The following webinar is now available for On-Demand Viewing:

 

antennamatt , an electrical engineer and the Business Development Manager for Molex, recently joined us here on the element14 community to give members an overview of the RF design process, including key considerations and constraints to consider before selecting an antenna for an application. During his presentation he went over some common IoT frequencies and protocols; let us know when, where, and why to use internal vs external antennas; and also went over different antenna types and why you would each one. He also covered high level actions and practices that developers should pursue to optimize RF performance with off the shelf antennas, as well as, gave us an overview of custom antennas and when they make sense. During this webinar attendees who had good questions for antennamatt were rewarded with a free antenna sample kits that included Bluetooth / Wi-Fi Antennas; GNSS Antennas; Near Field Communication (NFC) Antennas; Cellular Antennas; Ultra Wide Band (UWB) Antennas, Industrial, Scientific and Medical (ISM) Antennas, and Combo Antennas (Wi-Fi, GPS, ISM, Cellular).

 

This webinar should be of particular interest to our members as there have been several exciting projects as well as product reviews involving Molex Antennas!

 

You can also download Antenna Datasheets,  Quick Reference Guides, and a PDF version of this presentation by clicking on the attachments below!

 

Here are some honest & unbiased RoadTests & Reviews from our community members:

 

 

Here are some projects using Molex antennas from our community members:

 

 

Here's a Tech Connection on antennas and Optimal RF performance that was sponsored by Molex:

 

 

 

Q&A Session

 

What is RF engineering really about?

 

RF engineering is the practice of designing electronic features and components into an electronic system to enable it to have good - or to improve the RF (Radio Frequency) - also known as wireless, performance

 

What makes antennas special?

 

Many things can make an antenna good or better, but the answer is not always as simple as one antenna always being better than another because a big part of how good an antenna performs, depends on how well it is engineered into a system. There are many rules and best practices that if followed, will improve how an antenna functions. Much of this presentation covers this. But in its most simple level, an antenna with a higher efficiency rating than another antenna - is the better antenna (but of course it still needs to be optimally engineered into the system)

Does RF antennas really need a lot of engineering?

 

Often, yes - but general, antennas that are soldered onto a PCB need more engineering.

 

Can a single RF antenna run every band and frequency?

 

It is theoretically possible, but the overall performance will not be good. The more an antenna is designed for specific frequencies, usually the better it will perform.

 

How is the manufacturing of RF antennas done?

 

Many ways. It always involves a metal pattern or form - that is bent, stamped, plated, or printed - often on a non-conducting material like plastic, ceramic, or a printed circuit board.

 

What's the difference between cellular network, WiFi, and NFC antennas?

 

Each of those items, are wireless protocols - similar to programs on a computer. Each of those protocols are assigned a range of frequencies (and rules  - such as how much power they are allowed to transmit at), by organizations like the FCC.

 

How is the manufacturing of RF antennas done?

 

ow speed (lower frequencies) have a larger bandwidth and generally this means that a larger antenna. At ultra high (usually > 10 GHz) frequencies, antenna performance becomes increasingly dependent on precision as the antennas typically get smaller and smaller.

 

Why is LTE very difficult for small devices?

 

Carriers (Verizon, AT&T, etc.) often require at least one lower band (e.g., band 12 ~ 600-700 MHz) frequency. Lower frquency=higher wavelength, which likes to see a larger antenna size - and a larger ground plane ( relates directly to size of the PCB if this is an SMT antenna).  Small devices often are small to the extent it is difficult to get 'good' LTE performance  because either a large (external / cabled) antenna or an SMT antenna with large enough ground plane to get good performance.

 

What is an antenna array?

 

An antenna array is more than one antennas that are connected to the transmitting/receiving RF electronics, designed to perform better than a single antenna. There are many array configurations, sizes that can happen and many different ways electronically how to utilize arrays of antennas.

 

Can we transfer large data using the antenna arrays of 5G for short distances?

 

If there is a 5G high-speed site available, it is feasible to transmit large amounts of data over short distances,  though it does consume network resources and is probably not the most efficient or lowest cost way to transmit lots of data. There may be some provisions in 5G to allow for high speed transfer over short distances that bypass expensive network resources, but this is not well known or popularlized t this time.

 

How are the bands of RF antennas decided?

 

National organizations like the FCC assign frequencies to owners (literally are sold), including 'unlicensed' bands that allow private use. Protocols like WiFi, Bluetooth, LoRa, etc. - are also regulated by the FCC (and similar groups) in terms of what frequencies a protocol can use, how much power they can transmit at, etc.

 

What price difference can be expected between custom vs. Off the shelf. You indicated a lot. What is a lot in terms of percentage? 10% more, 20% more >50%

 

Off the shelf do not typically require custom development (which can be from 10s of thousands's of dollars and up, and take 3+ months on up to provide just the antenna). Off the shelf are available right now, do not require up-front investment just to acquire the antenna. Custom antennas can make sense as the volume gets high (usually over 100K units a year) - as the volume increases, a custom antenna can be the same or cheaper than off-the-shelf, but there still is that up-front- investment.  Off-the-shelf antennas can require time and money to engineer into a device however, and that can range from zero to hundred's of hours and potentially some expert help - if necessary to test and measure and optimize results

 

I am onto designing a custom antenna for one of my project so I want to use a single antenna and special hardware which will switch between bands depending upon the usage? Is something like that possible?

