Antenna Technology Quiz

I have a few concerns with the quiz. There is a lot of information that is questionable and blanket statements that are incorrect. It is also of note that antennas do not support protocols but instead support bands of operation where those protocols are commonly used. Protocols are also not inherently frequency locked.

Alex,

Thanks for your feedback. Could you name a question that you disagreed with?

Randall Scasny

-element14 team

Alex,

Thanks for your feedback. Could you name a question that you disagreed with?

Randall Scasny

-element14 team

My primary concern is the statements of antennas supporting specific protocols. Antennas are agnostic of protocol. Protocols are agnostic of frequency. That being said, standards will have operating frequencies specified like LTE with its various bands. (Questions 9, 20, 25)

Question 11 concerns me for the already stated reason of antennas not supporting protocol but also for reasons relating to 5G. The question assumes that 5G only exists in the context of massive MIMO mm-wave. The objective of 5G is not just packing more antennas at a higher frequency into a single unit. It should also be noted that antenna design and placement is also agnostic of protocol.

Question 13 does not include units on directivity. This makes the question ambiguous. Is it 1.5 dB or 1.5? Indication of no units should be included for clarity if that is the case. Question 14 should also include units to remove ambiguity.

Question 21 assumes that the dipole length is fixed, Once the dipole length starts to increase it will no longer look like a donut.

From the phrasing of question 23 it leads me to believe that the beamwidth of an antenna is symmetric. The antenna beamwidth is commonly defined in terms of 3dB, 10 dB, and first null beamwidth. The first null beamwidth is no longer on the main lobe. It would better to phrase the question in terms of amplitude since 'identical points' implies some level of symmetry.

I also have issues with the typos since technically question 4 has two correct answers.

Alex,

Thank you for the detailed comments. I have the day off today, so it will take me until Monday to respond to all of your concerns.

But let me respond to question 20.

    4G

    GPS

    Wi-Fi

    Thread

    All of the above

This question came out of the datasheet: https://www.molex.com/webdocs/datasheets/pdf/en-us/2068663000_ANTENNAS.pdf

From the datasheet:

Protocol: BT, Cellular, GPS, Wi-Fi

When I get back on Monday, I'll contact the manufacturer (Molex) with your comments.

Have a good weekend.

Randall Scasny

-element14

rscasny alex alex.colpitts is quite right Antennas are AGNOSTIC they are kind of "stupid" if the frequency is right, and you put a signal in (any type)  it comes out the other side.

the best analogy and it bad it behaves sort of like a transformer where W_p ~= W_s!  NOW saying that with antennas this is not true as you have all sorts of losses: Cable, VSWR, Antenna Design etc. Some multi-element designs in which one or more radiators are driven. This type of antenna has a GAIN factor. Also Parabolic Antennas or the common name would be a DISH has a GAIN factor around a center frequency and as you go off-center it less efficient or sort of like a bell curve. As a side note manufacturers will tell you only what you want to hear and they fib! So where they say this antenna is good for Wifi you should know the frequency and radiation pattern of the thing: Don't use RJ-59 75ohm coax stuff they use on your TV when it calls for RJ-58ohm!! 

If  you are ever in doubt here are two sources that are bibles:

handbook

antenna

Hi Alex.

I'm starting to go through the comments you had about specific questions. I'll try to address the questions that I can. For the remainder of the questions, I'll be talking to my contact at Molex.

Question 11:

True or False: Designers of 5G wireless technology products will need to not only incorporate an array of high-frequency antennas into their products, but also determine antenna placement best practices for 5G antennas.

You say:

Question 11 concerns me for the already stated reason of antennas not supporting protocol but also for reasons relating to 5G. The question assumes that 5G only exists in the context of massive MIMO mm-wave. The objective of 5G is not just packing more antennas at a higher frequency into a single unit. It should also be noted that antenna design and placement is also agnostic of protocol.

Well, I took the question from this document from our sponsor: http://www.literature.molex.com/SQLImages/kelmscott/Molex/PDF_Images/987652-2034.PDF

I guess I don't read this question the same way that you do. I read it straightforward and in two parts: (part a) is it true or false that  5G wireless technology products will need to incorporate an array of high-frequency antennas into their products. ( part b) And, is it true or false that designers of 5G wireless technology products will need to determine antenna placement best practices for 5G antennas.

Are you saying either of these are false?   If so, which part?

It is a wide open question. I think that's why I asked it.  If anyone else has an thought about this, feel free to comment.

Finally, how would you reword the question?

Randall

element14 team

Question 4:

    Loop

    Helical

    Cave

    Microstep Patch

    Dipole

You say: I also have issues with the typos since technically question 4 has two correct answers.

Well, I made up the "cave" antenna. Just a product of my imagination. As such, it is not commonly used. What were the typos and the two correct answers?

Randall

element14

    True

    False

You said:

Question 21 assumes that the dipole length is fixed, Once the dipole length starts to increase it will no longer look like a donut.

The source of this question is here: https://www.sciencedirect.com/topics/computer-science/dipole-antenna

I agree with you that if you change the conditions (i.e., increasing length) the radiation pattern will change. But generally speaking, they have a donut shaped pattern. Perhaps I could have reworded the question: T or F: In general, the radiation pattern of a dipole antenna resembles a donut in 3D. Something like that.

I could have done a fill in the blank question: A dipole antenna's radiation pattern is often describes as  _______________.   (Answer: donut shaped.)  That's about all I was getting at with this question.

To precisely determine the shape, I would have had to provide a lot more information of course. And that would be a different  kind of question.

Randall

element14

Question 23:

    True

    False

You say:

Question 23: From the phrasing of question 23 it leads me to believe that the beamwidth of an antenna is symmetric. The antenna beamwidth is commonly defined in terms of 3dB, 10 dB, and first null beamwidth. The first null beamwidth is no longer on the main lobe. It would better to phrase the question in terms of amplitude since 'identical points' implies some level of symmetry.

This was a definition question. When I saw the word beamwidth in a glossary of an antenna handbook I was read, ingI thought it would be a good question. So, I just defined it as per the handbook. Not much more than that.

However, definitions are sometimes tricky to write. Perhaps this wasn't the best wording of the definition. How would you define it?

Randall

element14

Hi Randall,

We do read the question the same way.

Part A of the question is false. 5G wireless devices do not inherently need arrays nor to be high frequency. 5G operates from 600 MHz to 28.35 GHz so not all of it is 'high' frequency. 5G will also support SISO so there is no guarantee of an antenna array being used.

Part B makes it sound like 5G will have its own special antenna optimization process. Antenna placement optimization is an electromagnetics based process not a protocol based process. Technically part B is true but only for the fact that all RF designers will need to consider antenna placement. It isn't some special process that only applies to 5G.

I might rephrase the question as:

True or False: Designers of 5G wireless technology products will need to consider antenna placement best practices to maximize performance.

This phrasing removes the ambiguity of mm-wave and sub-6 GHz 5G bands. It also removes the assumption that all devices are going to have multiple antennas.

Cave is clearly the made up antenna.

Microstep antennas do not exist. I am guessing that it was a typo and was meant to be microstrip.

You addressed my concerns.

Removing the absolute condition of the question fixes it.