Frequency modulation and antenna size

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SUMMARY

The discussion centers on the relationship between frequency modulation (FM) and antenna size, specifically addressing how varying carrier frequencies affect antenna dimensions. It is established that antenna size should be approximately one-half of the wavelength of the carrier signal, contradicting the initial claim of one-tenth. The complexity increases with frequency shift keying (FSK), where multiple frequency levels necessitate a broader bandwidth for antennas. The use of patch antennas is highlighted as a solution, as they can accommodate a range of frequencies required for FSK modulation.

PREREQUISITES
  • Understanding of frequency modulation (FM) principles
  • Knowledge of frequency shift keying (FSK) techniques
  • Familiarity with antenna design and dimensions
  • Basic concepts of bandwidth in communication systems
NEXT STEPS
  • Research antenna bandwidth requirements for frequency shift keying (FSK)
  • Explore patch antenna design and its applications in mobile devices
  • Study the principles of resonant antennas and their wavelength relationships
  • Investigate advanced modulation techniques and their impact on antenna design
USEFUL FOR

Engineers, telecommunications professionals, and students studying radio frequency (RF) communications who are interested in antenna design and modulation techniques.

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We know to make antenna dimension reasonably small, we modulate baseband signal with a high frequency carrier. Antenna size as far as I know is in the order of one tenth of carrier signal wavelength. For example, for a 3 GHz carrier signal, receiver antanna size is 1 cm.
But, in frequency modulation, carrier frequency varies according to the baseband signal. As the antenna size depends upon carrier wavelenth, antenna size also varies! It implies we have to appoint several antennas of different sizes to receive frequency modulated carrirer signal!

Situation becomes puzzling to me when we use FSK (frequency shift keying). Digital baseband signal may have 32 (or more) levels implying 32 diffrent changes in the frequency of the carrier.Hence we need 32 different size antennas to receive the same FSK carrier signal.
How do we resolve this strange issue? Or is it I'm missing any point?
Thanks in advance.
 
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Real antennas have a certain bandwidth, meaning they are usefull of over a range (band) of frequencies. Patch antennas and similar -often used in handheld devices- are designed to have a bandwidth wide enoiugh so that they cover the whole band needed for modulation schemes such as FSK.
 
...And resonant antenna length is 1/2 of a wavelength (for a dipole), not 1/10 of a wavelength.
 

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