I知 going to put a 2 meter ham radio in my Discovery 2. The ARB bumper has an attachment point for an antenna but I知 wondering if attaching it to the forward area of the hood, just in front of the limb riser would be better. I知 fairly new to radios and have never mounted a mobile antenna. Would it be better to have some hood space below it or does it matter? Thanks.

May be difficult to see but limb riser attaches about 6 inches from front of hood.

 

Yes a ground plane matters. That means optimally sheet metal with an equal distance in all directions... Center of roof/hood/etc.

Of course that is not practical...

The way it works is the antenna will favor the direction in which the most metal is present... So if you put the antenna on the front right bumper your system will favor signals toward the rear left.

Choose the compromise you can live with most because there is no ideal spot with a roof rack.

Also keep in mind if you get one of the really long antennas and tie the end down at the rear your radiation pattern will be pointed at the ground. It will only be useful off road when you can untie it and let it stand upright.

 

Thanks. I知 just learning about ground planes and my thought was some part of the hood would be better than none. Another advantage is the the Comet antenna im looking at can fold and then be secured to the limb riser when not in use. Thanks for your help.

 

A related question, could the limb risers be isolated and function as a 5/8 HF antenna? I currently have no plans to put an HF radio in the vehicle but know similar things are done with back stays on sailboats and are very effective for SSB radios.

 

That works on sailboats because the back stay is way longer than your limb riser. For HF you need a long wire... A short wire won't really do unless it is loaded like the wire of a regular AM antenna on an old car. 5/8 at the length of your limb risers would equal out to be around 2 meters (144mHz,) which is not HF. The wavelength in the middle of the HF band is 30 meters (10mHz...) Your limb risers would be like 1/15 wavelength not 5/8. Then you would have to isolate the limb riser at both ends so it doesn't ground out on the body metal. Bad idea.

Technically if you mount your 2m like the limb riser is mounted you would be mounting to the fender and not the hood... Since they don't actually touch the hood would not help the ground plane.

I would just use the bumper mount. Rear if you want to slightly favor signals in front of you, front if you want to slightly favor signals behind you.

 

THank you. Really appreciate the help.

 

I have a vhf radio installed with a 1/4 wave antenna installed on the front left fender about 10 inches from door openings. Use it to communicate with heavy equip, and logging trucks on the forestry service roads up here in Northern BC. Terrain is mountains, have no issues communicating with trucks several KMs away

 

Mine is up top, attached to my roof bar. The shorty is a bit obscured by the RTT but still works well, you could go off the side of the roof rack

 

Mine is slid out of sight in the body line crack where the tail gate opens. Right side of the tire just a little above the rear bumper height. Works nicely there.