21 vastust kokku ei tulnud, aga räägi see müütiline saladus välja
elektro- ja raadiotehnilisest teooriast lähtuvalt.
Palun räägi
"common mode current",
"common mode noise" lihtsas keeles lahti ja mis nende eestikeelsed terminid on.
Minu vastus on, et selle saladuse teadasaamine võib aidata müradest lahti saada isegi siis kui tegu pole täislaine pikkuse loop antenniga.
Antenni polarisatsiooni, kõrguse maapinnast, tõusunurgad, mürade levimise skeemid ionosfääris ja polarisatsiooni jätan ma mängust välja.
Ma julgen väita, et lühilaine peal vähemalt 1/2 lainepikkuse kõrgusel 2-elementi yagi püüab vähem müra kui vertikaalselt polariseeritud
monoband delta loop.
Common mode antenna input impedance
The (conducted) common mode input impedance of an antenna is derived from treating the antenna as a single‑wire transmission line in common mode.
In common mode, the legs of a half‑wave center‑fed dipole can be seen as a quarter‑wave long single‑wire transmission line. This transmission line is open at the end and transforms this over its quarter‑wave length to a low common mode input impedance at the feed point.
On the other hand, a full‑wave loop antenna behaves as a half‑wave long single‑wire transmission line in common mode, but with an open at its end. This transforms to a high common mode input impedance at the feed point. This explains why full‑wave antennas are less susceptible to receiving common mode noise.
The common‑mode input impedance of a folded half‑wave dipole is equally high for the very same reason. Even more interestingly, folded half‑wave dipoles can easily be made self‑balancing.
https://hamwaves.com/chokes/en/index.html
