![]() Modern receivers weather multi-path propagation storms well, due to superior sensitivity and intelligent diversity switching circuits, but even the best receivers obey laws of physics and information theory, and will suffer frequent dropouts if line-of-sight is absent, regardless of how much they cost. The probability of a multi-path dropout (when two waves of similar amplitude arrive at a receiver 180 degrees out of phase) is much greater when the receiving antennas of a diversity system are presented with multiple reflected waves of similar amplitudes, versus between one strong, primary line-of-sight wave and comparatively weak reflected waves. Multi-path waves carry signal containing the same audio information, but, because they have been absorbed and re-radiated several times by RF reflective materials within a building or outdoor venue, are weaker in amplitude than a line-of-sight wave. Usually this signal is a multi-path wave from the same transmitter-the performer's radio microphone transmitter, or rack-mounted IEM transmitter-that has "reflected" across walls and other materials (and traveled multiple paths) at locations other than the line-of-sight destination. The receiving antenna momentarily loses contact with the signal carried by the line-of-sight radio wave, and the receiver grabs hold of the next strongest signal on its tuned frequency. Even with good placement, performers' movements inevitably bring bodies or scenery between antennas for one or more brief intervals. It is not always possible to maintain line-of-sight indefinitely. It is essential that antennas of all kinds are deployed to maintain line-of-sight between performers and rack equipment in a configuration that minimizes interruptions to the line. In radio terminology for entertainment production, line-of-sight refers to radio waves traveling straight and across an unobstructed path between receiver antenna and transmitter antenna. For more information, please see his bio at the end of this post. The following post on wireless audio antenna placement is a guest contribution from Alex Milne of RF Venue, Inc - a US based manufacturer of innovative products that make wireless audio systems work and sound better. Guest contributor Alex Milne of RF Venue, Inc talks about the 5 rules for wireless audio antenna placement. Condividi Five Golden Rules for Wireless Audio Antenna Placement ![]()
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