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| mission:log:2012:08:02:active-wideband-receiver-antenna-for-sdr [2015-05-05 18:14] – [Active Wideband Receiver Antenna for SDR] chrono | mission:log:2012:08:02:active-wideband-receiver-antenna-for-sdr [2025-04-24 17:44] (current) – chrono | ||
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| ==== Antenna Element ==== | ==== Antenna Element ==== | ||
| - | The antenna element itself is a simple quadrilateral monopole, in the shape of a wedge, with a narrow start and a wider end. For lack of a common nomenclature and a relatively close optical proximity to a log-per design, this type is going to be ignorantly called // | + | The antenna element itself is a simple quadrilateral monopole, in the shape of a wedge, with a narrow start and a wider end. For lack of a common nomenclature and a relatively close optical proximity to a log-per design, this type is going to be ignorantly called // |
| - | [{{: | + | [{{: |
| - | er Antenna Element}}] | + | |
| [{{: | [{{: | ||
| [{{: | [{{: | ||
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| ~~CL~~ | ~~CL~~ | ||
| \\ | \\ | ||
| - | The small start of the original copper log-per-spiral begins at a 25mm offset from the bottom part of the white, rolled 80mm cylinder, the wider end extends 75mm over the upper edge. After 55mm from the edge of the white cylinder, the rest of the copper is bent around the outer tube and then covered by the cap. This has probably no effect on RF properties (can someone verify this?) but is probably a way to give the whole structure more mechanical support. | + | The small start of the original copper log-per-spiral begins at a 25mm offset from the bottom part of the white, rolled 80mm cylinder, the wider end extends 75mm over the upper edge. After 55mm from the edge of the white cylinder, the rest of the copper is bent around the outer tube and then covered by the cap. This has probably no effect on RF properties (can someone verify this?) but is probably a way to give the whole structure more mechanical support. |
| + | |||
| + | For easier replication, | ||
| <WRAP round download> | <WRAP round download> | ||
| **Downloads: | **Downloads: | ||
| - | [[https:// | + | {{: |
| + | [[https:// | ||
| </ | </ | ||
| === Properties === | === Properties === | ||
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| [[http:// | [[http:// | ||
| - | [[http:// | + | [[http:// |
| ==== Structure Tube ==== | ==== Structure Tube ==== | ||
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| [[http:// | [[http:// | ||
| + | ==== NEC2 Simulation ==== | ||
| + | |||
| + | First NEC2 Simulation efforts by Samuel Burri: | ||
| + | |||
| + | {{: | ||
| + | |||
| + | https:// | ||
| ===== LNA ===== | ===== LNA ===== | ||
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| ~~CL~~ | ~~CL~~ | ||
| ==== Alternative LNA Proposals ==== | ==== Alternative LNA Proposals ==== | ||
| + | |||
| + | === BFP420 === | ||
| Due to the venerable age of the original LNA, it is very likely, that more recent semiconductors can deliver superior performance compared to the old design. The LNA is going to be replaced by a new LNA based on Infineons BFP420 which is cheap and available and should perform equally or better. The following two schematics show typical LNA configurations for the BFP420, the left one is the most simple approach (to be tested first), the right picture shows a more refined approach, with better base/ | Due to the venerable age of the original LNA, it is very likely, that more recent semiconductors can deliver superior performance compared to the old design. The LNA is going to be replaced by a new LNA based on Infineons BFP420 which is cheap and available and should perform equally or better. The following two schematics show typical LNA configurations for the BFP420, the left one is the most simple approach (to be tested first), the right picture shows a more refined approach, with better base/ | ||
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| * Each setup with and without a high-pass filter after the antenna element | * Each setup with and without a high-pass filter after the antenna element | ||
| - | <WRAP round tip> | + | === OK3ZB ARA-2000 LNA === |
| - | **Somebody was also thinking in these directions: | + | |
| - | http:// | + | |
| + | {{: | ||
| + | {{: | ||
| - | </WRAP> | + | See also: http:// |
| + | === LNA4All === | ||
| + | |||
| + | http:// | ||
| ==== Ultra-Cheap LNA alternatives ==== | ==== Ultra-Cheap LNA alternatives ==== | ||
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| [{{: | [{{: | ||
| - | This is a close-up of the inside PCB and the used MMIC. Confusingly the pin-numbering of the MMIC is obviously | + | This is a close-up of the inside PCB and the used MMIC. Confusingly the pin-numbering of the MMIC is obviously |
| [{{: | [{{: | ||
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| [[mission: | [[mission: | ||
| [[mission: | [[mission: | ||
| - | [[mission: | + | [[mission: |
| + | [[mission: | ||
| </ | </ | ||