Clear One WS800 User guide

WS800 Wireless Microphone System
Antenna Application Guide
Application Guide

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ClearOne’s digital technology supports much larger microphone systems than is possible with analog
technology. It should be noted that marginal antenna designs may work well with smaller systems, but they
can cause hits and dropout as the channel counts go up. On the other hand, a well designed antenna system
delivers excellent performance with both big and small systems.
ClearOne engineers rely on following these design criteria:
Design Goal: Keep the power level of all the microphones between -40 and -60 dBm all of the time to prevent
hits and dropouts.
Design Rules:
+Rule 1: Intermodulation Distortion(1) The distance to the most distant transmitter should not be more
than double the distance to the closest transmitter.
+Rule 2: Diversity(2) The antennas should be separated so that the ends of the transmitter antenna (the
null) cannot be aimed at both antennas at the same time.
+Rule 3: Line of Sight All transmitters should remain in the line of sight of both antennas. Line of sight
means all transmitters are not blocked by metal, concrete, and similar radio opaque objects, and there is
minimal signal absorption through people’s bodies.
+Rule 4: Cable Loss The total antenna cable loss should be less than 15 dB.
+Rule 5: Range Loss Doubling the distance between a transmitter and an antenna cuts the signal
strength by a factor of 4 (inverse square law). Keep the antennas as close to the performance space as
practical without violating Rule 1.
+Rule 6: Transmitter Power(5) Adjust the transmitter power to meet the -40 to -60 dBm rating.
The following case studies show how these rules may be applied in
several common configurations:
ClearOne Extension Antennas Application Guide

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Factor Antennas In Drop Ceiling
IMD All of the transmitters are about the same distance to the closest antenna. The IMD product is small compared to the
transmitter signal. It meets the design rule.
Diversity The antennas are separated so at least one antenna is always out of the null. This meets the design rule.
Line of Sight All transmitters are in the line of sight of both antennas. This meets the design rule.
Cable Loss This configuration requires a shorter antenna run to the rack. It meets the design rule.
Range Loss All transmitters are close to at least one antenna and have about the same gain. It meets the design rule.
Transmitter
Power The setup is ideal, so set the power to 1mW for extended battery life and minimal interference with systems in near-by rooms.
Rating Expect excellent performance in all room configurations.
Factor Antennas On Back (or Front) Wall
IMD The IMD from the transmitters close to the antennas can interfere with transmitters away from the antennas. Expect drop-
out and hits with large numbers of transmitters.
Diversity The antennas are separated so at least one antenna is always out of the null. This meets the design rule.
Line of Sight All transmitters are in the line of sight of both antennas, provided the antennas are high on the wall and not blocked by
bodies. This meets the design rule.
Cable Loss Long cable runs require expensive RG8 low-loss cable but it will meet the design rule.
Range Loss Transmitters away from the antennas have approximate 3 dB less gain than the close transmitters, but it meets the design rule.
Transmitter
Power Use 10 mW output power to assure pick-up of the far transmitters.
Rating This design is prone to dropouts and hits with large numbers or transmitters.
A.
B.
1st Choice
Not Recommended
Case I:
Flexible Configurations Conference Room

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Case II:
Split Flexible Configurations Conference Room
Factor 4 Antennas In Drop Ceiling
IMD All of the transmitters are about the same distance to the closest antenna. The IMD product is small compared to the
transmitter signal. It meets the design rule.
Diversity The antennas are separated so at least one antenna is always out of the null. This meets the design rule.
Line of Sight All transmitters are in the line of sight of both antennas. It meets the design rule.
Cable Loss Antenna combiners add 3 dB loss. Make sure the total loss in each run is less than 15 dB to meet the design rule.
Range Loss All transmitters are close to at least one antenna and have about the same gain. This meets the design rule.
Transmitter
Power The setup is ideal, so set the power to 1mW for extended battery life and minimal interference with systems in near-by rooms.
Rating Expect excellent performance open or closed.
Factor 2 Antennas On Back (or Front) Wall
IMD The IMD from the transmitters close to the antennas can interfere with transmitters away from the antennas. Expect
dropout and hits.
Diversity Dividers often have metal cores which are radio opaque. Diversity is defeated when there is only one antenna in a room.
Expect dropout and hits when the room is divided.
Line of Sight No transmitter is in the line of sight of both antennas when the room is divided. It does not meet the design criterion.
Cable Loss Long cable runs require expensive RG8 low-loss cable. Make sure the loss on each side is less than 15 dB.
Range Loss Use low-loss cable for long runs. Make sure the loss on each side is less than 15 dB.
Transmitter
Power Use 10 mW output power to assure pick-up of the far transmitters.
Rating This system is prone to dropouts and hits open or closed.
1st Choice
B.
Not Recommended
A.

