Antenna coverage for big area

[viktor92]

Dear all,

 

I am looking for antennas which can cover range of outdoor area with size of 75 x 35 meters.

 

Kindly note I use:

- Sennheiser ew100 G3 (626 - 668 MHz), 2 pieces.

- Sennheiser XSW2-ME3 (614 - 638 MHz), 2 pieces.

- Sennheiser ASA 1 - Antenna distribution system.

 

May you please advise:

- Which antennas to use?

- Are boosters required?

- RF cables with minimal loss of signal? If I extend cables should I use boosters?

- Location and position of antennas (height)?

I will be very thankful if you can advise the brand and specific model of the products?

 

Many thanks in advance.

Viktor.

[Stuart91]

I'll start with one quick tip - get the antennas reasonably high, at least over head height. Human bodies are great at blocking RF signals, especially if the area is crowded.

 

You will lose less RF strength in a cable than through the air, so if you know where the mic users will be spending most of their time, concentrate the antenna coverage there and run cables back to the receivers if you have to.

[timmeh2]

Hi

 

I believe this is the 2nd time you've asked this question.

 

The area you are trying to cover is 2625m2, however in radio world you need to think in 3 dimensions. If your aerials are 5m up in the air, then the space you are considering is 75x35x5 which is some 13,125m3.

 

A bit of CAD and experimentation will help you here, find out how far you can get a mic from one of your recievers, then use the 2/3rds rule and space your aerials accordingly.

 

As stuart says, you get far less loss through cables than in the air so be prepared to run lots of BNC and XLR.

 

All the best

Timmeh

[sunray]

There's lots to consider.

I assume this is an arena for a public display of some sort. In that situation I will often mount a receiver on top of a 3m LS pole and run a 2pair (audio and 12V) cable back to the mixer and generally that will suffice.

 

However if there is likely to be lots of large bits of metal involved (think emergency services demonstration with fire, ambulance, tow truck etc.) then serious effort needs to be put in.

 

I'll always prefer to run audio cable rather than RF if appropriate due to the dramatic difference in losses involved.

[david.elsbury]

I presume it’s in his water park. Look at the location of the transmitters and put antennas within close proximity and run good thick coax to the receivers. Don’t put the receivers outside!!! Not for a permanent install...

 

How far will the receivers be from the performance area?

[paulears]

600MHz is not ideal to use coax, and it's just impractical to contemplate long runs. Assuming a method to keep the receivers dry, I too would prefer to run audio rather than RF. I suspect that here with just a few channels and limited kit, the clever options are not possible. If you do happen to have some long lengths of very low loss feeder there is one thing you could try. It's rarely done nowadays but you can feed one receiver with a passive combiner, and space out antennas then combine them so that wherever the transmitters are, one receiver is within range. Of course the long cables cut down the levels but signal strength is rarely a real issue with radio systems, it's the sudden nulls where there is no signal at all. Years ago we did this trick on long thin outside broadcasts where presenters needed to walk down a grass path in the country towards the camera. Songs of Praise was the one I remember where we were a a stately home and Harry Secombe was presenting walking towards the house from the ornamental statue at the limit of the zoom. We hid the aerials in the bushes, with the receiver about half way down. So as he walked end to end as he came up on one antenna he dropped down on another. I think we had three aerials on each of the antenna inputs of the VHF diversity receiver. Worked pretty well. Ironically they didn't like the time it took to set it up!

[TonyMitchell]

You'll fully cover a single area 75m x 35m with a pair of Sennheiser A2003 UHF antennae so long as you separate them, get them up high and experiment with optimum position. We do this week in, week out using G3-300 kit, in different locations, often achieving good TX distances well over 100m from the antennae. We keep the coax cables under 5m and don't use boosters.

[sandall]

Songs of Praise was the one I remember where we were a a stately home and Harry Secombe was presenting walking towards the house from the ornamental statue at the limit of the zoom

IIRC Mr Secombe presented the long vanished ITV "oppositionn show" that used tracks rather than congregations - I don't think he ever appeared on SoP

[MarkPAman]

If one can trust Wikipedia, he did.

[paulears]

He most certainly did - I never did any of ITVs Ons - was always funny when the power supply in a church was considered insufficient. LDK Philips cameras on the scanner were rather nice OB cameras, but needed a fair chunk of light. a cut down 6" nail was always a good way to get a few extra KW. BBC did 'as live' church stuff back then. I don't think anyone mimed. Harry Secombe and another well known singer of the day - can't remember his name. We also did a few seaside specials with the same crews, but they were heavily edited as they stuck Gerry Cottle's tent up at a seaside resort, then got the people from the local summer shows to come and do their acts - but then they mixed it up, so they'd say "Give a big Torquay Welcome to Peters and Lee ................ but they're not here" - then they'd record Peters and Lee at Blackpool a week later. I was a sound assistant for a short while followed by a bit of cameras assistant - a summer job really. Radio mics were rather odd, but surprisingly good quality. The OB van had them in a rack, lots of small modules - but we used the battery receivers more often.

