Radio & TV Signal Transmission System
Vertical Industry RF Popular Science: RF Components & Frequency Band Application
1. Overview of Radio & TV RF Transmission System
Radio & TV Signal Transmission System includes terrestrial wireless broadcasting, cable wired transmission, satellite broadcast forwarding, emergency public broadcast networking, compliant with national radio frequency division regulations and GY/T broadcast industry standards. Different from 50Ω universal communication RF impedance, the whole broadcast system adopts unified 75Ω standard characteristic impedance for long-distance low-loss signal transmission, divided into front-end modulation link, power amplification link, feeder transmission link, tower antenna radiation link. Broadcast RF components feature high linearity, ultra-low intermodulation distortion, high power withstand, long-term 24h uninterrupted operating performance, anti-city urban electromagnetic clutter interference, adapt to outdoor tower high-low temperature, wind-rain corrosion, urban complex electromagnetic environment. Unified broadcast station operating standard: long-term operating temperature -30℃~+75℃, outdoor tower equipment anti-icing waterproof grade IP67, whole-network harmonic distortion ≤-60dBc, 24/7 uninterrupted broadcast operating mode, urban site EMC Class 4 anti-interference level.
2. Full Standard Broadcast Frequency Band & Matching RF Components
National standardized broadcast dedicated frequency range: 87MHz–2650MHz, classified into FM audio broadcast band, VHF/UHF terrestrial digital TV band, C-band satellite forwarding broadcast band. Core dedicated impedance: 75Ω broadcast standard impedance. Conventional full-station broadcast passive RF core components: high-power broadcast cavity bandpass filter, high-isolation broadcast coaxial isolator, broadband unequal power splitter, high-linearity fixed coaxial attenuator, waterproof 75Ω broadcast dedicated RF connector, multi-channel directional coupler, trunk anti-interference bandstop filter. Two core bands are selected for targeted analysis: nationwide mature terrestrial digital television mainstream band for existing wired&wireless broadcast station, and 2026 new-generation CDR digital audio + UHD ultra-clear TV integrated forward-looking broadcast band.
3.1 Band Broadcast Application Overview
470MHz-806MHz UHF band is the national mandatory universal terrestrial digital DVB-T/DTMB broadcast frequency band, occupying over 94% market share of prefecture-level city wireless terrestrial TV, county-level main broadcast tower signal transmission, community wireless ground TV coverage system. This band features wide frequency bandwidth, large single-channel TV program capacity, strong urban building penetration, long-distance tower coverage radius, low atmospheric transmission attenuation, compatible with analog legacy TV and new digital DTMB dual-mode signal. Typical broadcast scenarios: city main tower public wireless TV coverage, county rural ground digital TV signal forwarding, campus community closed-circuit wireless TV, emergency disaster-resistant fixed broadcast signal transmission. As the core long-term operating broadcast band, UHF transmission link needs high-linear broadcast RF components to suppress inter-channel crosstalk, protect broadcast high-power transmitters, ensure full-channel ultra-clear audio-video signal fidelity transmission.
3.2 Band Power Grade & Full-station Matching RF Components
Broadcast tower link power classification: main tower continuous average transmitting power 100W-1000W, branch relay tower average power 10W-50W, instantaneous lightning surge peak power ≤1800W. Core full-station supporting components list: ①UHF high-linear broadcast cavity filter: isolate adjacent TV channel interference, purify single-program fixed frequency spectrum, avoid inter-program audio-video cross-talk; ②High-power broadcast coaxial isolator: isolate antenna tower reflected standing wave signal, prevent reflected power backflow burning broadcast solid-state transmitter; ③Broadband 75Ω unequal power splitter: realize multi-tower signal shunting, synchronous signal distribution for urban multi-point broadcast antenna; ④5dB-20dB high-power linear coaxial attenuator: adjust trunk signal amplitude, realize balanced signal coverage in urban core and suburban fringe area; ⑤IP67 waterproof 75Ω broadcast dedicated connector: anti-corrosion anti-aging, long-term outdoor tower feeder docking; ⑥Broadcast multi-channel directional coupler: real-time sampling forward/reflected power, realize remote broadcast transmitter operation monitoring. Core broadcast electrical index: system PIM≤-180dBc, channel isolation ≥45dB, trunk insertion loss ≤0.2dB/100m, port VSWR ≤1.22:1, 75Ω impedance full-link matching.
