Poor reception with mag mount antenna

[Rulander]

I have a brand new 45w mobile unit that I just got a few days ago. I was going to use it in my truck, but am now thinking it would make a better base station unit. The other day, I just popped the hood of said truck, hard wired it to the battery, and slapped the mag mount antenna on the roof just to see if I could hear anybody and get a radio check. I hit a repeater over 40 miles away and got great reports. 

Today, I wanted to do the same thing, but as a temp base station. I have a huge R panel metal roof that covers my back porch (approx 800sqft). Wired up to a yellow top Optima battery, put the mag mount on the roof, and started listening. My 5w HT was picking up traffic that I couldn't pick up on the mobile unit. There were no differences in freq's, or tones used. It just flat didn't work well at all. What am I missing?

[Socalgmrs]

14 minutes ago, Rulander said:

I have a brand new 45w mobile unit that I just got a few days ago. I was going to use it in my truck, but am now thinking it would make a better base station unit. The other day, I just popped the hood of said truck, hard wired it to the battery, and slapped the mag mount antenna on the roof just to see if I could hear anybody and get a radio check. I hit a repeater over 40 miles away and got great reports. 

Today, I wanted to do the same thing, but as a temp base station. I have a huge R panel metal roof that covers my back porch (approx 800sqft). Wired up to a yellow top Optima battery, put the mag mount on the roof, and started listening. My 5w HT was picking up traffic that I couldn't pick up on the mobile unit. There were no differences in freq's, or tones used. It just flat didn't work well at all. What am I missing?

How about squelch setting on the base unit?   Are all connections tight?   Anytning In the way of line of sight? 

[BoxCar]

Antenna height.

[Rulander]

2 minutes ago, WRXP381 said:

How about squelch setting on the base unit?   Are all connections tight?   Anytning In the way of line of sight? 

Everything tight, battery is fully charged. The roof is flat and about 8 ft tall. Antenna is maybe 1.5' tall. The roof of the house is in front of the antenna, but nothing to the sides, or behind. My HT was actually under the roof picking up well. 

[Rulander]

5 minutes ago, BoxCar said:

Antenna height.

Total height is maybe 9-10'. It's a short antenna. It's sitting a few feet higher that it was when it was on the truck. 

[SteveShannon]

On the porch roof?  Is it sloped down away from the repeater by any chance?

Is there a higher elevation roof?

[Rulander]

1 minute ago, SteveShannon said:

On the porch roof?  Is it sloped down away from the repeater by any chance?

Is there a higher elevation roof?

It doesn't have much fall, maybe 2 inches. All of the higher elements of the roof are composite shingles. Only the porch roof is metal. 

If I decide for sure that I want this to be a base station, I'd definitely get a better set up. I was basically doing a trial run. Was just expecting better results. I do have a 20' mast laying around somewhere that I used for CB many years ago. I suppose I can erect it again and get a better antenna. I just wasn't sure if I was overlooking something with this temporary setup that would help. I suppose it's as good as it going to be as is. 

[GreggInFL]

Don't feel bad, I have the same thing happening.  25W mobile with a mag mount is easy 15-20 miles, but I move the rig inside on a pie pan and it performs worse than an HT.  Telling Santa I want a real antenna.