{"id":148,"date":"2016-12-23T13:46:12","date_gmt":"2016-12-23T13:46:12","guid":{"rendered":"https:\/\/klubnl.pl\/wpr\/?page_id=148"},"modified":"2016-12-23T14:33:14","modified_gmt":"2016-12-23T14:33:14","slug":"dopasowanie-anteny-longwire-na-pasmach-kf-i-630m","status":"publish","type":"page","link":"https:\/\/klubnl.pl\/wpr\/en\/artykuly\/dopasowanie-anteny-longwire-na-pasmach-kf-i-630m\/","title":{"rendered":"Operating a longwire on VLF, 630m and 160m-17m via a simple matching circiut"},"content":{"rendered":"

HAMs often need to use compromise antennas, which they try to force into use on as many bands as possible. A longwire is an often used antenna – the antenna wire between buildings doesn’t attract unneded attention as long as it doesn’t have any distinctive features (such as in a dipole).<\/p>\n

I live in a typical concrete apartament building, which limits instalation of large antennas. For a long time the only antenna i had was a 40m longwire between two 5-story buildings. This antenna has to be enough for all HF bands 160-17m, for 630m and for VLF. For this reason i installed a multiband matching circuit on the roof, remotely operated via relays.<\/p>\n

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40m longwire VLF\/630m\/160-17m match<\/figcaption><\/figure>\n

The relays switch the longwire between a matching transformer for all bands 160-17m. The ratios are 1:1, 4:9, 1:4 and 1:9. This is 14 windings trifilar on an Amidon T200-2 core.<\/p>\n

There is a transformer for VLF. This is from an old TV HV circiut. The secondary is resonant with the 200pF antenna capacitance at around 8kHz. The primary winding is 10 turns.<\/p>\n

There is also a coil for 630m, with additional coils switch in series to allow fine tuning. To achieve a small size, the main coil is wound on a large ferrite rod. This is called an impeder rod, and is used in induction welding of pipes.<\/p>\n

A series coil matching circiut has the disadvanvage that there is no control of the impedance. My antenna had 12 ohms at resonance. Further matching is done by a 7nF capacitor to ground, which is connected not on the roof, but at the other end of the coax cable at home. This is probably less efficient than a large coil with switched tap, but is much smaller and doesn’t require as much trips to the roof for retuning. Below is a simplification of this LC circuit, with only the 630m tuning coil shown.<\/p>\n

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The VLF matching circuit could also be exchanged for another coil for the 136kHz band.<\/p>\n

Author: Jacek \/ SQ5BPF<\/p>\n","protected":false},"excerpt":{"rendered":"

HAMs often need to use compromise antennas, which they try to force into use on as many bands as possible. A longwire is an often used antenna – the antenna wire between buildings doesn’t attract unneded attention as long as it doesn’t have any distinctive features (such as in a dipole). I live in a … Continue reading “Operating a longwire on VLF, 630m and 160m-17m via a simple matching circiut”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":125,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-148","page","type-page","status-publish","hentry"],"translation":{"provider":"WPGlobus","version":"3.0.1","language":"en","enabled_languages":["pl","en"],"languages":{"pl":{"title":true,"content":true,"excerpt":false},"en":{"title":true,"content":true,"excerpt":false}}},"_links":{"self":[{"href":"https:\/\/klubnl.pl\/wpr\/en\/wp-json\/wp\/v2\/pages\/148","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/klubnl.pl\/wpr\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/klubnl.pl\/wpr\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/klubnl.pl\/wpr\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/klubnl.pl\/wpr\/en\/wp-json\/wp\/v2\/comments?post=148"}],"version-history":[{"count":6,"href":"https:\/\/klubnl.pl\/wpr\/en\/wp-json\/wp\/v2\/pages\/148\/revisions"}],"predecessor-version":[{"id":157,"href":"https:\/\/klubnl.pl\/wpr\/en\/wp-json\/wp\/v2\/pages\/148\/revisions\/157"}],"up":[{"embeddable":true,"href":"https:\/\/klubnl.pl\/wpr\/en\/wp-json\/wp\/v2\/pages\/125"}],"wp:attachment":[{"href":"https:\/\/klubnl.pl\/wpr\/en\/wp-json\/wp\/v2\/media?parent=148"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}