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Null Fill Information

Null fill is used in radio antenna systems which are located on mountains or tall towers, to prevent too much of the signal from overshooting the nearest part of intended coverage area. Phasing is used between antenna elements to take power away from the main lobe and electrically direct more of it at a more downward angle in the vertical plane. This requires a phased array. Changing the relative power supplied to each element also changes the radiation pattern in this manner, and often both methods are used in combination.

References

See also

Analogue television broadcasting topics
Systems 180-line • 405-line (System A) • 441-line • System B (also G and H) • System M • 819-line (System E)
Color systems NTSC • PAL • PAL-M • PAL-S • PALplus • SECAM
Video Back porch and front porch • Black level • Chrominance • Chrominance subcarrier • Colorburst • Color killer • Color TV • Composite video • Frame (video) • Horizontal scan rate • Horizontal blanking interval • Luma • Nominal analogue blanking • Overscan • Raster scan • Safe area • Television lines • Vertical blanking interval • White clipper
Sound Multichannel television sound • NICAM • Sound-in-Syncs • Zweikanalton
Modulation Frequency modulation • Quadrature amplitude modulation • Vestigial sideband modulation (VSB)
Transmission Amplifiers • Antenna (radio) • Cavity amplifier • Differential gain • Differential phase • Diplexer • Dipole antenna • Dummy load • Frequency mixer • Intercarrier method • Intermediate frequency • Output power of an analog TV transmitter • Pre-emphasis • Residual carrier • Split sound system • Superheterodyne transmitter • Television receive-only • Television transmitter • Terrestrial television • Transmitter station • Transposer
Frequencies & Bands Frequency offset • Microwave transmission • Television channel frequencies • UHF • VHF
Propagation Beam tilt • Distortion • Earth bulge • Field strength in free space • Knife-edge effect • Noise (electronics) • Null fill • Path loss • Radiation pattern • Skew • Television interference
Testing Distortionmeter • Field strength meter • Vectorscope • VIT signals • Zero reference pulse
Artifacts Dot crawl • Ghosting • Hanover bars • Sparklies

Categories:

 

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