hi I'm Stuart and welcome back to Shaw's whiteboard sessions today we're going to be looking at antenna selection and placement like microphones antennas are transducers converting energy from one form to another so in the case of transmitting antennas for any monitoring systems were converting current into electromagnetic waves and for your wireless microphone systems we're doing the reverse we're taking those electromagnetic waves and converting them into current the size of an antenna is related to its wavelength so for VHF systems from say 172 to 16 megahertz you're looking at a wavelength of approximately 1.5 meters but in the UHF range from 470 to 790 megahertz say the wavelength shrinks right down to maybe about half a meter design of antennas also determines the performance so depending on the actual design you can add features like directionality increased forward gain and limit the bandwidth of those antennas so the two types of antennas we generally use with our wireless microphone systems and in-ear monitoring systems are either omnidirectional or directional so omnidirectional antennas are typically either quarter or half wave so what we mean by that is if the wavelength of UHF is half a meter then a half wave antenna would be twenty five to thirty centimeters long take for example this half wave antenna another characteristic of omnidirectional is that they are vertically polarized so that means they receive in this orientation so if you were to point these directly at your transmitters you would well you would lose performance in the system because you're aiming a null point at your transmitters and lastly they have uniform sensitivity so it doesn't matter whether your transmitters are being received from this orientation or either side or the rear they will pick up the same amount with an omnidirectional antenna some characteristics of directional antennas are you have increased on axis sensitivity so if this is our take UA h74 paddle antenna you will get increased forward gain in this orientation so this is useful in either harsh RF environments where the noise floor isn't ideal and you just need to kind of block out some of that noise and get the directionality you need towards your transmitters or it's also beneficial if you need some additional range from your system because again you can cut out that noise and just focus on the transmission that you need to receive another common question that we receive particularly with these paddle antennas is active versus passive we always feel and hear that active antennas are better you get more RF received at your receivers now it really all depends on the application because with active antennas you're boosting the amount of signal that is received at your receivers but you're also bringing in a bit extra noise into the system as well and generally the amplifiers on the antennas are really only there to compensate for losses within the cable rather than increasing the forward gain of the system so the benefits you're getting from those is you're compensating for those cable losses so when it comes to placing your antennas there's a few things that you need to keep in mind one of those things is separation between your receiving antennas in order to maintain diversity performance you want to keep a minimum of about a quarter wavelength spacing between those but ideally if you can get them about a wavelength apart then you will have strong performance from your system if you get those antennas too close then you run the risk of things like multipath interference causing dropouts and if you separate them too far then the system essentially views them as two separate antennas so you lose the benefit of diversity another thing to consider is your transmission to receiving antenna distance you want to keep about three meters as a minimum from your transmitter two receivers just so that you don't forget things like RF overload and overload your receivers two things antennas and RF really dislike our metal so things like metal mesh fences or cages that essentially just blocks the RF from coming straight through to your receiving antennas and water and as people we are largely made up of water so when you run your event you want to try and get your antennas up nice and high clear the heads of their people that are attending and stop them from as absorbing all that RF from reaching your antennas you also want to avoid sources of interference so one thing we kind of advise against is mixing both wireless transmitters and receiving antennas in the same racks because if you have an in-ear monitoring system and a wireless mic system in the same rack the transmitting antenna for your any monitors is going to be outputting a lot more power and will desensitize the receiving antennas of your wireless racks another thing is if you're using multiple receivers in a given rack then it's always a good idea to remote those antennas so that you can get them up nice and high and get some good line-of-sight to your transmitters thank you for joining us for another episode of the show whiteboard sessions if you'd like to know more by wireless microphones or in-ear monitoring systems then we do host our wireless mastered seminars here at Shaw UK and to make sure you don't miss any more episodes in the series then please subscribe at losing your voice stalker UK so when it come in when it come when it come in abbadabba true so with an omni antenna

hi my name is Danny 140 I'm an application engineer with regal technologies and today I'll be demonstrating a few simple tests you can perform on antennas to help you choose the best antenna for your Internet of Things application since I'll be using Bluetooth later on the send information I want to double check that our antennas are rated for the 2.4 gigahertz bandwidth so to start off with I have two antennas I have antenna a and antenna B and I'm going to start off with performing to see if they're rated for the two point figure her bandwidth by attaching antenna a to the transmitter our spectrum analyzer and then going and hitting TG and then turning it on at this point it's doing a full sweep of the entire spectrum and just getting the power of being transmitted and capturing it on the secondary antenna I'm gonna go over to the peak section and see if this is rated to for the 2.4 gigahertz bandwidth so I'm gonna actually bring it over there so we're right around there so as you can see this antenna is rated for the bandwidth will be using now to do antenna being the same test and let's bring this and as you can see as well this town antenna has also rated for the 2.4 gigahertz bandwidth so both are able to function in the Bluetooth Wi-Fi or ZigBee realm for our antenna performance test I use our DSA 875 TG spectrum analyzer but if you are testing in the 2.4 gigahertz bandwidth for either Bluetooth ZigBee or Wi-Fi technology you can certainly use our DSA 832 etg spectrum analyzer which has a range of 9 kilohertz to 3.2 gigahertz in order to get a sense of how these antennas will do at the 2.4 gigahertz range I'm going to perform a vis wear test just to see the reflection coefficient and how well they're performing and how efficient they are to do this I'm going to hit measure actually first I'm going to hit frequency and change this to 2.4 gigahertz then I'll hit measure and turn on visitor and then I going to measure set up and hit Cal open and then I'm going to attach our antenna of a to the VIS wear bridge and I'm gonna go ahead and hit this work so right now it's performing right around 10:00 or so for viz we're ideally we should be looking at around 1:00 so this is reflecting quite a bit of the signal that's being pushed into it now we'll compare this with intent our antenna B which this actually has a visitor of right low right around 1:00 or so so this is actually a lot more efficient than our antenna a so I would assume that this would actually give us further distance and would use less power for this wear test I used our VB 1032 vis where bridge which has a range of one megahertz to 3.2 gigahertz along with our spectrum analyzer in order to show how the reflection coefficient will have an effect on our two antennas I've connected antenna a to our Nordic and our F 52 board and I'm now going to connect it to my iPhone and then I'm actually going to show how the distance is affected between the two tenna a dropped right here so now I'm gonna go see how much far their antenna B will get us now that perform the same test but now with antenna B I'm going to connect my iphone to the Nordic NRF board and now we're going to go outside I'm now using antenna B and I still have connection where antenna a dropped and I'm gonna go a little bit further and this is where antenna B drops so we got about eight to ten feet more of distance but if you don't need the distance you can always go ahead and save power the total cost to perform all the tests shown in this video at the 2.4 gigahertz range is a little under $4,500 if you have any questions regarding the products seen in this video or any of our products please contact us at Regal or visit regal na komm for more information