Microwave Ovens 101
Mar 30 '00
A History and How-To on Buying a Microwave
To paraphrase expert, J. Carlton Gallawa*: “A microwave oven is a specially-fashioned metal box with an opening into which is fed microwave power. The energy entering the box is unable to escape, thereby creating a higher density electromagnetic field. When food is placed in the box and microwave energy fed in, the temperature of the food rises very rapidly. Dr. Percy L. Spencer invented what would revolutionize cooking and form the basis of a multimillion dollar industry, the microwave oven.”
Microwaving or the ability to satisfy our needs for instant gratification can be traced back to a self-educated man with a sweet tooth. If Percy Spencer had a penchant for cashews, we might still boil water using the stovetop and a kettle. For the sake of those who find my ramblings a bit much, my advice on how to buy a microwave oven precedes the abridged version of the history of this appliance.
Advice on Buying a Microwave Oven:
The considerations are many as are the options offered by various manufacturers of microwave ovens. The first determination would logically be where you are going to situate the appliance. The three main options are as follows:
· Countertop Ovens: The majority of microwave ovens purchased are this type. Whether situating the oven on the kitchen counter or using a microwave cart to free up counter space, these are the workhorses of the American kitchen. Readily available in discount super-stores, appliance supermarkets and mom and pop establishments; locating the right microwave oven for your needs is a simple matter.
· Over-the-range Ovens: Over-the-range ovens replace the exhaust hood over the stovetop. Most incorporate a light and a vented or circulating exhaust fan below the oven. These units require an electrician’s expertise to install and additional carpentry work on existing homes. For those purchasing or building a new home, this is always a viable option. The over-the-range model frees countertop real estate for other appliances. These models are more expensive but often have larger than average capacity ovens. Unless you are planning to remodel your kitchen, this might not be the best choice.
· Built-in Ovens: Many counter-top microwave ovens afford the option of installation as built-in models. Templates and additional hardware specifically made for this purpose are readily available from appliance retailers and manufacturers. Like the over-the-range ovens, you gain counter space. The main drawback is the loss of cabinet space with this type of installation.
Once you decide upon the type, style, color and preferred manufacturers, the next seven considerations come into play:
· Size and Capacity: If all you require is an appliance to heat coffee or frozen entrees, a small unit should suffice. Available in sizes ranging from a miniscule 0.4 square feet up to over two square feet in capacity, there are microwave ovens available for every need. Advances in insulation properties permit larger oven capacities while barely increasing exterior dimensions. Available counter space and utility are the criteria to go by unless purchasing an over-the range model. Those models are often larger in capacity than mid-sized counter-top models.
· Wattage: The higher the wattage, the faster the cooking cycle. In a 600-watt oven, eight ounces of water heats to its boiling point in approximately two minutes. The time consumed in reaching the same results diminishes appreciably as the wattage increases. Ovens on the current market offer wattage as low as 550-watts and as high as 1100-watts. As the wattage increases, so does the appliance’s price. Consider what you plan to use the oven for and decide accordingly which would best serve your purposes.
· Turntable: Most microwave ovens come with a built-in turntable. Years ago, if we wanted the advantage of having our food rotated automatically, purchase of a wind-up turntable was the only solution. When manufacturers began including this feature in most units, the advent was welcomed but also presented a problem. Turntable jam larger dishes or rectangular pans into one corner of the oven resulting in unevenly heated foods. After years of our adjusting to this problem, manufacturers finally listened to our complaints. Many newer microwaves offer an “On/Off Turntable” switch that eliminates these concerns. This writer considers this feature, found on mid-line to high-line microwave ovens, a necessity.
· Convection/Microwave Combinations: Purchasing a dual-purpose oven requires digging deeper into your wallet. Those who want the ability to not only nuke or defrost their food but want to bake, roast and combine those methods will find the convection/microwave pairings ideal for their purposes. Two separate internal components afford the variety of applications. These ovens are generally larger than most single-purpose units are but take the place of several appliances. The ability to partially microwave meats and casseroles then follow immediately by roasting and browning by convection is a nice plus. As with most multi-purpose appliances, if one element goes bad, the entire unit might become inoperable.
· Sensor Cooking 1: Some of the higher end microwave ovens come with a probe used for sensor cooking. Insert the probe into the food and hit the Sensor Cook button. The probe tests for heat and moisture content. The oven turns off when the probe’s sensors determine the cooking process is complete. This sounds wonderful. It also gives us all another object to hand wash. The probes in older models were not accurate enough to become desirable features. This option failed to bring the acclaim of the turntable’s inclusion. Finding models with the “probe” might prove difficult.
· Sensor Cooking 2: With the latest innovations in microwave cooking, the word “sensor” takes on a new definition. Sensors within the oven measure the humidity and temperature of the inside oven atmosphere. When choosing to use sensor cooking, the technology takes over and determines the doneness of the food. It notifies you with a sound and turns off the oven.
