What is Antenna Distribution and when should you use it?

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AV, Live  |  28/10/2015  |  By Tom Colman  |  Add Comment

antenna-distribution

Tom Colman from Shure UK’s Systems Group gives a concise description of Antenna Distribution and its practical use with wireless microphone systems.

A question that comes up quite frequently is the subject of antenna distribution and what is it used for? In simple terms, it is a way of getting two discreet antenna feeds to individual received channels.

After spending thousands of pounds on several channels of wireless microphones, proper antenna distribution is an essential accessory. Yes it is an extra cost, but if you are using more than one wireless system it really should be a serious consideration in order to achieve optimal performance of your system.

In the example below you will see that antenna A and B are split four ways four into four receivers by using an antenna distribution unit.

diagram-4way

What happens if we have more than four receivers? In the example below we need a different type of antenna distribution that involves cascading RF from the first antenna distribution unit into the second. This cascading allows us to feed more receivers, subsequently, from the main antenna feed.

diagram-8way

Cascading can be quite complex in larger systems where more receivers and antennas are needed. The example bellow shows 12 receivers: one main distro, three sub distros with the antennas providing RF to each distro individually, which subsequently sends RF down to another set of receivers. As you can see, there is still a spare output on the main antenna on top that allows for expansion of a further set of four receivers (16 in total).

diagram-12way

Passive vs. Active Splitters
Passive splitters should only be used for two wireless systems or less. These systems are limiting because 3db of signal is lost every time the signal is split. Passive splitters are sufficient for applications that only require a short range, however if you are relying on long range pick up an active splitter is needed. Active splitters will feed up to five receivers and multiple active splitters can be combined to form larger systems.

RF Cascade
Certain antenna receivers offer  outputs on the rear of the unit that offer the ability to cascade the antenna signals from one receiver to the next, for up to 10 units simultaneously (although we suggest limiting it to five receivers maximum as a best practice guide). As the RF Cascade circuitry is active, there are limitations to this method. For example, if power is lost to the 3rd receiver in the cascade, the 4th and 5th receivers in the chain will lose RF signal as well.

This content is an excerpt from Shure UK’s Wireless Mastered: Installed seminar. Click here to join our mailing list and receive notifications about future Shure Academy events. You will also receive a free download of the Shure Wireless Microphone Configurator.