{"id":7915,"date":"2014-05-23T08:00:56","date_gmt":"2014-05-23T12:00:56","guid":{"rendered":"http:\/\/www.engineeringradio.us\/blog\/?p=7915"},"modified":"2023-03-26T09:55:16","modified_gmt":"2023-03-26T13:55:16","slug":"the-shively-6710-antenna","status":"publish","type":"post","link":"https:\/\/www.engineeringradio.us\/blog\/2014\/05\/the-shively-6710-antenna\/","title":{"rendered":"The Shively 6710 Antenna"},"content":{"rendered":"\n
\"Shively<\/a>
Shively 6710-1 FM antenna<\/figcaption><\/figure>\n\n\n\n

Perhaps that is one Shively Antenna that you haven’t heard of. They were an oddball combination of a horizontally polarized antenna with an adjustable vertical element. This design allowed the station to adjust the ratio of horizontal to vertical power from a range of 1:1 to about 4:1 (H:V).\u00a0 Why would this be a desirable feature?<\/p>\n\n\n\n

Back in the early days of FM broadcasting, almost all stations had horizontally polarized antennas.\u00a0 This system worked remarkably well, stations could broadcast at moderate power levels over fairly long, line-of-sight (or mostly line-of-sight) paths.\u00a0 Most FM receivers were stationary units installed in people’s homes often with outdoor antennas.<\/p>\n\n\n\n

It was not until the late 1960s and early 1970s that FM radio receivers became a stock option in most low and mid-cost automobiles.\u00a0 It was then that a slight problem with FM broadcasting was discovered;\u00a0 car antennas are vertically polarized.\u00a0 People driving around in their new machines found that the FM reception was not all that great.\u00a0 Stations began adding a vertical component to their signal to help improve the mobile reception situation.<\/p>\n\n\n\n

I found this Shively Brochure<\/a> in a file cabinet drawer at the WFLY transmitter site<\/a>.\u00a0 This model antenna was ordered and installed by that station in 1970.\u00a0 It had a 3:1 horizontal-to-vertical ratio.\u00a0 Why not install a fully circularly polarized antenna?\u00a0 Because often that necessitated installing a new, more powerful transmitter.\u00a0\u00a0 Every watt of power taken from the horizontal plane and added to the vertical plane reduced the ERP by that much and had to be made up with more transmitter power output.\u00a0 Oftentimes, the ratio of H:V power would be adjusted to take up whatever headroom there was in the transmitter and the station would run that way until the next transmitter replacement cycle.<\/p>\n\n\n\n

I found the remains of this antenna in the woods, northeast of the tower.<\/p>\n\n\n\n

\"Shively
Shively 6710 antenna section<\/figcaption><\/figure>\n\n\n\n

This section looks pretty well destroyed.\u00a0 It is probably better to dispose of these types of things by scraping, them rather than dumping them in the woods.\u00a0 While there is not a lot of scrap value to this unit, it can become attractive nuisance to copper thieves and other vandals if it is left laying about.<\/p>\n\n\n\n

It is a strange-looking piece of kit, a sort of make-do until the situation could be fully rectified.\u00a0 I think this antenna was in service until 1986 or 87 when it was replaced with a circularly polarized ERI.<\/p>\n","protected":false},"excerpt":{"rendered":"

Perhaps that is one Shively Antenna that you haven’t heard of. They were an oddball combination of a horizontally polarized antenna with an adjustable vertical element. This design allowed the station to adjust the ratio of horizontal to vertical power from a range of 1:1 to about 4:1 (H:V).\u00a0 Why would this be a desirable … Continue reading The Shively 6710 Antenna<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[35,4],"tags":[82,229,243],"class_list":["post-7915","post","type-post","status-publish","format-standard","hentry","category-history","category-tech-stuff","tag-fm","tag-fm-antenna","tag-fm-tansmitter-site"],"_links":{"self":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/7915","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/comments?post=7915"}],"version-history":[{"count":6,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/7915\/revisions"}],"predecessor-version":[{"id":11266,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/7915\/revisions\/11266"}],"wp:attachment":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/media?parent=7915"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/categories?post=7915"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/tags?post=7915"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}