Antenna on Ladder Rack?

[Jericho86]

I just finished my install of my new mobile GMRS setup. 

It's a BTECH GMRS-50V2 and using a Midland mxta26 antenna. I also picked up a Midland ghost antenna, but haven't tried it yet.

The antenna is installed on the highest part of the truck, which is the ladder rack. The rack is steel, and is above the cab, which is also steel. 

I'm assuming that the antenna is too high above the cab to use the sheets metal as a ground plane, is that correct? 

I have attached pictures. The truck obviously needs to be washed. That will happen once we're done cleaning up after Helene. 

[BoxCar]

While there is some truth in what @Socalgmrs sys, the shape of the ground plane isn't as important as it sounds. Your antenna will work fine with a better radiation pattern front and back than to the sides.

[Lscott]

Before you start moving the antenna around and swapping it out for a different model I would do a simple experiment first. Have a buddy a mile or so distance monitor your transmission. Rotate you vehicle in a circle relative to your buddy. If the quality of the transmission, and watch the signal strength, doesn't vary too much then I would just leave it alone. The only really good reason for playing with a different antenna, or it's location, would be for a really poor SWR, something over 2:1. If it's under 2:1 I wouldn't worry about it much.  

[SteveShannon]

12 minutes ago, Lscott said:

Before you start moving the antenna around and swapping it out for a different model I would do a simple experiment first. Have a buddy a mile or so distance monitor your transmission. Rotate you vehicle in a circle relative to your buddy. If the quality of the transmission, and watch the signal strength, doesn't vary too much then I would just leave it alone. The only really good reason for playing with a different antenna, or it's location, would be for a really poor SWR, something over 2:1. If it's under 2:1 I wouldn't worry about it much.  

If after doing this you are disappointed, there are also mounts for ground plane antennas that mount them to the fender.  Although it’s not perfect, it does provide a ground plane and a lot of people get by with fender mounts just fine.  

[Jericho86]

1 hour ago, Lscott said:

Before you start moving the antenna around and swapping it out for a different model I would do a simple experiment first. Have a buddy a mile or so distance monitor your transmission. Rotate you vehicle in a circle relative to your buddy. If the quality of the transmission, and watch the signal strength, doesn't vary too much then I would just leave it alone. The only really good reason for playing with a different antenna, or it's location, would be for a really poor SWR, something over 2:1. If it's under 2:1 I wouldn't worry about it much.  

I will do that this afternoon.

The primary reason I also bought the ghost antenna was to have a lower profile option to keep in the glove box. I'll try that with both.  I've got an SWR meter on the way too. 

I see why people get hooked on this stuff. You can get carried away tinkering if you don't remind yourself that the goal is to just have a properly functioning radio. 

[AdmiralCochrane]

I have successfully used this type of antenna mounting.  I am using it on a small van every day on 70cm and 2m.  In the past I used it on a new tall full sized van with tall ladder racks and always received complements on my signal strength in fringe areas.  Greatest simplex contact was 11 miles.

 

If I understand your picture that the antenna is on the passenger's side rail, your best propagation will be to the driver's side, but you may never actually notice the difference.

 

Don't change a thing.

[Guest]

For a ground plane to work you’re going to need 8-12” of steel or aluminum all around the base of the antenna.  Some people say your set up will work.  It might for limited distance and time.  But a nine ground plane antenna would have solved this issue from the beginning.  I’d say send the antenna back or pack it up for later  use and get a good non ground plane unit.  Right now you have a 50w radio that is neutered on both rx and tx    Even if that ground plane worked you will have a large bias towards the left side