NGP mobile antenna vs regular mobile antenna

[FlyBoy50]

Spent some time today thinking about NGP antennas in the mobile environment and seeing I have no experience with them I cant help but wonder if they are really any good, or are they basically ( Something is better than Nothing ). I'm finally going to get a new aluminum cap on my ( New to me ) truck ) this coming Wednesday, and it will be time to think about a new antenna placement mod to the cap. Keep in mind I'm sort of a Die hard, Hard Head about the antenna is best kept in the center of the roof line for best signal radiation pattern. That's why I went with a aluminum cap & I'm also a metal fabricator, so I'm up to modifications. But I think it would be easier to design a lay down mount ( on the side of the cap ) for a NGP antenna for the times of putting the truck in the garage on a lift. So I ask the Pros ( Are those NGP Antennas worth considering or a waste of time & money ) ??????????

 

[FlyBoy50]

I can't believe I've got no response yet, so thought I would freshen up the question. No time for Napping ! LOL

 

[TM86]

If it were me I’d be looking bonding the cap to the vehicle ground and using it as part of the groundplane. NGP would be good for a plastic or fiberglass body, since it uses at least part of the coax length for a counterpoise. But if you’re throwing a big chunk of metal over the bed of the truck why not take advantage of it?

But then again, I AM a weirdo.

 

[nomadradio]

NGP antennas are a half-wavelength stinger. The feedline length is an odd quarter-wavelength. The coax braid does not connect to the antenna.

This makes the coax a step-up impedance transformer. The loading coil on the stinger makes it functionally a half-wave radiator with a high feedpoint impedance way above 50 ohms. And this is why the coax shield is typically NOT connected to the antenna.

Biggest disadvantage is RF on the outside of the coax shield, and dancing around on the radio's chassis. Bonding the radio chassis to the vehicle's chassis ground is easier said than done these days but it may help reduce having the radio become part of the antenna.

73

 

[FlyBoy50]

If it were me I’d be looking bonding the cap to the vehicle ground and using it as part of the groundplane. NGP would be good for a plastic or fiberglass body, since it uses at least part of the coax length for a counterpoise. But if you’re throwing a big chunk of metal over the bed of the truck why not take advantage of it?

But then again, I AM a weirdo.

Thanks and if your a weirdo than I must be a weirdo also because I think like you. A NGP antenna just doesn't set well in my mind but I'm not a electronic wizard either. I'm sure they must work to a certain degree if you have to use them but I'd rather stick with the Tried and & True. But that's coming from a old metal worker ! LOL

 

[FlyBoy50]

NGP antennas are a half-wavelength stinger. The feedline length is an odd quarter-wavelength. The coax braid does not connect to the antenna.

This makes the coax a step-up impedance transformer. The loading coil on the stinger makes it functionally a half-wave radiator with a high feedpoint impedance way above 50 ohms. And this is why the coax shield is typically NOT connected to the antenna.

Biggest disadvantage is RF on the outside of the coax shield, and dancing around on the radio's chassis. Bonding the radio chassis to the vehicle's chassis ground is easier said than done these days but it may help reduce having the radio become part of the antenna.

73

Thanks Nomad and I'm laughing because your way above my Metal Head. LOL This old Dog will go in the corner and lick his wounds. LOL

 

[gamegetter]

FB50, no reason to feel bad about not understanding things, it's why the forum is here for all to learn. in time you will learn and this is a good place to do so.

Let us know when you make progress on the antenna install and post a pic of that bad boy once you get it set up.

enjoy the hobby.

 

[FlyBoy50]

FB50, no reason to feel bad about not understanding things, it's why the forum is here for all to learn. in time you will learn and this is a good place to do so.

Let us know when you make progress on the antenna install and post a pic of that bad boy once you get it set up.

enjoy the hobby.

Thanks for the vote of confidence and that is why I joined several radio forums. For the most part there is a bunch of Great guys eager to help a Green Horn learn. All my training has been in Repair, Maintenance, & metal Fab. And nothing in electronics, but sometime you can do OK with some common sense also. LOL But some training sure would help also. My project will probably have to wait until Spring any way so I can pull the cap off the truck, but gives me time to figure out what avenue I want to take. If you add steel to aluminum it sets up a corrosive action so that is something you have to consider also. But I could add a aluminum plate to the aluminum cap and bore a hole down threw that and that wouldn't hurt my feelings as bad as doing the truck roof. LOL Sometimes some fore-thought is better that Would Have, Could Have, Should Have !