How Do UHF Antennas Work?
UHF antennas (ultra-high frequency antennas) act as "converters" for
electromagnetic signals in the ultra-high frequency band (300MHz-3GHz). Through
precisely designed conductive structures, they enable the reception and
transmission of signals, with their core principle centered on electromagnetic
induction and energy conversion.
The Process of Receiving Signals:
When radio waves in the UHF band (composed of mutually perpendicular
electric and magnetic fields) exist in space, the metal conductors of the
antenna (such as dipoles, patches, etc.) generate induced currents due to the
cutting of electromagnetic waves. This utilizes the law of electromagnetic
induction, converting invisible electromagnetic waves into transmissible
electrical signals. The length and arrangement of the conductors are optimized
to resonate at the target frequency, similar to "tuning" to a specific
frequency, thereby efficiently capturing weak signals and reducing interference
from irrelevant frequency bands.
The Process of Transmitting Signals:
Transmission operates in reverse: electrical signals (carrying voice, data,
etc.) output by the device are fed into the antenna. As the electrical signals
flow through the conductors, they induce alternating electromagnetic fields
around them. These fields radiate into space as electromagnetic waves,
completing the conversion from electrical energy to electromagnetic energy.
Key Design Factors:
Directionality: By adjusting conductor layouts (such as directors and
reflectors in Yagi antennas), signals can be focused (directional antennas) or
omnidirectionally covered (omnidirectional antennas) to meet different scenario
requirements;
Impedance matching: Ensures consistent impedance between the antenna and
the device to avoid energy loss caused by signal reflection;
Polarization: Including vertical polarization, horizontal polarization,
etc., which must match the transmitting end to maximize signal reception
efficiency.
From broadcast television to 5G communication, UHF antennas, through
precise control of electromagnetic signals, serve as the core hub of wireless
transmission.
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