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First things first: Don't leave placement of the antenna until the last moment

Demand for machine to machine communications – M2M – is growing rapidly and that is pushing more companies to include wireless functionality in their products. Colin Newman, sales and marketing director for antenna specialist Antenova, said: "Eighteen months ago, many products weren't wireless enabled. Today, companies are looking to include it. While some have technical knowledge, many of the companies we typically deal with have little rf expertise."

And getting hold of good quality rf engineers, Newman pointed out, is difficult. "Companies are looking for outside support and that's something we can provide."

Antenova was launched in the early 2000s to commercialise antenna research conducted in Sheffield and Brisbane. As the company grew, two types of customer emerged. "We have always served customers in the M2M market," Newman observed. "These were typically tier 2/3 developers buying standard products and rf modules."

The other group of customers was quite different. "We also developed IP for custom antennas for tier 1 companies," Newman continued. "These devices were used in mobile phones and are now implemented in smartphones and tablets." This market has become very competitive over the years, he continued, noting that demands are high. "It required a lot of resources and a lot of investment. Developing a project can take up to two years and you often win only a few of the bids."

Servicing the tier 1 sector wasn't bringing the expected results and Antenova recently decided to focus entirely on the M2M sector, rebranding itself as Antenova M2M. "We're developing standard products," Newman explained, "with off the shelf solutions helping companies get products to market quickly."

Antenova offers a range of antennas, aimed primarily at use in hand held and portable devices. "They cover most wireless frequencies," Newman said, "ranging from 868/918MHz to 2.4GHz, as well as GSM, LTE and GPS devices."

Most of the company's business comes from antennas developed for 2.4GHz and mobile applications. "We haven't been offering products for the lower end of the spectrum for too long, but we're already seeing growing demand for these in such applications as security and smoke detectors. Here, installers don't want to run cables, so have gone wireless, but because the signals have to go through walls and so on, they are favouring lower frequencies, such as 868/918MHz."

Antenova is also developing radio modules. "There are two advantages," Newman claimed "If customers buy a complete radio with antenna, they don't have to worry so much about laying out the board, matching and so on – all of this has been taken care of and the module can be treated like a digital component, although care still needs to be taken about antenna placement. The other is time to market, which is quicker with off the shelf modules."

Asked what's driving the development of Antenova's products, Newman said: "It's the need for the antenna to be as small as possible and to be low cost. But it also needs to offer as good a performance as possible, particularly if the customer has quality of service concerns."

Battery operated products require an antenna which has a high operating efficiency, which helps with extending the operating time between charges. "That's particularly important with GSM applications," Newman pointed out, "where the antenna can 'bump' the PA and drain the battery more quickly."

Dr Devis Iellici, is Antenova's director of research and development. "When you think about an antenna, you initially think about large external devices. Many engineers don't realise it's possible to make one much smaller."

He said the trick is to use the device itself as part of the antenna. "However, that makes integration important. While the device behaves like an antenna, it's a challenge to achieve good performance in many designs." But making the device part of the antenna doesn't work in all applications, Dr Iellici added.

Standard antennas are also easier to tune and match. "There needs to be a matching circuit between the radio and the antenna," Dr Iellici continued. "It comprises some inductors and capacitors which match the impedance of the two elements – typically, this is 50?. With Antenova antennas, some components can be used to adjust the resonant frequency, allowing the device to work with different devices and to offer good performance.

"If the customer has some experience, they can do this themselves. If not, Antenova can offer full support in designing matching circuits."

Newman claimed that, because many companies don't have engineers with rf experience, integrating communications into a product is often left to a digital engineer. "And they can often leave this element until the last moment. They'll choose an antenna and find somewhere on the board to put it. Nine times out of 10, they come to us with a design – sometimes even the plastic enclosure already designed and manufactured – and say 'I need a 2.4GHz antenna to go here'.

"This isn't the way to do it. You have to think about the antenna's position first; another part can be moved around the board, but the antenna can only go in certain positions. And, because it's a standard antenna, there will be other interactions, so engineers should position the antenna first, then design the rest of the product."

Dr Iellici pointed out that if the design only uses a single high frequency radio, then the result 'may not be too bad'. "But for those applications which will use the cellular radio system, where a wide range of frequencies are being shared, it can be a disaster – there would need to be a redesign, and that's a waste of time and money."

Newman said Antenova is also partnering with module and chip manufacturers to develop application notes and reference designs, looking to make it easier for customers to 'drop in' a solution.

Another reason for getting the design right is if the device is to be sold globally, particularly in the US. "Devices which are marketed in the US need to have a minimum over the air performance," said Dr Iellici. "If the antenna has been designed in badly, the performance won't be what you expected and you will be unable to put it on the US market. While things are a little more relaxed in Europe, it's still important."

Power output is not critical for the antenna – they are usually capable of generating more power without linearity problems – but the designer will need to fulfil minimum and maximum gain requirements for the antenna. Other specifications which need to be considered are total radiated power and the isotropic sensitivity.

"Poor sensitivity could indicate an antenna problem, but it could also be a radio problem," Dr Iellici noted. "And, in some cases, it could be due to noise generated by the design itself. Customers will usually blame the antenna, but it's often the design which is noisy. An example is when the device uses a GPS, which works at a lower signal level. Unless the board is quiet at the GPS frequency, performance will be degraded."

Asked for his recommendations to designers, Newman concluded: "Think about where the antenna should go, then put the radio alongside. Ask if you're not sure."

Author
Graham Pitcher

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