A few weeks ago I emailed RF Venue begging to demo their Spotlight Nearfield antenna pad. They had just showcased it at Infocomm 2017. There they showed how it was able to really reject the massive amount of background RF that was all over the expo floor.
And after a little bit of exchanging emails I was able to score a demo unit to test for an upcoming live webcast. And at first you may say why the Spotlight, why not a more traditional antenna system like a sharkfin antenna?
Well because of what the Spotlight can do! It really only “sees” RF sources within a 100ft of itself. Here is the promo video explaining this concept.
And now that you’ve seen how they are suppose to work check out the room plans for how this convention floor was suppose to be laid out.
Each Orange-X is 2 Shure SLX4 wireless handheld 30mw kits. Each Red-X is a giant LED Video Wall that we know, from RF Venues Blog post, create all sorts of RF problems within 40ft of them… or in my case.. there isn’t much on the big stage that isn’t within 40ft of either video wall. Now frequency coordinating 8-9 wireless kits in a Shure freq band normally wouldn’t be an issue, but the SLX4 systems max out at running 12 safely in optimum conditions… and I needed to run 9 in less then ideal conditions. I should also note that the ceiling in this convention center is metal and metal I-Bean raffers. We could barely get phone signal. The venue has all the makings for a RF echo chamber. This is why I felt the RF Venue Spotlight would be perfect to test under the circumstances.
The Spotlight is made up of a very strong rubber. It’s about as thick as my hand and pretty flexible. They also claim the BBC cable coming from it has a 50lb tensile strength… is that good? Well maybe, it depends. Some BNC cable makers claim a tensile strength of 170lbs… but those cables haven’t been soldered and mounted permanently to an antenna. So it’s hard to say if 50lbs is good but I can say it’s been placed on every piece of marketing material that RF Venue puts out about the Spotlight Nearfield antenna; so it’s safe to say they are super proud of it.
So how did the RF Venue Spotlight antenna do? Famiously! I tested it by setting a transmitter at the small southern stage to the same frequency as my reciever on the main stage. The RF Spotlight was connected to a 100ft coax run and plugged into a Shure SLX4 reciever. Between the unique pickup pattern of the Spotlight and the 9dB loss from the BNC run I could not pickup a signal from the TX that was 300ft away. Could not ask for more!
Now you might say that a lot of that has to do with the 9dB loss from the BNC run and the fact that 30mw just isn’t alot of power. If you read the article about range testing the G3 mod you will see that 30mw can go the distance and defiantly go far enough to cause static and interfere with someone else’s reciever. But it’s more then just the 9db loss from the cabling.
The unique pickup pattern of the Spotlight is kinda like a figure-8 microphone pattern except it’s pointed up… and down! You can think of it as like pointing a cardiod microphone straight up. It will get all the audio above it but as the audio moves away horizontially out of the focus it will roll off in amplitude faster then if it was to move away from just an omni microphone. A Stock Whip is like an Omni and the Nearfield Antenna is like a cardiod. The inverse square law is in play as to what RF the reciever sees but the Spotlight also is using its horizontal rejection to decrease what it sees. And on a side note, it also sees all RF below it too in a cardiod pickup… so if a TX in buried underground… you’ll see it!
So lets look at the charts RF Venue published from InfoComm again since we now know what we are looking for with this antenna. The areas in blue is the RF noise floor. At InfoComm they were using probably less then 10ft of BNC so all the crushing of the noise floor was purely from the pickup pattern of the Spotlight, though a basic inline -dB pad would also do something simular. Now for what makes this antenna really cool; The areas circled in red are RF signals from devices in the room that are far off on the expo floor. As you can see all of their peaks are either crush or significantly rolled off based on their distance to the RF Venue booth. The fact that they all decreased at different rates is evident of pickup pattern. You wouldn’t see different rates of decrease from a basic pad.
So should you buy one? In the immortal words of Senator… It depends? The RF Spotlight is the future of what film sets need to start embracing. The idea of remoting your antennas closer and closer for solving RF issues is a very NYC Broadway concept, where transmitters are always set under 30mw and they have to work with neighboring playhouses to keep from stepping on eachother.
So who should be buying these? Stagestages and rental houses! These should be mounted in the ceilings of every sound stage and have an output port against a wall that a sound mixer should just have to take a tap from. Instead of setting up Sharkfins and also picking up the soap operas signals coming from the stage next door, imagine having one of these hoovering over your sitcom. Imagine running all your Lectrosonics at 10 or 25mw and not having to change batteries all day. With a ever shrinking RF spectrum for us to work in AND share with TV stations, the RF Venue Spotlight is pioneer blazing a trail towards a new RF frontier.
Andrew Jones is a location sound mixer based in Los Angeles. He started in the TV and Film industry in 2004. You can email him at Andrew@HoldForSound.com