3.3 Core Broadcast Operation Pain Points Solved By Matching Components
Solved universal radio and television station operation pain points: ①Urban cellular base station, industrial frequency conversion equipment generate adjacent-frequency interference, leading to TV screen snowflake, audio noise, program frame freezing; ②Tower antenna impedance mismatch generates high standing wave reflected power, backflow damage high-cost solid-state broadcast transmitter, frequent station shutdown maintenance; ③Disordered manual signal shunting causes uneven urban signal coverage, suburban TV signal black screen; ④Common 50Ω universal communication components mismatched with 75Ω broadcast feeder, causing full-network signal reflection attenuation; ⑤Ordinary RF devices poor linearity, serious intermodulation distortion, multi-program mixed broadcast mutual interference; ⑥Outdoor common connectors rain corrosion aging, feeder signal leakage, illegal frequency signal superimposition disturbing official broadcast frequency.
4.1 Future Digital Broadcast Band Prospect
87-108MHz CDR digital audio band plus 2400MHz ultra-high definition integrated TV band is the 2026-2035 national radio and television digital upgrade core band, compliant with new national CDR digital audio broadcast standard and terrestrial 4K/8K UHD ultra-clear broadcast specification. It realizes integration of digital stereo radio, ultra-high definition TV, emergency early warning broadcast, smart community interactive broadcast integrated transmission. Compared with traditional single-function 470-806MHz UHF band, this dual combined band owns higher spectrum utilization, anti-5G base station co-frequency interference capability, embedded emergency early warning priority transmission function, supporting intelligent timing broadcast, regional precise push broadcast. New digital intelligent broadcast network puts forward higher requirements on ultra-low distortion, lightning surge resistance, multi-service isolation, intelligent frequency locking of full-link broadcast RF components.
4.2 Forward-looking Digital Broadcast Technical Bottlenecks Solved By Custom Broadcast RF Components
①Custom CDR+UHD dual-band high-linear broadcast filter: composite cavity multi-stage filtering structure, 5G urban base station co-interference suppression ≥58dB, realize broadcast and mobile communication frequency coexistence; ②Lightning-protection high-power broadcast isolator: built-in gas discharge surge protection structure, anti-lightning peak impact ≥2000W, zero outage during thunderstorm tower operation; ⑦75Ω low-distortion intelligent power splitter: temperature adaptive power balance design, full-network signal amplitude deviation ≤±0.1dB, realize urban-rural full-area equal UHD signal coverage; ④Weather-resistant low-drift broadcast coaxial attenuator: -30℃~+75℃ full temperature attenuation drift ≤±0.06dB, adapt perennial outdoor tower extreme weather; ⑤Anti-leakage shielding broadcast RF connector: double-layer copper braid shielding structure, broadcast signal leakage lower than national broadcast safety limit, prevent illegal frequency hijacking; ⑥Full-link low-intermodulation optimization: whole network intermodulation distortion ≤-65dBc, guarantee 8K ultra-clear image and lossless stereo audio transmission; ⑦Support GY/T new digital broadcast protocol, compatible old analog broadcast equipment and new intelligent broadcast host, reduce station renovation investment cost.
5. RF Engineer & Postgraduate Selection Guide
1. For conventional 470-806MHz DTMB terrestrial digital TV project, city county-level conventional broadcast tower, wired cable TV trunk transformation project, select 75Ω standard high-power linear broadcast passive components, match long-term 24h stable broadcast operation; 2. For 2026 new 87-108MHz CDR digital audio +2400MHz UHD ultra-clear intelligent broadcast station, emergency integrated early warning broadcast network renovation project, select lightning-proof low-distortion dual-band customized broadcast filter, isolator and power splitter; 3. Industry Component Summary: Broadcast RF components take 75Ω dedicated impedance as core feature, focus on high linearity, ultra-low intermodulation, lightning surge resistance, outdoor anti-corrosion anti-aging performance, completely different from 50Ω communication RF components, core guarantee components for official broadcast fidelity transmission, anti-frequency hijacking and stable network operation.
6. Radio & TV Industry Custom Inquiry Guide
We supply full-series 75Ω professional broadcast-grade RF components covering 87MHz–2650MHz full broadcast dedicated band, including linear broadcast cavity filters, lightning-proof high-power coaxial isolators, broadband broadcast power splitters, weather-resistant linear attenuators, double-shielded 75Ω broadcast connectors, multi-channel broadcast directional couplers. Support customized channel bandwidth, anti-lightning grade, intermodulation index, tower anti-corrosion shell. All products pass GY/T broadcast industry certification, outdoor IP67 weathering test, full-network intermodulation detection and 2000h uninterrupted aging test. Welcome radio and television station RF maintenance engineers, broadcast communication postgraduates, broadcast network equipment R&D engineers for sample testing, trunk link matching and long-term broadcast network supporting cooperation.