You’ll see larger capacity, sensors that detect doneness, and stylish designs.

Microwave ovens, which built their reputation on speed, are also showing some smarts. Many automatically shut off when a sensor determines that the food is cooked or sufficiently heated. The sensor is also used to automate an array of cooking chores, with buttons labeled for frozen entrées, baked potatoes, popcorn, beverages, and other common items. Design touches include softer edges for less boxy styling, hidden controls for a sleeker look, stainless steel, and, for a few, a translucent finish.

WHAT’S AVAILABLE

GE leads the countertop microwave-oven market with approximately 25 percent of units sold, followed by Sharp. Other brands include Panasonic, Emerson, and Kenmore. GE also sells the most over-the-range models.

Microwaves come in a variety of sizes, from compact to large. Most sit on the countertop, but a growing number sold--about 13 percent--mount over the range. Several brands offer speed-cooking via halogen bulbs or convection. Speed-cook models promise grilling and browning, though results can vary significantly depending on the food. Manufacturers are working to boost capacity without taking up more space by moving controls to the door and using recessed turntables and smaller electronic components.

Microwave ovens vary in the power of the magnetron, which generates the microwaves. Midsized and large ovens are rated at 900 to 1,500 watts, compact ovens at 600 to 800 watts. A higher wattage may heat food more quickly, but differences of 100 watts are probably inconsequential. Some microwave ovens have a convection feature--a fan and, often, a heating element--which lets you roast and bake, something you don’t generally do in a regular microwave.

Price range: $40 to $250 (countertop models); $150 to $500 (over-the-range); $250 to $700 (convection or halogen-bulb countertop or over-the-range).

IMPORTANT FEATURES

On most, a turntable rotates the food so it will heat more uniformly, but the center of the dish still tends to be cooler than the rest. With some models, you can turn off the rotation when, for instance, you’re using a dish that’s too large to rotate. The results won’t be as good, however. Some models have replaced the turntable with a rectangular tray that slides from side to side to accept larger dishes. Most turntables are removable for cleaning.

You’ll find similarities in controls from model to model. A numeric keypad is used to set cooking times and power levels. Most ovens have shortcut keys for particular foods, and for reheating or defrosting. Some microwaves start immediately when you hit the shortcut key, others make you enter the food quantity or weight. Some models have an automatic popcorn feature that takes just one press of a button. Pressing a 1-minute or 30-second key runs the oven at full power or extends the current cooking time. Microwave ovens typically have a number of power levels. We’ve found six to be more than adequate.

A sensor helps prevent over- or undercooking by determining when the food is done based on infrared light or the steam emitted by food. The small premium you pay for a sensor is worth it. A few ovens have a crisper pan for making bacon or crisping pizza, since microwave cooking without the special pan leaves food hot but not browned or crispy.

Over-the-range ovens vent themselves and the range with a fan that has several speed settings. Typically the fan will turn on automatically if it senses excessive heat from the range below. Over-the-range microwaves can be vented to the outside or can just recirculate air in the kitchen. If the oven is venting inside, you’ll need a charcoal filter (sometimes included). An over-the-range microwave generally doesn’t handle ventilation as well as a hood-and-blower ventilation system because it doesn’t extend over the front burners.

HOW TO CHOOSE

Decide which type meets your needs. Countertop models cost the least and are best for kitchens with lots of counter space. Compact models can cost as little as $30. Midsized and large models have more capacity and features, though most eat up 1 1/2 to 2 feet of length of countertop space. You can hang some countertop models below a cabinet, though doing so often leaves little space below the microwave oven.

You’re likely to consider an over-the-range oven only if you’re replacing one or remodeling your kitchen. While they save counter space, installation is an added expense and often requires an electrician. What’s more, they can’t vent steam and smoke from a range’s front burners as well as the range hoods they replace.

Choose convenience, not clutter. There’s little reason to buy a microwave without a sensor, which shuts off oven power when it senses the food is hot; sensor models begin at about $85. But you may want to avoid ovens with an array of shortcut and defrost settings for foods you don’t eat.

Keep convection in perspective. Browning and crisping via convection are great if you use a microwave as a second oven. But if you’re buying one mostly for heating and defrosting, consider a lower-priced nonconvection model.

Be wary of capacity claims. Oven makers often measure corner space you can’t use; actual space can be 50 percent to 60 percent less than they claim. Check whether a large platter fits an oven you’re considering.

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