It is possible to design a single antenna for mutliple frequencies - but it may not be favorable / as feasible depending on the ranges of frequencies, the performance expectations for each frequenc range, and the size available for the antenna and groundplane. In reality, if you want to switch between frequencies, it is typically the RF electronics that are feeding / driving the antenna - which is where the switching is taking place.  Do you have an RF electronic chipset/ supplier in mind? or are you also designing this yourself?

 

Does molex offer antenna design consultation services to a purchaser?

 

Yes this is offered.  Simple questions and review are easy to respond to - work through your Molex contact such as Avnet/Element 14, etc. - and if more detailed testing and antenna optimization services are needed, these are typically at a fee. Depending on the complexity of your need, typically the amount of RF consulting that may be needed can range from a few hours, to a day or two of time from a Molex RF expert. This may also involve testing and documenting RF performance on your part in a Molex antenna test chamber.

 

 

Is the ground plane affects with a PCB antenna better or worse than a ceramic antenna?

This really depends on the merits of the design between a PCB (you mean a PCB trace, right?) .vs. a ceramic (SMT) antenna. Almost always,  a ceramic PCB antenna will be more efficient and may have smaller ground plane requirements than a PCB trace antenna. But you would need to compare specifications or better yet, test the performance.

 

Can a metal housing itself used as an low frequency antennas?

 

Metal housings are to be avoided with any internal antenna - but sometimes that is not possible.  To peform better, the housing has gaps or 'RF windows' proxy to the antenna.  Or better, use an external antenna. To your question of low frequency, there may be some advantages of lower frequency being able to find and radiate through RF

 

Using a Raspberry Pi as an example, they went from a PCB antenna to a ceramic antenna. would this be better or worse using  a metal case?

 

Various Raspberry Pi versions - for instance Zero has a U.FL connector for a cabled  antenanns. Pi 3 has an on-board ceramic antenna. I am not familiar with all the variants of 3, but it looks like at least some people have hacked it (if not there must be alternate versions of 3) that place a U.FL connector. Better RF performance may quite likely be acheived with some high efficient cabled antennas (such as Molex 146153) - than with the on-board chip antenna.  But realize that is just the board itself. If you place it in a metal case, then the onboard chip antenna will be challenged to radiate / receive through the metal case well, if at all. Bringing the antenna away (external) from the housing will give you much better antenna performance.

What are the spiky looking things in RF Test Chamber?

 

RF absorbing foam.  It enables us to obtain much more acurate results in sensitive testing so that we are able to measure how efficient the antenna radiates and in what directions.

 

Can wireless charging and data transfer take place together?

 

Yes this is done all the time. For instance, when a mobile phone is being wirelessly charged, it can make / receive calls, work the internet and probably get a good GPS signal as well.

 

 

What's your antenna recommendation for UWB localization applications?

 

Not sure what you mean by localization - but a good UWB antenna is Molex antenna series: 146184

 

Can you share with us underwater use cases?

Underwater is very challenging as most common IoT frequencies do not penetrate deep into water. Molex does have experience working with a manufacuturer of RF enabled swimming goggles, but they are not designed to operate while deep under the water.

 

Have the Molex antennas been used as components of more complex antennas such as phased arrays or as dish antenna feeds ?

 

Molex is suppplying antennas that are used as arrays in cell towers. Molex has an RF group as a sister organziation to the Antenna group that services carrier and high frequency transmission that does get into antenna elements, wheras this group typically focusses more on IoT frequencies - though now into mm wave for 5G.

 

I am trying to build an IOT sensor that will transmit from inside a pool. submerged.

 

You probably need to bring the signal from the sensor as close to the surface as possible - most IoT protocols (above 433 MHz) do not penetrate deep into water. Getting the antenna above the water should be your goal; partial / temporary submersion may be ok for transmit / receive enough data for the application.

I work with ant molex 146200

 

146200 is an excellent LTE SMT antenna and available in left and right side feed.

 

Have you investigated the 3D printing of antennas (if yes, how do they perform) as it seems to be an ideal technology for making antennas?

 

Do you mean printing the antenna traces onto a PCB or Flex membrane? If so, yes that is done and can produce fairly good results. If you mean printing antennas on 3D printed surfaces, that can work but there is risk involved with this due to the fact that 3D printed objects have a rough surface, that does not produce very consistent and precise base for antenna traces. This becomes more extreme - the impact on RF performance with higher (>2GHz) frequencies makes dependable repeateable perormance less and less likely as the frequencies are higher.

 

 

Which is the optimal distance between components which radiates RF interference and how to shield these components in order to minimize the impact of cross interference?

Items that radiate RF interference, ideally are shielded with a metallic shield onto the PCB (according to best practices, beyond the scope of this RF seminar/workshop).  There should also be seperation from the antenna and this sheild -How much, it depends - best to read the detailed antenna specification that  should provide such guidelines. In general, here are some good alternate guidelines: If SMT, a good minimum distance recommendation is 5 mm, more is better - like to see > 20 mm from an adjacent ground plane.

 

In a dynamic environment like an automotive or industrial application is using a higher gain antenna more useful?

 

That is difficult to say. High gain meaning that the antenna pattern is biased in one or more directions .vs. low gain which is more omnidirectional. You need to think through the needs of the application, how the devices need to communicate - their orientation(s) and this should provide you with useful clarity on that.

 

What are SigFox? Can you give an example?

Sigfox is a wireless protocol (that you can find RF chipsets which support it), transmitting in the 928 MHz (in N America - and 868MHz in Asia / Europe). It is good for lower bandwidth applications, has good penetration, and if properly implemented, tends to be very low power - enabling a battery powering the device to last for many years.

 

How are the bands of RF antennas decided?

 

This is done when the antenna is designed