1996 - 2016
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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When a structure is measured for an official height, it includes every part of the structure - including the antenna(s) and support mast(s) that is(are) almost always included at the very top. Take the current height record holder, the Burj Khalifa, in Dubai, for instance. The overall height of the structure including the antenna is 828 meters; however, the antenna is 207 meters tall, so the building itself is only 621 meters. As can be seen from the chart below, only two pure antennas (including support mast) are included in the world's tallest structures. Antennas are used for television, radio, data, and even optical transmission.
If you read Arthur C. Clarke's article in the October 1954 edition of Wireless World where he conceived of a geosynchronous satellite system to broadcast television signals rather than using a series of terrestrial towers, it is apparent why even using antennas at heights like the one on the Burj Khalifa would not even come close to providing coverage needed for the entire earth. The following table gives the line-of-sight*, including earth curvature, range for each antenna (assuming maximum specified height). With an earth circumference of 40,000 km, you would need nearly 700 towers just to provide continuous coverage along the equator. A few thousand would be required for global coverage. The logistics for construction, maintenance, and operation of such a network would be daunting... if not impossible. Imagine the aerial navigation that such an array would pose!
|Name||Location||Height (AGL)||LoS Range (km)|
|Burj Khalifa||Dubai||828 m||119|
|Warsaw Radio Tower||Poland||646 m||105|
|Tokyo Sky Tree||Japan||634 m||104|
|Guangzhou (Canton) Tower**||China||600 m||101|
|CN Tower||Canada||553 m||97|
|Sears (Willis) Tower||USA||527 m||95|
|Oriental Pearl Tower||China||468 m||89|
|Empire State Building||USA||443 m||87|
|Eiffel Tower||France||324 m||74|
* Line-of-Sight Calculator
Graph of World's Tallest Structures - Including Antennas
Well, this started out being about pictures of high antennas (i.e., Cool Pic), but it kind of evolved into a little more.
These images have been chosen for their uniqueness. Subject matter ranges from historic events, to really cool phenomena in science and engineering, to relevant place, to ingenious contraptions, to interesting products (which now has its own dedicated Featured Product category).
Cool Pic Archive Pages
Posted July 11, 2011