libera/#neo900/ Wednesday, 2019-08-14

OksanaHow long is lamba/4 for FM TX? As in, would it be feasible to have stylus with metal core?09:48
Joerg-Neo900ca 45cm09:48
Joerg-Neo900a "stylus antenna" wouldn't improve the FM antenna which is already length of stylus / N90009:49
Oksana45cm?.. That's a lot. Aka, it would have to be telescopic stylus. Tremendously fragile.09:50
OksanaExisting FM antenna is already length of stylus, sounds nice :-)09:50
Joerg-Neo900just though I'd mention it, wasn't a suffestion to run around with a N900 with 45cm "stylus"09:50
OksanaWhat would happen to existing FM TX antenna if stylus was metallic as well? Would it get better or worse?09:51
OksanaYes, running around would not be good...09:51
Oksana:Sigh: So stylus can be plastic or wood, but not metal... What about intricate shape, such as, a metallic spring with tiny stylus diameter and stylus length?09:52
Joerg-Neo900you know, *each* antenna is a dipole. You may consider one half of that dipole be "earth" sometimes. In N900 "earth" gets improved when you plug in USB cable. In stylus bay you may improve the "hot" half09:53
Joerg-Neo900ideally do both for optimum antenna09:53
Joerg-Neo900>>metallic spring with tiny stylus diameter<< tricky, it's running in parallel to a stylus length metal strip that forms the primary antenna. *And* the stylus is way closer to "earh" from PCB ground plane09:55
Joerg-Neo900the latter has detrimental effects when you use metal stylus of original shape09:56
Joerg-Neo900*ideally* you'd use a plastic stylus with two metal surfaces, one close to PCB GND and one close to FM antenna strip. Then connect a closed loop dipole antenna tunes to 100MHz to those two09:58
sixwheeledbeastDoesn't it use the Mic and Ground lines of the TRRS anyway?10:00
Oksanasixwheeledbeast: Only for receiving.10:00
OksanaTransmission is done only on internal antenna.10:00
sixwheeledbeastah sorry i missed TX10:01
OksanaHow long would such a closed loop dipole antenna need to be?10:04
Joerg-Neo900sixwheeledbeast: that's FMRX, not TX10:13
Joerg-Neo900Oksana: tbh I don't know, but "dimensions closed loop dipole 100MHz antenna" should be a good google search string10:15
Joerg-Neo900if I had to guess I'd suggest you start witt 1 Lambda total lenth10:17
Joerg-Neo9003.028206646465m  so lambda/4 isn't 45 but rather 75cm10:20
Joerg-Neo900sorry, no coffe yet10:21
Joerg-Neo900thought "2m band" but that's not 100MHz but quite a bit higher freq10:22
Joerg-Neo900  a closed loop is a with another L/2 "wire" connecting both ends10:39
Joerg-Neo900hetre you are
Joerg-Neo900how about this? ;-D
Joerg-Neo900note this is MW not FM band10:49
Joerg-Neo900pretty much OT but intriguing10:53
Joerg-Neo900I clearly prefer
Joerg-Neo900for N900 FMT, a 3m wire forming a circle with ~1m diameter would be ideal11:00
n00buserhey, what's the status of neo900?16:23
Joerg-Neo900~#neo900 status is
infobotJoerg-Neo900: okay16:25
n00buserhmmm, good to know16:29
Joerg-Neo900houkime still does layout, but the UG is dead16:30
Joerg-Neo900took 3 times as long as it should, and yet only 50% of needed preorders ever came in and paid only 40% of final amount each, so we reached like 70% to 90% of R&D with 25% of funds and that's it16:31
n00buserJoerg-Neo900, so if you get enough funding you will be able to finish the project?17:24

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