Antenna Detuning Effects on Transmitter Power Amplifier Efficiency
Antenna detuning shifts transmitter power amplifier load impedance away from nominal conjugate match, slashing power added efficiency and draining battery reserves.
Transmission Line Loss
Meaning
RF power degradation along physical conductor paths measures signal attenuation between an output amplifier and an antenna feed point. On printed circuit boards, transmission line loss accumulates from conductor skin effect, substrate dielectric absorption, and radiation leakage along microstrip or stripline traces. System link budgets account for this power loss when calculating total radiated power and receiver sensitivity.
Attenuation metrics no longer follow linear models when high power levels cause thermal substrate degradation.
Conduction Attenuation
High-frequency currents concentrate near the outer surface of metallic conductors, reducing effective cross-sectional area and elevating series resistance. Smooth conductor surface finishes minimize skin effect losses at millimeter-wave frequencies. Copper foil profile selection dictates total trace resistance on high-speed circuit boards.
Dielectric Absorption
Alternating electric fields dissipate power as heat within insulating board substrates separating signal traces from ground planes. Substrate loss tangent values govern the rate of energy dissipation per unit length. Selecting low-loss fluoropolymer or hydrocarbon laminate materials reduces dielectric attenuation in sub-gigahertz and microwave designs.
Signal Decay
Total signal attenuation scales directly with physical trace length across modern printed circuit board layouts. High-frequency signals lose amplitude as they propagate from RF transceivers to remote antenna connectors. System designers minimize trace routing distances to preserve receiver noise figure performance.