Hi. Frequently, read that antennas are generally as good for receiving as they are for transmitting.

Plain AM radio receivers (300m band / 1MHz) use mostly ferrite rods with a wound coil as antenna for reception, that gets nearby stations during the day and can receive long distances at night (skip).

Part 1 : Transmitting with that antenna... What to expect ? A 1MHz oscillator, fed to such 'loopstick' coil... Would it radiate ?

Part 2 : Winding a 'beefy' coil - thick wire on a ferrite rod... brought to resonance with proper capacitance... Feeding 1MHz -say 1 Watt- . What to expect in range ?

Part 3 : Pulling the ferrite rod core out of coil, replacing with an iron core rod (laminated or not)... Would it have longer or shorter transmission range ?

 

1. The radiation resistance for that type of magnetic loop transmit antenna is usually low and the usual RF Ferrite material properties degrade quickly with power causing poor transmit efficiency.
2. No real improvement in efficiency due to the wire.
3. That would turn the rod antenna into a resistor because of the iron core flux and eddy current losses.

 

Thank you.
What can be done to the coil to raise the radiation resistance ? More turns ? Thinner wire ?

 

Thank you.
What can be done to the coil to raise the radiation resistance ? More turns ? Thinner wire ?

https://www.st-andrews.ac.uk/~jcgl/Scots_Guide/RadCom/part7/page5.html
https://www.st-andrews.ac.uk/~jcgl/Scots_Guide/RadCom/part6/page4.html

For a small loop (or just about any type) antenna the only thing you can do is to make it larger because radiation resistance mainly depends on geometry (EM wave phase difference across physical free space vs the electrical "shorter" size of the antenna at the frequency) of the antenna with the 'best' loop being a single loop cut and tuned to the correct frequency.

 

Here's an article that explains why ferrite makes a good receive but a poor transmit antenna.