Speaker (coil)...usable as antenna ?

[watchjohn]

.

For my wristwatch-sized bugdetector i need lots
of antennas on a very small space.

Since i have a speaker in there also
i wonder if i could use that as antenna
for the lower part of (HF)frequencies...allthough
it would be nice if it went up to 100 Mhz

I have not decided on wich speaker yet
But probably it´s going to be 8 Ohms,200 mW
In a plastic housing...the coil and the connections
are the only metal parts...one of these for example:

http://www.elproma.com/buzzercat/buzzer-5.html

I will have more(other) antennas for the other freq-bands.


Question 1
----------

For wich freq-range could i use such speaker (coil)
It will not be tuned with a capacitor since i have to
detect a broad-range of frequencies.
Normally i would say it will only do the lower HF frequencies (shortwave)


Question 2
----------

What to look for in a speaker for antenna purposes ?
wich one from the mentioned link might serve ? why ?


Question 3
----------

I suppose the directivity/pattern will be the same as
the sound direction...something like an 8 characteristic
what can i do to make it only look outwards
...in one direction ?


Question 4
----------

Since the speaker when also used as antenna will have
a dual function...will i have some feedback-problems ?
meaning that the received audio will make the coil
vibrate..and therefore cause feedback/oscillations ?
Simply block that with a Highpass LC-filter ?


Questions 5
-----------

Anyone have a link to an example where they
use a speaker as antenna...(no show on Google)
Or suggestions for the circuit at the speaker ?


Thanks again !


WatchJohn

 

[Higgler]

Interesting idea since it's already got a ferrite in it and alot of wire.
If you have some way to test it (network analyzer), you'd find your answer quicker than research and analysis.

kch