I know this is more about placing an antenna on a vehicle and having directional qualities because of where you place it but I have a weird dilemma with a base antenna
I've had the same antenna on my small repeater at my shop and it has given me mediocre results ever since I put it up there. After we had some wind my cheap mount folded and the antenna leaned. I straightened it up and reinforced it best I could and life went on.
Then another agressive wind came around for a solid week and the mount failed again. The antenna was at about a 15º lean and the repeater was contacting my house very well. Thought it was odd. So after the winds died down after a week I got a much sturdier replacement for my mount and got the antenna up vertical again. It's about 2' lower because I separated the mounting brackets more to take the leverage the wind produces on the mast.
I could get to my house base station, the wife said I was coming in great. She on the other hand was barely making the repeater. And when she was it was horrible. So last night I started testing with a voice activated recorder. Driving away from the repeater toward the house calling out at different streets til I reached my driveway, tested there with an HT and then in the house testing the base station.
I did this 4 times with not great results. Found that the HT I use normally in the shop wasn't doing a great job and swapped it out. Tested in the shop and then in the office. I went up on my ladder and loosened up the mount and turned the antenna about 10º and now it started to come in better. I still don't know as of yet if it'll work as good as the test I did last night. But that test was very good. It always comes in better later at night than in the normal work hour time.
So I'm just wondering why my omnidirectional antenna seems to be far from omnidirectional. Seems like there is a distinct lobe that has a 20dB or more lack of power. The repeater is about 42 watts and the house base is 25 watts, both measured out the backside of the radio. House is 84' LMR400 and the shop is 50' LMR400. It's line of sight but heavily treed.
More testing will be done today, this time not all by myself.