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Our Guide to AKG Antenna Systems
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Our Guide to AKG Antenna Systems

When specifying for wireless microphone systems one of the key components (other than the receivers and mics… obviously) is the antenna system. It’s key that you get a clean, uninterrupted signal throughout your event and without proper distribution with the correct equipment that becomes increasingly less likely.

During this blog, we will be looking at the principles of antenna distribution and the products from AKG that can enhance your wireless solution. So let's start with what we consider the most important rule to make sure that you get the performance you need.

Antenna placement is KEY. It seems pretty common sense, but so often we see whip antennas buried at the back of AV racks causing issues. It is important that you get your antennas in the correct position and ideally this is with a line of sight from antenna to transmitter. That can be pretty tricky in large spaces, and that’s where appropriate distribution and external antenna choice comes in.


Lets take the example of a church install where coverage was fine when the congregation was seated, but as soon as everyone stood there were drop outs. The antennas has been located on mic stands next to the sound guy sitting at the back (seems sensible right?), but they were positioned so low that as soon as everybody stands up the RF signal has to travel through the whole congregation and we get drop outs. Raise the antennas up above standing height and we get a line of sight and resolve the issue.


  • Main pointers for antenna/receiver placement would be:
  • Direct line of sight between antenna and transmitter
  • Keep the receiver/antennas at least 1.5m away from all transmitters
  • Keep the receiver/antennas at least 1.5m away from big metal objects, wire mesh or sheet metal structures, walls, ceilings etc. (Google faraday cage if you want to know a bit more on the why of it!)
  • Do not place antennas in closed spaces (behind walls, at the back of AV cabinets…)
  • Place the receiver at least 1.5m away from any equipment that may emit RF radiation such as lighting racks, fluorescent lamps, digital effect units and PC’s.


Obviously, this is a wishlist and isn’t always possible in the venue, but by trying to meet the above you are setting yourself up for success.

Now we have the ‘rules’ out of the way, let's look at AKG’s solutions. 

Antennas


¼ wave antennas (commonly called whip antennas) come as standard with most AKG wireless systems. These fit directly onto the receiver or in some systems can be mounted to the front of the rack using a short extension cable and a special rack plate. For single receivers in small spaces (conference rooms) these work well and allow the unit to function as a stand alone box. But for larger applications, or instances with multiple receivers you ideally want larger external antenna and distribution. 


SRA2EW 


The SRA2 EW is a passive directional wide-band UHF antenna that can be used as a transmitting or receiving antenna for wireless microphones and in-ear monitoring systems. A directional antenna gets used when you know the focal pickup point (such as a stage) that you need to aim the antenna towards for pickup. Coverage can be up to 150m with this particular antenna. It operates in a frequency range from 470MHz to 952MHz and provides a covering angle of 70° and an antenna gain of 6dB. The SRA2 EW is passive and requires no powering. It works for short cable lengths up to 10m and supports a professional BNC connector.

The antenna is also waterproof so is suitable for indoor and outdoor applications.


RA4000B/EW and RA4000EW 


The RA4000 series antennas are passive omnidirectional antennas commonly used when there is no designated transmitter area and broad coverage is needed. Ideal for office spaces, conference halls, multi-purpose venues, houses of worship etc. With a coverage range of upto 100m. We often see them mounted onto ceiling tiles to offer a good high line of site.

The RA4000 B/EW is an active omnidirectional wide-band UHF receiving antenna. It operates in a frequency range from 470MHz to 952MHz, providing a covering angle of 360° and a total gain of 18dB. The RA4000 B/EW has a built-in amplifier to compensate for long cable runs. With dedicated antenna components, it works for cable lengths up to 300m. The RA4000 B/EW is remotely powered through the antenna cable.

The antenna is waterproof so can be used for indoor and outdoor applications.  

The RA40000EW is the passive version of the RA4000B/EW it has a total gain of 1dB, due to its passive design it does not include an amplifier so is designed for shorter cable runs of up to 10m.

APS4 


The APS4 is a wide-band UHF active Antenna and Power Splitter that can feed up to 4 receivers with the RF signal coming from one pair of antennas. Essentially this box takes your two antennas in and spits them out to four attached receivers. There is a 5th output that is used to feed additional APS4 units which can be cascaded for large distributed antenna setups. The splitter operates in an extended frequency range of 470 to 952 MHz. Adjustable RF-level attenuation settings guarantee maximum operating distance even when using different cable lengths and different types of cables. The APS4 works with all active and passive AKG antennas. Two rear panel antenna inputs provide a 12 VDC supply voltage for powering up to three active elements per antenna path, this can be boosters or active antennas.


Behind the AKG logo are the RF level attenuation dip switches (AKA the cable length attenuators). These switches reduce the input RF level to the antenna input. To obtain the best sound possible, you need to have the correct RF input level throughout your signal chain. Premium quality wireless systems offer you adjustable RF-level settings that guarantee to maximize operating distance even when mixing and matching different cable types and lengths. 


AB4000EW


When using longer cable lengths and larger channel counts we can also supply in-line antenna boosters in the form of the AB4000EW.


AB4000 High-performance antenna booster for inserting into long antenna cables. One AB 4000 can compensate for approx. 17 dB of cable attenuation, allowing RG 213 cable runs to be extended by approx. 75m. Up to two AB 4000 boosters can be used in series for extremely long cable runs.


ASU4000


The ASU4000 is an in-line power booster which supplies additional power for up to three active elements (e.g. RA4000BW, SRA2BW, AB4000). This allows for larger distributed systems than just the APS4 can handle.


ZAPD21 2-1 combiner


The ZAPD21 is a third party splitter/combiner for BNC aerial systems and is what AKG recommends for larger systems. These can be used to combine multiple aerials (for coverage of large areas) and for duplicating/splitting these signals to multiple recievers.



Here is an example of a heavy channel count system with multiple antenna locations and boosters used for extra long cable runs.


Other points to remember when designing a wireless systems are:


  • Every wireless microphone HAS to operate on its own discreet frequency, any crossover between mics can cause interference
  • The transmitter (mic or beltpack) and receiver of a system need to work on the SAME frequency
  • Two transmitters cannot be used with the same frequency at the same time
  • For long cable runs you should use RG213 cable and calculate cable. This can then be configured by the dip switches on the front of the APS4. (There is an useful table on page 27 of the APS4 user manual).

Hopefully, this article has given you some useful insight into designing an antenna system for wireless microphones and given a good grounding in the products available from AKG with which to do this.


For any additional information or design assistance for the AKG wireless range please do not hesitate to contact our Application team here at Sound Technology.