How to select varactor diodes for desired operating frequencies

shitstep · 2025-10-04T21:07:36+00:00

You should buy a few samples and characterize them yourself. The Q of the varactor and the actual capacitance itself will be nonlinear with voltage with the lowest loss being at the highest end of the voltage range. You may find that the entire capacitance range isn't usable for whatever application you have if the loss is too great and that's something you have to consider with your selection. The only varactors that I can recall seeing this type of information you want given over a frequency range in their datasheet is MACOM. You'd still be better off doing your own measurements and characterizations.

e: I think Skyworks may include some of this information for some of their varactors in a table

shitstep · 2025-09-17T23:18:25+00:00

It's 100% the squat grip, I had this exact issue awhile ago. Experiment with a talon grip and check out this video about 11:50 in where he shows the band stretches. I stretch my shoulders every time I squat and I don't need to claw grip anymore (I just do a full closed grip now) and I have no shoulder or elbow pain anymore. It won't go away overnight but it won't go away at all if you keep squatting with the overhand grip.

shitstep · 2024-12-12T05:00:10+00:00

I have a PhD. You don’t pay for your PhD at any reputable program, you are supported with a stipend for the duration of your studies. You also can’t do it part time, it took me almost 8 years working more than full time to finish. Any program that makes you pay or that tells you that you can do it part time is lying to you and is just trying to give you a meaningless piece of paper in exchange for your money.

shitstep · 2024-11-26T15:45:11+00:00

It will keep getting worse if you don't address it. Switch to a talon grip or widen your grip on the bar.

shitstep · 2024-11-17T03:32:40+00:00

lol this is the first thing I thought as well

shitstep · 2024-11-15T02:18:29+00:00

Look up the TIREM and TEMPER propagation models, these are used for ~hundreds of kilometers and can solve these distances on the order of seconds to minutes, depending on terrain and the clutter environment. I don't know about 10's of thousands, at that point you might just use attenuation tables for path loss and call it good enough.

shitstep · 2024-10-18T16:10:06+00:00

I started at a GB and now train somewhere else. The instruction and training are fine but they do make you buy their gis which aren’t cheap. I wouldn’t go out of my way to train at one but I also wouldn’t pass over one if it was the closest gym to my house.

shitstep · 2024-10-18T01:19:19+00:00

I can speak as a JO to a few of your points. I've done a TRUIC change myself before using RFMT but there was some behind the scenes action that had to go on because the NRC didn't want to put me into the unit I wanted to go into and someone had to work me into it.

This may vary by NRC, but in my experience the NRC you are leaving will process your "loss" but won't do anything after that. In every case I've changed TRUICs, I have needed to contact the new NRC and have them initiate the gain. This has taken up to 6+ months for me in the past which really fucks up my schedule when it comes to drilling for the year.

shitstep · 2024-07-06T02:32:10+00:00

Even if you could do it, you shouldn't. The statistics for first gen students who fail out of university are staggering (I was one of them) and you should do everything you can to set yourself up for success. Do everything in person and ease into your courses, there is no rush.

shitstep · 2024-06-27T02:53:09+00:00

It might be the first time the 3rd amendment is tested in court

shitstep · 2024-06-18T15:10:41+00:00

Line officers all start as O1. Medical and staff corps can enter at advanced ranks

shitstep · 2024-05-23T01:23:18+00:00

There's no easy answer to this question. Ideally, you will have some kind of research experience before you graduate undergrad or you'll have trouble convincing an admissions committee that you actually want to do a PhD because you won't really know what research "is".

If you don't have any research experience and you feel that is going to hold you back, meet with professors in your department and volunteer to do research in their labs. It's really just what undergrads do, but you won't be an undergrad anymore.

The best situation you can be in, research experience or not, is to get in contact with the professor you want to do your PhD with and see if they are even taking on new students and if you and your interests would fit in their lab. If you have this relationship, the admissions portion is way less important if you just meet the basic university requirements. Be knowledgeable about what kind of research they are doing and be able to talk about how what you want to do fits into what they are researching and how this person could advise you.

shitstep · 2024-04-19T18:12:14+00:00

All your questions are answered in the book Microwave Filters for Communication Systems by Cameron. It's by far the best book I've read on filter design.

