How headphones work as an Antenna to play FM radio channels on Mobile phones? Why mobile companies doesn't install the same inbuilt Antenna on phones to be able to play FM without the headphones?

To understand how headphones function as an antenna for FM radio on mobile phones and why mobile companies do not install built-in antennas, here are the key points:

Headphones as an Antenna

• Headphones act as an effective antenna for FM radio signals because their length is approximately half the wavelength of FM broadcast signals (which is around 3 meters for the FM band of 88-108 MHz). A typical headphone cable is about 1-1.5 meters long, making it resonant and effective for picking up FM signals134.
• The headphone cable, along with some passive components like inductors and capacitors, allows the RF (radio frequency) signals to pass through to the receiver while blocking the audio signals from interfering with the antenna input. This setup enables the phone to use the headphone cable as an antenna1.

Why Mobile Companies Do Not Install Built-in Antennas

• Mobile phones do not have built-in FM antennas primarily because it would add bulk and weight to the device. Integrating a dedicated antenna for FM radio would make the phone less appealing and more cumbersome3.
• Modern smartphones are designed to be compact and multifunctional, prioritizing features like internet connectivity, computing power, and communication over traditional radio reception. Including a built-in FM antenna would compromise these design goals23.
• Using headphones as an antenna provides a convenient workaround without the need for additional hardware within the phone. Since many users already use headphones for listening to music, this solution leverages existing components to enable FM radio functionality13.

Alternative Solutions

• For users who do not have access to FM radio through their phone's built-in capabilities or prefer not to use headphones, there are alternative methods such as streaming FM radio stations online through the phone's internet connection2.
• Some users have also created DIY antennas using old headphones or other materials to improve FM radio reception without relying on the phone's headphone jack5.