"lsmyer" kirjoitti viestissä
...
I enjoy AM dxing, and I've noticed that the radios with larger ferrite
rods
seem to be better for dxing than those with small ones.
I did some research on the subject, and I kept running into terms such
q-factor and flux. My 45-year-old mind only has room for so much, and I'm
afraid that anything I try to learn about electronic theory will just push
out some of the more important stuff already stored in there such as
anniversary dates and current wife's name.

So maybe somebody can answer a couple of questions for me in simple
English,
and maybe help me save what few brain cells I still have left.

1) Is there an optimal length for an internal ferrite antenna?
2) If so, then why don't all radios have one that size?
3) Is ferrite expensive or something?
4) How can my little Degen 1102 (tiny ferrite antenna) do so well on MW
while my ATS505 does so poorly?

Thank you in advance for all who reply.


All the receivers have a limited space for the ferrite antenna. I am no
expert in antennas, but what little I know is that

1) The total physical length of an antenna (ref: wavelength) is important:
usually the longer the better
2) The tuning of the antenna is important, too. Is the antenna "fitted"
to the "front end" of the receiver and how well... e.t.c. ?
If a receiver is "tuned" to work fine on shortwave it may not work
fine on MW
3) Ferrite itself is not expensive, though the retail price for a piece
of antenna can be high
4) My little Kenwood TH-F7 is more sensitive with its tiny
ferrite rod and my old Grundig YB207 is not with its longer
piece of ferrite. Kenwood, though, is too sensitive for all
kind of noise and "parasites", too.

73's, Matti Ponkamo, Naantali, Finland