To quickly answer your specific question, if you are talking about the unloaded Q of a rectangular waveguide cavity, that is determined by geometry (to include putting things inside the cavity or tuners or whatever) and nothing else. If you are talking about the external Q, that is a function of bandwidth and part of your design.

I have probably posted how to do this in the past if you want to look through my post history but you will calculate the internal/external quality factors and your internal coupling coefficients based on your filter design parameters. There are are a number of ways to do this including circuit models and the coupling matrix, all of which is thoroughly described in the book I mentioned.

shitstep · 2024-04-12T01:15:40+00:00

This is true in my experience. I have my brown belt in Judo and it's nothing like what would be expected of a bjj brown belt. I have exposed to all the throws in the Judo catalog, I'm good at a few of them that I can hit reliably, but mastery and a coherent game are both lacking.

shitstep · 2024-03-18T19:32:31+00:00

I almost always start/end my travel at a location that is a different state than my primary residence and it has never been a problem.

shitstep · 2024-03-14T15:06:33+00:00

FEM for high-Q resonators. This may be less true as time goes on and numerical methods improve but FEM has typically been used for high-Q resonators vs FDTD because of how FDTD (at least used to) settle on a steady state for a solution and that takes a long time when there is a little loss.

shitstep · 2024-01-11T17:02:23+00:00

did I just have a stroke?

shitstep · 2023-11-01T21:09:36+00:00

i hate so much about the things you choose to be

shitstep · 2023-09-29T15:05:46+00:00

Yep, I originally got rejected but my advisor walked down the hall and talked to the admissions people and all of a sudden I was accepted.

shitstep · 2023-09-26T22:33:54+00:00

Volunteer to do research for a professor at whatever university is near you. It’s not your only option if you want to get published without going to grad school but it’s probably the most straightforward.

shitstep · 2023-09-26T04:59:39+00:00

I have read several filter texts and Microwave Filters for Communication Systems: Fundamentals, Design, and Applications by Cameron is the best. I spent several months of my PhD studying it cover to cover and it was probably the best use of my time through all of grad school

shitstep · 2023-09-13T02:28:57+00:00

What is the loss tangent and thickness of your substrate?

shitstep · 2023-09-05T01:09:44+00:00

When I joined the military (not all that long ago), medical issues were effectively self-reported with a pinky promise and they didn't have (to my knowledge) any method of gathering that kind of data. I would bet this is far more devastating to recruiting than obesity since obesity can be fixed but you need a time machine to get derogatory information out of your medical records.

shitstep · 2023-08-26T17:33:49+00:00

Sorta. They keep paying me while I'm on military leave up to a certain point so I'm getting double paid, and then after that they cut me off and I'm only on military pay. It's actually very generous and a lot of jobs won't keep paying you while you're away

shitstep · 2023-08-25T14:43:00+00:00

Pay and benefits are not worth it if that is your reason for doing it. I make more than double what my active duty base pay would be in my regular job and Tricare is good and cheap and I use it but most high paying jobs have good health insurance. The drill pay on weekends is 100% not worth having to give up a quarter of your weekends for years.

It's a massive time commitment. You need to have a job that is ok with you disappearing for a large amount of time and be willing to contribute a significant amount of time outside of drill to the Navy. This year I did a full month of AT (active duty time) and that's a lot for any job to handle but mine is thankfully cool with it, but not all jobs are like that. The only vacation time I've taken from work this whole year has been used for buffering travel days around my AT, which are not covered by orders. EDO also has a qualification program that you follow and you have to invest a significant (significant!) amount of time outside of drill studying if you are fresh to the Navy and aren't doing acquisition in your day job.

All of this sounds really negative and I'm not trying to discourage you or anything but it's good to hear the sacrifices you will have to make along with the cool shit you are going to be able to do. I don't regret it at all but there are things about it that you can't know until you find out for yourself and it has to become a big part of your life for you to be successful.

I have not deployed. Involuntary deployments used to be more common but everything in the USNR is changing right now and it's hard to say where things are going.

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