{"id":38920,"date":"2019-08-07T06:44:25","date_gmt":"2019-08-07T10:44:25","guid":{"rendered":"https:\/\/swling.com\/blog\/?p=38920"},"modified":"2019-08-07T06:44:25","modified_gmt":"2019-08-07T10:44:25","slug":"radio-world-history-of-directional-am-broadcast-antennas","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2019\/08\/radio-world-history-of-directional-am-broadcast-antennas\/","title":{"rendered":"Radio World: History of Directional AM Broadcast Antennas"},"content":{"rendered":"

\"\"<\/a><\/p>\n

Many thanks to SWLing Post<\/em> contributor, Marty, who shares the following article by John Schneider in Radio World<\/a>:<\/p>\n

In the early years of AM radio broadcasting, all stations utilized non-directional antennas. Most all of these were wire antennas suspended between towers or buildings. Interference, especially at night, was severe. An interfering signal of 5% or less in signal strength was enough to disrupt reception of the desired station, and if the frequencies of the two stations were slightly separated, there would be a heterodyne beat note. As a result, only a few widely-spaced stations could operate on each of the AM broadcast channels in the entire country at night. This limited the number of stations that could coexist to about 500 nationwide, with many of them sharing time on a single frequency.<\/p>\n

As antenna technologies were developed and improved in the early 1930s, a few progressive stations began experimenting with multi-element directional arrays. This approach offered two attractive benefits: 1) It could reduce radiation towards other stations on the same or adjacent frequencies, permitting more stations to share a frequency; and 2) a broadcaster could direct more signal towards the desired coverage area, and away from wasted areas such as open water in the case of coastal stations.<\/p>\n

WFLA-WSUN<\/p>\n

The first known use of a directional antenna was by a pair of stations in Tampa\/St. Petersburg, Fla. In 1927, the Clearwater Chamber of Commerce acquired station WGHB and changed the call sign to WFLA. A companion station, WSUN, was operated by the St. Petersburg Chamber of Commerce. The two stations shared the frequency of 900 kHz, broadcasting on alternate evenings to promote tourism and business opportunities in their respective communities. In reality, they operated with two station licenses, but there was only one transmitter and one antenna.[…]<\/p><\/blockquote>\n

Click here to to continue reading the full article in Radio World.<\/a><\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

