Shark Fin Antenna Set up

C

Cedric Akins

Well-known member
I have a question. I am in the process of purchasing multiple wireless mics. I am considering adding a shark fin antenna to help decrease signal dropout. I have never used one before and wondered how they worked. I have looked on youtube to see if I could locate some footage on using this type of set up, but no video exists. How many, if any, of you pro audio guys have used these? What do you need to set this type of system up? Would just any wireless mics work with this type of set up? Sennheiser G2/G3 wireless mics... Any feedback would be appreciated.

Thanks.
 
Generally, you'll have an active antenna distributor as part of your rack system. The shark fins will connect to the distributor, which will feed your wireless receivers.

For Sennheiser, look at the ASA 1. It is not compatible with the ENG receivers, but is designed to work with the rack-mount rceivers. It will support up to four separate receivers.
 
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Position the antenna in an inward facing XY set up it gives better coverage than an outward facing set up. The pickup pattern is similar to a short shotgun microphone but in RF rather than audio.

Keep the antenna at least one wave (can be more) length apart (600mhz = .5m)

Position one antenna one wave length higher than the other.

Position them slightly off vertical (approx 30deg) in different directions, this allows for position variations on Tx units.

These have been my personal observations of Lectrosonics, Shure and Sennheiser systems used for TV broadcasting.
 
Well that pretty much answers that. Like i said, I've never used an external antenna before. So now I know it won't work with the wireless mics I have.
 
Thank you both for your responses. If I decide to get rack mountable recievers then the external antennas will be the go to for on set audio.
 
Cedric Akins said:
If I decide to get rack mountable recievers then the external antennas will be the go to for on set audio.
Click to expand...

You can purchase the rackmount receivers by themselves since you already have transmitters, as long as you get them in the same band. Then you have the flexibility to bounce between bag work and cart work.
 
I agree with the above and the shark-fin antennas work great.. if you have the necessary components.
However many of the portable receivers have no way to connect them with their hard wired antennas, such as the Sennheiser EK100 portable receiver. Most base station receivers would work as would most portables with BNC connectors like the Lectro 211/411.
 
Your dropouts may have more to do with interference than antennas. How do you know your frequencies are clear? That is the first consideration. Does your system have a method of scanning for clear white space? The only way to know for certain is to use some type of sweep scanner. I use one at work and I can see graphically exactly what is happening.
There are some web applications that might help too. Input your location and they provide information on registered transmitters in the area. Sorry I can't be more specific. I have no personal experience but some of my associates do.
Also check out Kaltman CP antennas that are designed for use with body packs. Always use short as possible 50 ohm cable with no (adapters or barrels) breaks. Max length RG58 is about 15 feet after that you need to use RG6. Some antennas have built in amplifiers to over come dB loss in longer cable runs, but you receiver needs to support that.
Sombody mentioned using different receivers. Only use receivers designed for your transmitters. Most wireless mic systems have built in noise reduction circuitry based on compression/expansion or "companding". Using another brand may give strange dynamic results.
Good luck!
 
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