{"id":46679,"date":"2020-12-03T08:11:26","date_gmt":"2020-12-03T12:11:26","guid":{"rendered":"https:\/\/swling.com\/blog\/?p=46679"},"modified":"2020-12-03T08:11:26","modified_gmt":"2020-12-03T12:11:26","slug":"how-to-build-a-simple-linear-loaded-dipole-for-low-noise-shortwave-radio-listening","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2020\/12\/how-to-build-a-simple-linear-loaded-dipole-for-low-noise-shortwave-radio-listening\/","title":{"rendered":"How to Build a Simple Linear-Loaded Dipole for Low-Noise Shortwave Radio Listening"},"content":{"rendered":"

\"\"<\/a>Many thanks to SWLing Post contributor and RX antenna guru, Grayhat<\/a>, for another excellent guest post focusing on compact, low-profile urban antennas:<\/em><\/p>\n

\n

A linear loaded dipole for the SWL<\/h1>\n

by Grayhat<\/strong><\/p>\n

What follows is the description of an antenna which may allow to obtain good performances even in limited space, the antenna which I\u2019m about to describe is a \u201clinearl loaded dipole\u201d(LLD) which some call the \u201ccobra\u201d antenna due to the \u201csnaking\u201d of its wires
\nThe arms of the antenna are built using 3-conductors wire (which may be flat or round) and the 3 conductors are connected this way:<\/p>\n

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

That is, connected \u201cin series\u201d, this means that, the electrical length of the antenna will be three times its physical one; this does NOT mean that the antenna will perform like a single wire of the same (total) length, yet it allows to \u201cvirtually\u201d make it longer, which in turn gives it good performance even with relatively short sizes. Plus, the distributed inductance\/capacitance between the wires not only gives it a number of \u201csub\u201d resonance points, but also helps keeping the noise down (in my experience below the noise you\u2019d expect from a regular dipole).\u00a0 At the same time it offers better performances than what one may expect from a \u201ccoil loaded\u201d dipole. Plus, building it is easy and cheap and the antenna will fit into even (relatively) limited spaces (a balcony, a small yard and so on…).<\/p>\n

Interested–? If so, read on and let me start by showing my (short \u2013 9mt total) LLD installed on a balcony:<\/p>\n

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

Here it is in all its \u201cglory\u201d–well, not exactly–I fiddled with it lately since I\u2019m considering some mods so the tape isn\u2019t correctly stuck and it has been raised and lowered quite some times, but in any case that\u2019s it.<\/p>\n

Bill of Materials<\/h1>\n

Here\u2019s what you\u2019ll need to build it (the links are just indicative, you may pick different stuff or buy it locally or elsewhere).<\/p>\n