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Case III:
Small Auditorium or Church
Factor 2 Antennas In Drop Ceiling
IMD All of the transmitters are about the same distance to the closest antenna. The IMD product is small compared to the
transmitter signal. This meets the design rule.
Diversity The antennas are separated so at least one antenna is always out of the null. This meets the design rule.
Line of Sight All transmitters are in the line of sight of both antennas. This meets the design rule.
Cable Loss Use low loss cable to assure total loss in each run is less than 15 dB to meet the design rule.
Range Loss All transmitters are close to at least one antenna and have about the same gain to meet the design rule.
Transmitter
Power The setup is ideal, so set the power to 1mW for extended battery life and minimal interference with systems in near-by rooms.
Rating Expect excellent performance with small and large channel counts.
Factor 2 Antennas On Opposing Wall
IMD All of the transmitters are about the same distance to the closest antenna. The IMD product is small compared to the
transmitter signal. Meets the design rule.
Diversity The antennas are separated so at least one antenna is always out of the null, provided the antennas are mounted in front
of the performance space. This meets the design rule.
Line of Sight All transmitters are in the line of sight of both antennas, provided the antennas are high on the wall and not blocked by bodies.
Cable Loss Use low-loss cable to assure total loss in each run is less than 15 dB.
Range Loss All transmitters are close to the antennas. It meets the design rule.
Transmitter
Power Use 10 mW (or 25 mW) output power to assure pick-up through Presenter’s bodies and stage obstacles.
Rating Expect excellent performance with small and large channel counts.
1st Choice
B.
2nd Choice
A.

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Case III: (continued)
Small Auditorium or Church
Factor 2 Antennas On Back Wall
IMD All of the transmitters are about the same distance to the closest antenna. The IMD product is small compared to the
transmitter signal. This meets the design rule.
Diversity The antennas are separated so at least one antenna is always out of the null. This meets the design rule.
Line of Sight Place the antennas over the audience to keep the line of sight for both antennas. This meets the design rule.
Cable Loss Short antenna lengths reduce loss and cost. Use low loss cable to assure total loss in each run is less than 15 dB.
Range Loss All transmitters are far from the antennas, but within range. It meets the design rule.
Transmitter
Power Use 25 mW to overcome range loss.
Rating Expect excellent performance with small and large channel counts.
Factor 2 Antennas On Side Wall (or Rack Mounted w/ Dipoles)
IMD The IMD from the transmitters close to the antennas can interfere with transmitters away from the antennas. Expect
dropout and hits.
Diversity Diversity is defeated when the antennas are too close together. Expect dropouts when the transmitter antenna null points
at the antennas.
Line of Sight All transmitters are in the line of sight of both antennas but blocked by bodies.
Cable Loss Use low-loss cable to assure total loss in each run is less than 15 dB.
Range Loss The far transmitters have less gain than close transmitters.
Transmitter
Power Use 10 - 25 mW output power to assure pick-up of the far transmitters.
Rating This system is prone to dropouts and hits with large numbers of transmitters.
3rd Choice
D.
Not Recommended
C.

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Appendix
(1) Intermodulation Distortion Interference (IMD)
Two or more transmitters operating in close proximity produce low-level, side-band frequencies called IMD.
These sideband frequencies can interfere with other microphones that normally operate on the same side-band
frequencies, but only when the IMD signal strength is comparable to the transmitter’s signal strength. This can
happen when the interfering transmitters are in close proximity to the antennas while the interfered transmitter is
far away.
Case III - D above is a typical example. Microphones four
feet away from the antennas on stage left will have a signal
(and corresponding IMD) that is 64 times greater than the
signal from a transmitter that is 32 feet away on stage right
by the inverse-square law. In this case, the IMD signal will
cause dropouts and hits.
The science of IMD control is to arrange the antennas so
that all of the transmitters are about the same distance
away from an extension antenna. A good rule of thumb
is to divide the distance between the transmitters located
closest to an antenna and farthest from an antenna. The
result should be a number between 1 and 2. It may seem
counter-intuitive to move the antennas away from the
performance area to reduce dropouts, but Case III C will
have less IMD interference than Case III D.
In addition, ClearOne’s digital wireless transmission
method uses numerical techniques that make them far
less prone to IMD interference than is possible with analog
systems. That is one reason ClearOne’s arrays can be
much larger than is possible with analog systems.
(2) Diversity
Transmitter antennas radiate power in a toroid-shaped (donut) pattern. Very little energy radiates out the ends of
the transmitters. Separate the antennas sufficiently so at least one receives a strong signal.
(3) Dipole Antennas:
ClearOne systems are shipped with dipole (rabbit ear) antennas, but they are only recommended with small
systems and only when they are in the line of sight. They provide only a minimal diversity.
ClearOne recommends extension antennas whenever possible.
(4) Free Antenna Design:
ClearOne offers complete antenna hardware kits custom made for your project. The kits include extension
antennas, tested antenna cables with proper terminations, and antenna combiners if required. The goal of
extension antenna kits is to take all of the guesswork out of one of the most challenging and critical aspects of a
wireless microphone installation so your job is completed on time and within budget.

