When running a campaign targeted around a very specific location, the best way to hit the right area is usually ‘radius targeting’… drawing a circle of any size around your target spot, to show your ads to users in the area within it.
How large you’ll want that circle to be depends on factors including budget, the size of the available audience, and how proximity-sensitive your service/product is…
But what if you want to test the effect on your traffic of distance-from-source… or you need to target a relatively large area, but you’re pretty sure that conversion rate will tail off, the farther out your users are?
Then draw a circle within a circle, and bid higher within the closer area.
You will often find that this works as you’d expect… as in the example above. The closer in to your target, the better your conversion rate and cost per conversion.
Results will vary, but whatever you find, you can use this new insight to optimise bids in the area ‘donuts’ you’ve created… raising them to make more of your better-converting traffic, and cutting them where your clicks become less valuable.