· Rack: Over-the-range models and some countertop ovens often come with an additional rack. This permits microwaving two larger items at one time. One dish rests on the turntable and the other on the wire rack located mid-way between turntable and the top of the oven. While some may find the additional rack convenient, I feel otherwise. The placement of the grid wires on the rack seem too far apart to evenly support bowls, cups or mugs. I found myself removing the rack more often than not, which was an inconvenience. The concept of microwave cooking is “quick and easy” not “disassemble and stow.” For larger families, this feature might be a consideration. Remember, two plates of food take longer to cook than one and dishes placed on the rack must be manually turned for even heating.
· Specialized “Wave” Systems: Many newer microwaves offer Superwave®, Ultra-Wave®, Windmill® or other trademarked microwave stirring systems. Essentially what these boil down to are a fan assembly and a series of embossments on the interior oven walls. The fan redistributes the microwave energy in every direction within the oven. The microwaves then bounce off the embossments in a pattern allowing even distribution throughout the oven. According to the manufacturers, the process results in even heating, cooking and defrosting.
Every line of microwave touts special features. Deciding which ones are right for you is simply a matter of taste. Additional options to consider are:
· Electronic Touch Pad Controls – easily wipe clean
· Dial Controls – easier for those with poor eyesight
· Push Button Door or Manual Operation
· Multiple Defrost cycles
· One-touch Keys for Popcorn, Beverages, etc.
· Digital Readout Panels
· Additional Kitchen Timer
· Advanced Programming – offering customization
· Child Lock-out and Safety Features
A History of the Microwave Oven
Fifty-four years ago, Dr. Percy Spencer developed a case of the munchies. The chocolate bar neatly tucked into his pocket seemed a likely solution for the esteemed research scientist’s sweet tooth dilemma. Taking temporary leave from his experiments on the magnetron tube, Dr. Spencer reached into his pocket only to find chocolate syrup. Logic dictated that body heat did not create this phenomenon. He carried chocolate bars in his pockets on a regular basis. At worst, the candy would soften but never before melted to a pure liquid consistency.
As any dedicated scientist will tell you, the next step was obvious. Popcorn! Since the errant rays produced during testing the magnetron tube cooked his cocoa, the device required further trials with other food products. The bag of kernels placed next to the magnetron popped within minutes. Following that success, the good doctor tested the principle on whole eggs. The bouncing rays caused the ovum to burst, much to his delight. Holding it next to the tube, a colleague ended up with egg on his face - hence the expression. (Okay, I just threw that in, sorry.)
Hitler and the Nazi regime were the catalysts for developing a wide array of advanced weapons of war during the late 1930s and 1940s. In a lab at England’s Birmingham University, two scientists, Dr. H. A. Boot and Sir John Randall, invented a microwave producing device called a magnetron. A key component to radar, development of the technology afforded the Allies the ability to bounce rays off AXIS weapons allowing detection by our side. After World War II, the technology needed a new purpose. Raytheon Corporation® and Dr. Percy L. Spencer took on the task of giving the magnetron a peacetime application.
Brilliant and focused on creating a marketable product for his discovery, Dr. Spencer immediately considered the fact that if the rebounding rays cooked his candy and eggs, they most likely did a number on ‘his’ cookies. Containing the rays within a sealed environment, the good doctor created the first microwave oven.
The original Radarange™ measured a whopping five and a half feet tall, weighing in at seven hundred and fifty pounds. Initially sold as a commercial oven with a price tag of two to five thousand dollars; the microwave achieved limited acceptance and utilization by restaurants, ocean liners and railroads. Original units required water-cooling the magnetron necessitating extensive plumbing renovations. Compact units came into being once developers perfected the air-cooled magnetron, which eliminated keeping a plumber on retainer. It was not until Tappan® introduced a scaled down but still refrigerator-sized version in 1952, that microwave cooking became a consideration for home use (priced at $1,295.00). The new technology took off in only the wealthiest of families and even then, only with reservations regarding safety concerns.
Raytheon Corporation® acquired Amana Refrigeration® in 1965. The first counter-top units went on the market two years later. At under $500.00, the smaller 100-watt ovens were safer and more reliable than their predecessors were. The present day microwave ovens share the same basic configuration. The technology remains a constant. By pushing the start button, we duplicate the results of Dr. Spencer’s experiments.
Percy Spencer served as a senior consultant with Raytheon® until his death in 1970. Dr. Spencer held one hundred and fifty patents at the time of his passing at age 76. A self taught man, he was considered one of the world's leading experts in the field of microwave energy, despite his lack of a high school education.
Dr. Percy LaBaron Spencer was inducted into the National Inventors Hall of Fame on September 18, 1999. Honored for all time, his place in history is secure.
Thank you Percy Spencer! We salute you!
References and Credits:
Who Invented Microwaves* at:
http://www.gallawa.com/microtech/history.html
Useless Information at:
http://home.nycap.rr.com/useless/microwaves/microwav.html
How Things Work – Microwaves at:
http://rabi.phys.virginia.edu/HTW//microwave_ovens.html
Inventor of the Week at:
http://web.mit.edu/invent/www/inventorsR-Z/spencer.html
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