love to see photos of this install.

Honestly, what I'm imaging in my mind is pretty awful, and hoping it looks better than what my imagination is telling me.

So, yeah, @bharvey2 nailed it pretty well. The coil doesn't radiate/receive much, but it is part of the antenna. The engine compartment of your vehicle is a big bubbling soup cauldron of RF noise, heat and nastiness. Putting part of the antenna inside that is probably going to result in the radio picking up all kinds of noise that would normally be shielded by the hood.
Not sure how the antenna whip through the hood thing was done, but unless the hole is insulated and the no part of the radiating element is touching metal, you've effectively shorted out the antenna and that's going to make it work like dung.

The better way to do this is an NMO mount installed smack in the centre of your vehicle roof with a suitable VHF antenna with NMO base. And I'd not trust an auto mechanic to do the install. Get a radio shop to do it. They'll have the right tools to drill the 3/4 inch hole and they'll be able to properly install the connector on the end of the cable.

im like you,like to see the install. he would been better off leaving it as it was made.

 

[bharvey2]

I'd love to see photos of this install.

Honestly, what I'm imaging in my mind is pretty awful, and hoping it looks better than what my imagination is telling me.

im like you,like to see the install. he would been better off leaving it as it was made.

I don't know. This kind of reminds me of that '80s movie "Stand By Me" with the kids wanting to go see a dead body.

 

[MiCon]

I'm no expert on antenna installations, but I'm assuming that when you say it's mounted on the 'hood', you mean the engine hood. Even my limited knowledge says that's a no-no. It was bad enough decades ago with the spark plug staccato and the alternator whine, but with todays engines loaded with electronics, the engine RF interference is something you want to stay away from.

It's obvious that you trust your mechanic, but a radio installer would have known better. I, too, would like to see this install, and I'd be interested in the conversation that led to it. Just curious what you told the mechanic, and what he had to say about where he'd nstall this antenna.

 

[WA0CBW]

I would like to see a picture as well. This would be the classic picture of how to NOT install a magnet mount antenna (or any antenna). I'm also wondering about you installing the magnet to the side door. That also conjures up pictures of how to not install an antenna.
Bill

 

[robertwbob]

I would like to see a picture as well. This would be the classic picture of how to NOT install a magnet mount antenna (or any antenna). I'm also wondering about you installing the magnet to the side door. That also conjures up pictures of how to not install an antenna.
Bill

i think we wont be seeing any mount pictures by now. was sure ready to view them.