- #1
David lopez
- 257
- 3
if an antenna 8.2 feet long was coiled up into a coil could it still receive radio signals at 30 megahertz?
Sure. I can receive those signals with my tooth fillings.David lopez said:if an antenna 8.2 feet long was coiled up into a coil could it still receive radio signals at 30 megahertz?
i usedberkeman said:Sure. I can receive those signals with my tooth fillings.
Can you post the antenna equations that apply to your question please?
so it won't receive a signal, because the resistance of the copper wire will absorb most of the energy?tech99 said:The small antenna has very small radiation resistance - in other words, it does not couiple verty well to the incoming wave. If we can extract all the power from this small resistance, fine, but the resistance of the copper wire is large by comparison and will absorb most of the energy.
Hmmm.David lopez said:i used
so it won't receive a radio signal, because the resistance of the copper absorbs most of the energy?tech99 said:The small antenna has very small radiation resistance - in other words, it does not couiple verty well to the incoming wave. If we can extract all the power from this small resistance, fine, but the resistance of the copper wire is large by comparison and will absorb most of the energy.
Yes. Let me talk about a transmitting antenna because it is easier to explain. When we reduce the size of the antenna, the radiation resistance reduces very drastically. Provided we can couple all our transmitter power into that small resistance, we still have good radiation. But the problem is that the loss resistance of the antenna now becomes significant and absorbs power.David lopez said:i used
so it won't receive a signal, because the resistance of the copper wire will absorb most of the energy?
I think the OP is asking about an Rx antenna, but I could be wrong...David lopez said:if an antenna 8.2 feet long was coiled up into a coil could it still receive radio signals at 30 megahertz?
David lopez said:if an antenna 8.2 feet long was coiled up into a coil could it still receive radio signals at 30 megahertz?
so how do you receive 30 mhz signals with an electrically small antenna?berkeman said:And after reading that other thread that I linked, can you say more about why Rx and Tx can use different antenna structures?
What is your application? You want to receive 30MHz transmissions with an electrically small antenna? That's pretty easy, if that's what you want to do.
David lopez said:see i read the other thread.
David lopez said:does this mean a 3 foot long antenna could pick up 30 megahertz signals?
David lopez said:a device that will measure the temperature in my home, when i am not home, has to be when i am not home, and sent a message over long distance, which is why i use 30 megahertz.
David lopez said:a device that will measure the temperature in my home, when i am not home, has to be when i am not home, and sent a message over long distance, which is why i use 30 megahertz.
There are no unlicensed bands around 30MHz near your location that I'm aware of, especially not allowing enough power to make the transmission that you are trying to do. What licensed band are you planning on using, and what is the FCC callsign that you have been assigned/purchased?David lopez said:could you still answer this question?
A high frequency antenna is a type of antenna that is designed to operate at frequencies above 30 MHz. These frequencies are typically used for communication and broadcasting purposes.
A high frequency antenna is designed specifically to operate at higher frequencies, whereas other types of antennas may be designed for lower frequencies. High frequency antennas also tend to be smaller in size and have a narrower bandwidth compared to other antennas.
Some important factors to consider when designing a high frequency antenna include the desired frequency range, the type of signal being transmitted or received, the antenna's gain and radiation pattern, and the materials used in construction.
Some common types of high frequency antennas include dipole antennas, loop antennas, Yagi antennas, and parabolic antennas. Each type has its own unique characteristics and is suited for different applications.
Designing a high frequency antenna can be challenging due to the small size and high frequency of operation. This requires careful consideration of materials, construction techniques, and other factors to ensure optimal performance. Additionally, high frequency antennas may be more susceptible to interference and noise, so shielding and filtering techniques may need to be incorporated into the design.