 

Big Clive would perhaps be a good person to ask about the Edinburgh Castle event - that's a pretty large area and they have people doing stuff all over it with radio mics?

[sunray]

600MHz is not ideal to use coax and it's just impractical to contemplate long runs.

On a fixed site (night club) some mic's didn't have much range. The installers had been in several times and declared a clean bill of health but I was asked to have a look at the RX's on the day after the 1year warranty expired. I found the aerial was a short length of braid stripped from the end of the TV coax feeder then over 100m of it meandering around the tortuous route from the 2nd floor main dance area to the basement amp room adjacent to the chilled beer cellar, there were several chocbloc joins and the split to 4 RX's was simply a chocbloc with 4 coax's to the EDC VHF RX's. Just unplugging 3 of them saw a significant increase of signal strength. Now the irony is the audio from the RX's was standard mic cable running back up to the mixer just a few metres from the aerial. My solution of simply moving the RX's to the void under the mixer position gave full strength signals right across the stage and dance floor area.

Assuming a method to keep the receivers dry, I too would prefer to run audio rather than RF.

I automatically look for this option, I've made up a number of 2 pair cables of up to 100m on drums with XLR and DC power connectors and find it much easier than stubborn heavy coax, and of course there is virtually no loss involved. I've used a variety of methods to weatherproof RX's, (especially washing up bowls)but there is one site where I mounted an ABS adaptable box 30ft up on a corrugated steel building, containing 2 Audio Technica VHF RX's in 1996 and added 2 Trantec S4000's around 2005, these are used on a daily basis teaching Horse riding

I suspect that here with just a few channels and limited kit, the clever options are not possible. If you do happen to have some long lengths of very low loss feeder there is one thing you could try. It's rarely done nowadays but you can feed one receiver with a passive combiner, and space out antennas then combine them so that wherever the transmitters are, one receiver is within range. Of course the long cables cut down the levels but signal strength is rarely a real issue with radio systems, it's the sudden nulls where there is no signal at all. Years ago we did this trick on long thin outside broadcasts where presenters needed to walk down a grass path in the country towards the camera. Songs of Praise was the one I remember where we were a a stately home and Harry Secombe was presenting walking towards the house from the ornamental statue at the limit of the zoom. We hid the aerials in the bushes, with the receiver about half way down. So as he walked end to end as he came up on one antenna he dropped down on another. I think we had three aerials on each of the antenna inputs of the VHF diversity receiver. Worked pretty well. Ironically they didn't like the time it took to set it up!

We had an event where we wanted to use radiomics over a 3/4 mile track for cars, bikes and horses. I suggested this approach and was laughed out of the park, however no one came up with a better idea so I experimented and found it worked, but over 200m of feeder the loss was untenable, We installed 3 racks containing 4 RX's, a home made aerial combiner/amplifier/splitter and a car battery and loads of aerials on the 10ft LS poles with silly amounts of coax. It took a lot of careful mixing to tame the thing but we got there... Just!

[Jon Wiles]

wow, there's a name I've not heard in years............EDC,.......Dorset's finest!

Remember going there to collect some mics for our school production in Bournemouth back in '85/'86

[sunray]

wow, there's a name I've not heard in years............EDC,.......Dorset's finest!Remember going there to collect some mics for our school production in Bournemouth back in '85/'86

 

And to think they used to be one of the most highly regarded radio mic manufacturers.

[empyfree]

Don’t know if you spotted the “anti drone tech” on the news a few weeks ago... they had a lovely custom enclosure high up on a mast to keep some electronics dry.

 

Actually, on closer inspection it was a plastic car roof box!

[sandall]

He most certainly did - I never did any of ITVs Ons ............ BBC did 'as live' church stuff back then. I don't think anyone mimed. Harry Secombe and another well known singer of the day - can't remember his name.

This must have been after my time. I edited SoP & various offshoots regularly throughout the 1980s & early 1990s, when, apart from the odd extravaganzas, usually by the same couple of producers, it was largely church-based, with 2-3 day OBs & "serious" contributors & presenters, not "celebs". During that period Mr Secombe was fronting ITV's Highway, which was a very different show, with singers in unlikely places miming to playback.