Antenna engineer interview questions

[PythonGuython]

What technical questions would you ask when interviewing a recent graduate for an antenna engineering position?

[coppercone2]

what alien race has the best looking ones?

[Bud]

What is the difference between antenna and antennae.

[Neomys Sapiens]

Now that is a position where I would be very loath to consider a recent graduate, as antenna engineering needs experience. The one thing that could help is if he/she were one of the few Hams (radio amateurs) that are really experimenting with antennas. Ask for design experience resulting in real builds, not mere EZNEC simulations. And ask for knowledge about materials engineering, as this will determine what happens to your antennas in real installations.

[LaserSteve]

I'd ask you some dB ratio puzzlers.

I'd ask you about the minimum VSWR
of a 75 Ohm coax in a 50 Ohm system if other
Elements are ideal.

S parameters.

Filters..

Baluns

KIPS / Forces in relation to tower bases and guys.

Ground planes, lightning protection. Regs, tower lighting.

Harmonic mixing and IM products.

S.O.L.T.  including lots of questions on what an
Open is , during VNA calibration.

I'd guage your ability to prototype.

I'd give you a rather comprehensive Navy guide
on HF and mid band antennas and their layout,  give you a pen, paper, and calculator, a task using the book and one paid hour to give me a layout and specs for a given desired tx/rx site in a network.

.

Not that it counts for much. But do you have any licenses?  That would be a direct question, as well as do you have a PE in the state you are working in.

Any serious mechanical hobbies or shop skills?

Then I would ask you about antennas.

Steve

[KE5FX]

I'd ask you some dB ratio puzzlers.

I'd ask you about the minimum VSWR
of a 75 Ohm coax in a 50 Ohm system if other
Elements are ideal.

That's a great question. 

Another is the old standby, "You've just done a 1-port calibration on your VNA, and your open standard is still connected.  What does the Smith Chart look like?"

[TheUnnamedNewbie]

Depends on the exact type of antenna engineering and what you expect of them.

If it is a recent graduate, I usually assume they know little of actual useful knowledge, and their education mostly provided them with the tools to learn and understand quickly (this ofcourse does depend on where you are, around here you don't have any antenna or RF focused educational programs, all are general electrical engineering with at best a focus on analog versus digital versus embedded).

So I would usually ask questions that I don't expect them to know the answer to, but instead can help them work towards an answer so I can see their process of reasoning, in this case focused on fields and RF stuff. Maybe something like

"You have an ideal, infinitely long transmission line of impedance Z0. At the end of the tranmission line you have a voltage dependent voltage source. You can place any passive network you want between the transmission line and the voltage source. What network will provide the highest output power from the VDVS?" Once they answer that, add conditions: "How does your answer change if the transmission line is of finite length? Are there any lengths that require extra attention? How does that answer change if the transmission line has loss? Does this new answer depend on how much loss it has?" etc etc.

In a lot of cases I'd rather have someone who can't (immediatly) tell me the right answer, but is clearly able to see the boundary conditions, sees how there might be tradeoffs, reason their way towards an answer, than someone who can just say 'the best solution is x'

Also maybe ask them a bit about fields. Draw a patch, ask them to scetch field distributions. Where is max votage/max current/what does this depend on.

[LaserSteve]

In my case, R6G out performed good RG-58.  I remember 1.22 to 1.3 to 1 on a known good VSWR meter.

Theory says 1.5 to 1. So tell me dear candidate,  assuming I'm
not fibbing, how that could have happened?

Steve

[jonpaul]

what is a rohmbic  antenna, sketch a 30 m band design with dimensions.
find the gain 30 deg off axis,  of a 10 éléments yagi, for the aircraft tower  VHF band
Sketch  a block Description for,phased array x band radar system for missiles detection
Approximately how many,éléments to achieve a 1 degree beam width?
What is the chaff size for a k band radar ?
Usual polarization of . antenna for...FM broadcast? 2.4, 5 ghz cellular? Airport NDB? Airport VOR?

Answers anyone?

jon

[Psi]

What technical questions would you ask when interviewing a recent graduate for an antenna engineering position?

Sounds like a good question for chatGPT   (with appropriate checking/oversight)

[coppercone2]

Answers anyone?

jon

hyperagile III with a focus on cost and synergy with time to market

[PythonGuython]

If you just calibrated your port, the smith chart should read along the resistive axis near the right side, near infinity.

How did I do? Am I missing practical effects - don't opens sometimes read slightly capacitive?