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(5) RF Scan: Antenna Power Measument
Run the ClearOne Remote software RF Scanner to verify the antennas and cables are working correctly. Each
transmitter is represented by two green lines, one for each antenna. The received power from at least one
antenna should always be between -40 and -60 dBm.
(6) Built-in antenna distribution
Daisy-chain up to 32 channels and connect to a pair of extension antennas

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Antenna Mounting Instructions
NOTE:
wall-mounting
screws not supplied
Use the L-connector to route the cable through the back plate.
Screw the plate to the wall or lay the antenna on a drop ceiling.
Press on the plastic case cover.
NOTES:
Paint: The plastic case can be painted with non-metalic paint to match the decor.
Outdoor Mounting: ClearOne extension antennas are designed for outdoor use, but they
operate normally mounted inside a waterproof plastic box.
Polar Pattern: ClearOne extension antennas have a 160 degree polar pattern. Ceiling mounted
antennas typically cover the entire room.
1
2
3
4
5
6
7
Gently pull the plastic exterior case from the rest of the antenna
assembly. It is a press fit.
Unscrew and discard the black microphone-stand mount from the
antenna assembly.
Connect the antenna cable to the TNC connector.
or

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Mounting Instructions for Mic Stands
Microphone Stand Mounting
Position antennas according to the rules in the case studies
above. Do not daisy-chain extension antennas together in series.
1
2
3
4
Thread the antenna onto the mic stand.
Gently pry the exterior case from the rest of the antenna assembly.
Attach antenna cable to TNC connector on the antenna
assembly. Hand tighten only. Reattach the exterior case.

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Extension Antenna Cables
Government regulations severely limit the output power of wireless microphones. For a comparison, mobile
phones connect to towers miles away, but wireless microphones barely reach 300 feet line-of-sight. A mobile
phone is similar to a lighthouse that shines to the horizon, while a wireless microphone is like a penlight that
barely casts a shadow on the far side of a dark auditorium. Microphone power limitations make extension anten-
nas systems a critical component of every wireless microphone system, and coax cables are a critical part of
every antenna system. There is no room for error.
ClearOne provides antenna kits that includes the extension antennas and the cables. The cables are cut to
length, properly terminated, and individually tested at ClearOne operating frequencies. ClearOne also provides
extension antennas without cables, but it should be noted that we have found serious errors in the spec sheets
published by two of the industry’s largest and best know cable suppliers. Had our clients purchased and in-
stalled these cables, their microphone systems would have never worked properly, and the antenna cables may
have never been identified as the cause.
Plenum Rated Cables have a special coating (usually Teflon) that does not give off toxic gasses and smoke when
it burns. Some building codes require plenum-rated cables, but longer plenum cables are considerably more
expensive than standard cables. Kits with longer cables are available with plenum or standard cables.
ClearOne systems require 50 Ohm Coax Cable with a total line loss
less than 15 dB at 900 MHz.
ClearOne Part
Number Product Description Length (Ft)
Fire Rat-
ing Diameter (in) Nom loss at 900 MHz (dB)
910-6005-001
WS-EAK25-M915: Extension Antenna kit
with pair of antennas and 25Ft RG58 Plenum
cables tuned for Radio Frequency band M915
(902-928 MHz)
25 Plenum 0.158 5
910-6005-002
WS-EAK25-M715: Extension Antenna kit
with pair of antennas and 25Ft RG58 Plenum
cables tuned for Radio Frequency band M715
(710-740 MHz)
25 Plenum 0.158 5
910-6005-003
WS-EAK25-M610: Extension Antenna kit
with pair of antennas and 25Ft RG58 Plenum
cables tuned for Radio Frequency band M610
(603-630 MHz)
25 Plenum 0.158 5
910-6005-011
WS-EAK50-M915: Extension Antenna kit
with pair of antennas and 50Ft RG58 Plenum
cables tuned for Radio Frequency band M915
(902-928 MHz)
50 Plenum 0.158 9
910-6005-012
WS-EAK50-M715: Extension Antenna kit
with pair of antennas and 50Ft RG58 Plenum
cables tuned for Radio Frequency band M715
(710-740 MHz)
50 Plenum 0.158 9
910-6005-013
WS-EAK50-M610: Extension Antenna kit
with pair of antennas and 50Ft RG58 Plenum
cables tuned for Radio Frequency band M610
(603-630 MHz)
50 Plenum 0.158 9
North America
Tel: [phone]
Toll Free: 800-945-7730
Sales: 800-707-6994
Fax: [phone]
[email protected]
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Other product names may be registered trademarks of their respective owners who do not necessarily endorse ClearOne or ClearOne’s products. All rights reserved. Information in
this document subject to change without notice. © 2012 ClearOne. DOC-0082-001 Revision 1.0 December 2012.