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- Welcome to the RF Cafe Website Archives -

Established in February of 2014, RFCafe.net is set up as an archival resource for making certain that all information originally presented on RFCafe.com is readily available. PHP

With the exception of required index pages and some images, there is no intentional duplication of content between RFCafe.com and RFCafe.net.

In general, if you can no longer reach a webpage that used to be on RFCafe.com, please change the beginning part of the URL from www.RFCafe.com to www.RFCafe.net and that should solve the issue for you. Example:

From: http://www.rfcafe.com/miscellany/homepage-archive/2014/smart-car-tipping.htm
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I am working to restore as many web pages as possible as far back towards RF Cafe's creation date of July 1999. That's a lot of pages and a lot of images - so many, in fact, that their presence on the RFCafe.com web server was getting bogged down. Thanks, as always, for your loyal patronage of RF Cafe!

 

Sincerely,

Kirt Blattenberger,  Owner / Webmaster 

 

How Radio Waves Are Propagated

How Radio Waves Are Propagated, October 1935 Short Wave Craft - RF CafeIf you or someone you know is just starting in the realm of radio and want a really nice pictorial presentation of the basics of radio wave propagation, then this one-page article from a 1935 edition of Short Wave Craft magazine is just what you need. Formula phobia will not be an issue for anyone since no equations are presented. The fundamentals have not changed in the intervening 89 years, and this same sort of analogy is still used in introductory physics classes and books today. Note in Figure 7 that the antenna for the airplane is shown being dragged behind. Back in the day, a long antenna was spooled out once in the air, and cranked back in before landing. If the pilot forgot to reel the antenna in, it could get yanked off by a tree upon landing. CW (Morse code) was the dominant form of air-to-ground communications...


Electronics-Themed Comics

Electronics-Themed Comics, June 1969 Electronics World - RF CafeThese couple tech-themed comics appeared in the June 1969 issue of Electronics World magazine. The one on page 52 is a bit short-sighted even for its era given that any advanced civilization would likely no longer use vacuum tubes. For that matter, most first-world peoples on Earth were pretty much out of the vacuum tube realm by 1969. New TVs (except the CRT) and radios were almost exclusively solid state. The comic on page 61 made me chuckle out loud when I saw it. That one is worth printing out and framing to hang in the lab or outside an electronics professor's office door.


Electronics-Themed Comics

Electronics-Themed Comics, April & September 1947 Radio-Craft - RF CafeHere are a couple more electronics-themed comics from 1947 issues of Radio−Craft magazine. Artist Frank Beaven, who created a huge number of comics and advertisements (e.g., Eveready batteries, Zippo lighters) for technical and other types of publications (Saturday Evening Post, New Yorker, Esquire), did both of them. Beaven must have a fan base since many examples of his drawings are offered for sale on eBay. Most of his comics credit reader suggestions as the basis for the subject. I have to admit to not really "getting" the gag in the top comic. Maybe Sinatra's voice strained the frequency response of simple tabletop radios of the day. The bottom comic is one of a series entitled "Radio Terms Illustrated," in this example "High Potential" (get it?)...


How Sonar Works

How Sonar Works, October 1961 Radio-Electronics - RF CafeThe fundamental principles of sonar (sound navigation and ranging) and radar (radio detection and ranging) are very similar. Oddly, the author never makes the comparison, and neither does he mention the makeup of the acronym. Although I am no sonar expert, I did work as an electronics technician with sonar system components while at the Westinghouse Oceanic Division in Annapolis, Maryland, back in the 1980s. And, as you might know, I was an Air Traffic Control Radar Repairman in the late 1970s - early 1980s, so I have some experience there, too. While both sonar and radar have their own unique challenges regarding operational environments, I have to say the sonar system designer has more obstacles to overcome than does his radar counterpart. Factors affecting signal propagation which can lead to uncertainty in position, size, and speed are water salinity, temperature, pressure (at great depth), turbidity, turbulence, including often traversing multiple gradients between the source and the target. Wavelengths useful at long distances are too long for fine resolution images, but for close−up inspection, ultrasonic enable near photographic resolution.


90 Miles of Wire in Your Home

The 90 Miles of Wire in Your Home, October 1961 Popular Science - RF Cafe90 miles of wire in an average home is a lot of wire. That includes not just the wire used for supplying 120 VAC receptacle and light lines within the walls and ceiling, but also the wire in motors, relays, and transformers in appliances and various subsystems (HVAC, attic fans, shop tools, etc.). When this article appeared in Popular Science magazine in 1961, the average size of an American home was around 1,300 square feet. In 2024, it is around 2,600 square feet. That's a doubling in size with fewer people per household (mine is smaller than the 1960 standard). The typical house now has more AC wiring in it due to electrical code changes requiring ceiling lights in all rooms, more receptacles, more feeder circuits, etc. Adding a ground wire increases the copper in a length of Romex by 33% to 50%. Most kitchens have more appliances on the counter, and the proliferation of cordless tools has added significantly to the number of motors. Most houses did not have air conditioning in 1961, so add a compressor motor...


Communications Satellites - Success in Space

Communications Satellites - Success in Space, August 1969 Electronics World - RF CafeFrancis A. Gicca, manager of Raytheon's Space Communications Systems, published a very extensive two-part article in Electronics World magazine in 1969. Part 1 covered Score through Intelsat II satellites which launched between from December 1958 and December 1968, respectively, in the July 1969 issue. Part 2 begins with Intelsat III, which commenced operation in September 1968. Rather than reiterating the article's contents, I will offer an anecdote about the altitude used by geostationary satellites, which is 22,300 miles. In the early 1990s, I worked for a few years at COMSAT Laboratories (Communications Satellite Corporation, famous for involvement in both Intelsat and Inmarsat), in Clarksburg, Maryland. The mailing address there was 22300 Comsat Drive...

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