Many thanks to SWLing Post contributor, Marty, who shares the following article by John Schneider in Radio World: In the early years of AM radio broadcasting, all stations utilized non-directional antennas. Most all of these were wire antennas suspended between towers or buildings. Interference, especially at night, was severe. An interfering signal of 5% or […]<\/p>\n","protected":false},"author":15,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[373,3607,433,3],"tags":[6773,7938,7386,3822,634],"class_list":["post-38920","post","type-post","status-publish","format-standard","hentry","category-am","category-antennas","category-mediumwave","category-news","tag-am-antennas","tag-am-broadcast-antennas","tag-class-a","tag-clear-channel","tag-radio-world"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pn3uc-a7K","jetpack-related-posts":[{"id":47162,"url":"https:\/\/swling.com\/blog\/2021\/01\/giuseppes-homebrew-rotating-ferrite-antenna\/","url_meta":{"origin":38920,"position":0},"title":"Giuseppe’s homebrew rotating ferrite antenna","author":"Thomas","date":"January 5, 2021","format":false,"excerpt":"Many thanks to SWLing Post contributor, Giuseppe Morl\u00e8 (IZ0GZW), who writes: Dear Thomas, I'm Giuseppe Morl\u00e8 (IZ0GZW) from Formia, on the Tyrrhenian Sea, in Italy . I built this simple rotating directive ferrite antenna for medium waves and the 160 meters ham band. Inside the tube there are 2 ferrites\u2026","rel":"","context":"In "Antennas"","block_context":{"text":"Antennas","link":"https:\/\/swling.com\/blog\/category\/antennas\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2021\/01\/Double-Ferrite-Antenna-1.jpeg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2021\/01\/Double-Ferrite-Antenna-1.jpeg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2021\/01\/Double-Ferrite-Antenna-1.jpeg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2021\/01\/Double-Ferrite-Antenna-1.jpeg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":59884,"url":"https:\/\/swling.com\/blog\/2024\/06\/the-giant-antennas-of-shanghai-coast-radio-station-xsg\/","url_meta":{"origin":38920,"position":1},"title":"The Giant Antennas of Shanghai Coast Radio Station (XSG)","author":"Thomas","date":"June 2, 2024","format":false,"excerpt":"Many thanks to SWLing Post contributor, Michael (BD4AAQ) who shares the following guest post: Shanghai Coast Radio Station (XSG): Those Giant Antennas! The 17th of May is the World Telecommunication Day. It is also the open day of Shanghai Coast Radio Station. On this day, a group of amateur radio\u2026","rel":"","context":"In "Broadcasters"","block_context":{"text":"Broadcasters","link":"https:\/\/swling.com\/blog\/category\/broadcasters\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2024\/06\/10-300x169.jpeg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2024\/06\/10-300x169.jpeg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2024\/06\/10-300x169.jpeg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2024\/06\/10-300x169.jpeg?resize=700%2C400&ssl=1 2x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2024\/06\/10-300x169.jpeg?resize=1050%2C600&ssl=1 3x"},"classes":[]},{"id":22477,"url":"https:\/\/swling.com\/blog\/2016\/11\/radios-with-rotatable-am-antennas\/","url_meta":{"origin":38920,"position":2},"title":"Radios With Rotatable AM Antennas?","author":"Thomas","date":"November 29, 2016","format":false,"excerpt":"Many thanks to SWLing Post contributor,\u00a0Mario Filippi (N2HUN), who writes: With your broad knowledge of radios, wondering if you can add anything to this list of portable radios, past and present, that have 360 degree rotatable directional AM ferrite antennas. Reason is I am looking for an AM portable for\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"The Panasonic RF-2200 sports a rotatable AM\/MW antenna","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/06\/Panasonic-RF2200-MtMitchell-3-1024x576.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/06\/Panasonic-RF2200-MtMitchell-3-1024x576.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/06\/Panasonic-RF2200-MtMitchell-3-1024x576.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":55580,"url":"https:\/\/swling.com\/blog\/2023\/02\/guest-post-old-fashioned-band-scan-after-the-solar-storms\/","url_meta":{"origin":38920,"position":3},"title":"Guest Post: Old Fashioned Band-Scan after the Solar Storms","author":"Thomas","date":"February 5, 2023","format":false,"excerpt":"Many thanks to SWLing Post contributor, TomL, who shares the following guest post: Old Fashioned Band-Scan after the Solar Storms by TomL This is just an old fashioned band scan to randomly see what I could hear after last week's solar perturbations when the Solar Flux Index went well over\u2026","rel":"","context":"In "Guest Posts"","block_context":{"text":"Guest Posts","link":"https:\/\/swling.com\/blog\/category\/guest-posts\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/02\/NCC2pic.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/02\/NCC2pic.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/02\/NCC2pic.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/02\/NCC2pic.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":55463,"url":"https:\/\/swling.com\/blog\/2023\/01\/radio-waves-shively-labs-broadcast-antennas-fedora-swl-f-150-lightning-am-and-young-listeners-on-the-decline\/","url_meta":{"origin":38920,"position":4},"title":"Radio Waves: Shively Labs Broadcast Antennas, Fedora SWL, F-150 Lightning AM, and Young Listeners on the Decline","author":"Thomas","date":"January 25, 2023","format":false,"excerpt":"Radio Waves:\u00a0 Stories Making Waves in the World of Radio Welcome to the\u00a0SWLing Post\u2019s Radio Waves, a collection of links to interesting stories making waves in the world of radio.\u00a0Enjoy! 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