try searching for "fire pit" -- a lot of them are elevated and might fit the bill for you. I don't have a specific product in mind though.

Before you get an onslaught of recommendations for products that might not fit the bill, or are not available in your area, you should check out your local retailer. Give them your requirements and get a list of products. Then post that list for Houzz and people can comment on style and brand selection.

Check your local codes before buying, especially for on your deck. Most tables have the tanks inside them, so its all in one package, and also for added wights in windy storms. You coulg put the tank elsewhere and plumb a line it ya wanted to, but you’re still going to have to refill that tank at some point in time.

Regarding the heat, heat will rise, and likely not give off a ton outwards. If you have to keep them away from your furniture, it will likely not be enough heat for your purpose.

These are a nice product: http://americanfyredesigns.com/firetablesandfirebowls/firetables-2/

There's a "where to buy" button on the website to find a local dealer. They're better quality than most of what you'll find in a box store.

Almost every home in my development has a fire pit. As long as you sit close to it, the warmth is enough to enjoy staying outside when it's 10 degrees below your comfort zone.

We've got a CampChef brand propane table (it has a bbq size propane tank inside it). It worked well on our little 20x20 deck in the townhouse. You can get some heat from it if you sit close.

Don't be limited by off the shelf products. You can customize thereby having a remote tank.