[PythonGuython]

"You have an ideal, infinitely long transmission line of impedance Z0. At the end of the transmission line you have a voltage dependent voltage source. You can place any passive network you want between the transmission line and the voltage source. What network will provide the highest output power from the VDVS?" Once they answer that, add conditions: "How does your answer change if the transmission line is of finite length? Are there any lengths that require extra attention? How does that answer change if the transmission line has loss? Does this new answer depend on how much loss it has?"

Without setting up specific parameters of this problem, how would you reason about this? The only concepts that come to mind are opens and shorts can appear as inductive or capacitive depending on the length of the line relative to the wavelength, but I don't know how the VDVS affects that... Then the other concept is max power transfer when your source and load impedance are matched with the complex conjugate. What else am I missing?

[PythonGuython]

I'm sorry can you explain the test more? What is the DUT here?

[Bud]

If you just calibrated your port, the smith chart should read along the resistive axis near the right side, near infinity.

How did I do? Am I missing practical effects - don't opens sometimes read slightly capacitive?

Not "slightly" capacitive to be pedantic, but exact capacitance of the Open standard which you entered in Cal Standards Coefficients settings of the VNA, if the VNA has that feature. If there is no calibration standards coefficients entry in the VNA, as it may be with cheap or some handheld models, the VNA assumes the Open standard is ideal with no capacitance, and will display the Open as a dot on the righthand side of the Smith chart R axis.

[TheUnnamedNewbie]

"You have an ideal, infinitely long transmission line of impedance Z0. At the end of the transmission line you have a voltage dependent voltage source. You can place any passive network you want between the transmission line and the voltage source. What network will provide the highest output power from the VDVS?" Once they answer that, add conditions: "How does your answer change if the transmission line is of finite length? Are there any lengths that require extra attention? How does that answer change if the transmission line has loss? Does this new answer depend on how much loss it has?"

Without setting up specific parameters of this problem, how would you reason about this? The only concepts that come to mind are opens and shorts can appear as inductive or capacitive depending on the length of the line relative to the wavelength, but I don't know how the VDVS affects that... Then the other concept is max power transfer when your source and load impedance are matched with the complex conjugate. What else am I missing?

The entire point of this question isn't that there is a specific answer to this (I also just came up with this in a whim as example, I'm not saying I uses this a lot or anything). It's so the person I'm interviewing can reason and bounce ideas around what would impact this, etc. And there is the added trap that a rookie would just say 'a termination resistor equal to Zo', but that is not correct. For example, a transformer with ratio M and a termination of M^2*Zo would have M times higher voltage. And nothing stops you from taking that to the extreme with M->infinity.
The candidate might bring up reflections, or the fact that an open would give double the voltage.

[xabre77]

First five from ChatGPT:

What is the role of impedance matching in antenna design?
What are the main factors that affect antenna gain and how are they related?
What is the difference between a directional and an omnidirectional antenna?
What is polarization in the context of antenna design and how is it determined?
How do you optimize the performance of an antenna in terms of efficiency, bandwidth, and radiation pattern?

[n4u]

U should ask for somethink he needs in work. You didnt provided any information about software / hardware / types of antennas you are making / measures etc.
Let him make some measurement in VNA (with calibration) / spectrum analizer / ask him about S matrix / reflection coef / characteristics of standard antennas / matching circuits / let him make some sim / ask what he ever done / give him some impedance and let him match it using rg58 for some freq, then change the freq and ask him to make planar match / you maky ask about planar circuts /or antennas

[Joel_Dunsmore]

Tell me about your last antenna project, be specific, give examples.

[tggzzz]

What technical questions would you ask when interviewing a recent graduate for an antenna engineering position?

If you don't know what questions to ask

• you probably don't know enough to be able to evaluate the answers
• you won't be able to formulate follow-up questions on the fly

[pdenisowski]

As many others have said, designing antennas is part art, part science, and usually requires quite a bit of experience and equipment to do properly.  I wouldn't expect many new grads to have much of either.

What I would expect of a new grad interested in an antenna design position are things like:

- How to use / read a Smith chart
- How to make basic antenna measurements using a VNA
- Familiarity with some kind of modeling tool
- Some experience with matching / tuning networks
- Knowledge of basic antenna types and concepts (dipole, Yagi, LP, relationship between beamwidth, bandwidth, phasing of multiple antennas, effect of environment on antennas)
- Basic antenna construction / prototyping techniques
- Ideally, a genuine interest in antenna design (i.e. someone who plays with antennas as a hobby, not just in classes / labs)

[n4u]

what you can do with a meter of rg58 cable

[Mr Simpleton]

"Seriously Sir, are your name really Ant Luneburg? "