This site shows a used one for $250

http://www.aptecelectronics.com/WR-42.htm

Good luck!

Steve

By the definition of bandwidth, you can get 200%, in theory, but that would take a low-pass filter! It is just a convention.

If you have 10 GHz bandwidth centered at 8 GHz, you have 125%.
Steve

I think that the Millitech product line either originated at Hughes, or used Hughes diodes.

I found an old Hughes mmw catalog here

http://www.dudleylab.com/hughes%20mmwave%20products.pdf

Gunn diodes are on page 76

Maybe 17 means 170 mW?

Maybe searching on Hughes will help. Or contact Eravant... a competitor might know about this.

Good luck

Steve

I agree about recommending MWO, been using it for nine years. All good except the VSS product still confuses me, so I am gonna try out Genesys.

Have you looked at Microwave Office with Axiem? I was forced to switch from ADS, nine years ago, now I don't want to go back. It may be cheaper; I don;t get involved with pricing.

Does anyone have an opinion on what the best shareware is for a retired microwave engineer? Asking for a friend...

Steve

I have run into dispersion in coax, at low frequency. It has to do with skin attenuation, but my math skills are so rusty I gave up on solving for it. I started to write a page on it here:

https://www.microwaves101.com/encyclopedias/low-frequency-dispersion-in-tem-lines

Just remember, at low frequency, lines get electrically longer!

It is interesting that in Microwave Office this effect is NOT modeled in the coax circuit element. But it IS modeled in the stripline element! So you can fake a coax design with the stripline model if you don;t go to far outside the limits of the relative thickness of the strip versus ground plane spacing.

Once the center conductor diameter is large compared to skin depth the problem dies down quickly. Virtually every design above 1 GHz can ignore coax dispersion. The real killer will be at higher frequencies where the coax starts an unwanted mode.

https://www.microwaves101.com/encyclopedias/coax#TE11

Steve

We are going to need some expert help here... I have exhausted my limited knowledge of sources. My guess is that this is done in the digital domain, it would be hard to maintain 1 degree resolution using analog networks.

Where are all the smart people out there when you need them....

Steve

Weird that it was there for free

I downloaded a copy. One of these days I will try to organize some more material properties stuff and post...

Steve

Glyn

Grateful for the correction! Not sure where that incorrect data came from. Possibly the Tanqueray bottle...

Here is a page that shows RuO2 as well:

http://www.resistorguide.com/thin-and-thick-film/

We updated the page:

https://www.microwaves101.com/encyclopedias/thick-film-resistors

Send corrections any time, and let my know if you want to receive a Microwaves101 gift for your troubles...

Steve

I know people that have ordered thin film parts from US Microwaves. Never heard any complaints. It is a small company, their web site/phone system are probably not big priorities. Someone might want to forward this message to them...

Steve

JPD

This topic has not been dealt with very well on Microwaves101, our apologies! People tend to write textbooks about what they know, and I never really had to work on a source.

Modern sources use voltage controlled oscillators and phase-locked loops, with the output usually below 6 GHz. Then, mixers, multipliers or other nonlinear devices are used to achieve higher frequencies.

Bandwidth in a VCO is limited, maybe an octave. So for wideband, you will need more than one VCO, or more than one multipler, and then somehow mux it all together. Here's an example from Analog Devices

https://www.analog.com/en/products/adf4371.html

I am hopeful that someone smarter than I will add to this answer!

Steve (the Unknown Editor)

RF Cafe has some dielectric data here

http://www.rfcafe.com/references/electrical/dielectric-constants-strengths.htm

unfortunately, you know how these free web sites are... no reference provided!

I used to know an antenna guy that kept a loose-leaf notebook with every pages of stuff he had printed out on any material he ever found. I regret that I did not borrow it and spend an evening at the xerox machine...

jmcghee... any possibility you could sketch that out?

Also, is it possible to add a bandpass filter that is designed so that it makes it "nearly impossible" to present an unstable load to the part? Maybe the unstable region is on the open side of the Smith Chart, and you make sure that the device sees a short circuit. I have never analyzed this, maybe you can't get there without some real resistance.

Thanks!

1) ignore matching the output to 50 ohms... just match to the ZL that gives best performance. Not that ZL for max efficiency is not the same as ZL for max power. It is a compromise.

3) There are papers on harmonic terminations... I am no expert. But it is correct that high impedance is required. At first harmonic, you might want a short circuit. This could be done with an open stub close to the FET that is quarterwave at 2F0. Nothing that you add to the matching network after a short circuit will change the termination impedance at 2F0. At F0, it will look like a capacitive stub that you can work into the output matching network, and get to your load-pull match. The power amp will perform much better if you take care of that second harmonic. Dealing with the third harmonic is probably a lot harder and will have diminishing returns. Like "milking mice" as my old boss used to say...

I hope this helps

Steve

I took a fast look at that FET but could not stabilize it in the ten minutes I spent, without messing up the minimum noise figure. I hope to mess with it later, I don;t like it when instability wins.

Does anyone have any experience with balanced LNAs? A friend of mine claims that almost automatically stabilizes the circuit but I am skeptical.

Steve

This is a really cool system, I wish I had time on my hands to make one. You can imagine the fiber optic cables getting tangled up. An opportunity for someone to develop a rotary joint to bring out the data, to a blue-tooth arrangement outside the oven. Or maybe tiny sensors inside that send out data through the door at 94 GHz?

Hopefully, one of you reading this can point to a company that already markets such a product.

I am at a small company, we have shied away from low temperature testing. One problem is condensation, which can affect measurement accuracy or in worst-case destroy hardware. Temperature chambers are better suited compared to platforms in my opinion. The chamber design should pay attention to how to maintain zero humidity inside. Is this available?

Another thing I once encountered was near asphyxiation in a lab that had a large number of temperature chambers using N2. It makes you very sleepy, as opposed to speeding up your heart like CO2 chambers do. It seems like very few labs have N2 concentration sensors

https://en.gazdetect.com/gas-information/nitrogen-gas-detector-n2/

I have read at least one published paper on positive feedback in the second stage of an LNA. Not sure if this is the article, I don't have ieeexoplore access, but the title sounds useful...

https://ieeexplore.ieee.org/document/5161354

I used the technique and convinced myself I could get one dB more gain beyond MSG. I left the company before the chips came out so I never saw the data...

Thanks for the design notes!

Steve

I believe you should use lambda guide, as described here

https://www.microwaves101.com/encyclopedias/waveguide-mathematics

But I would hold out for a second opinion!

Steve

Just curious, how do you know the field is non-uniform? is this a series cap or a shunt cap?

10cm is ~7% of a wavelength, 24 electrical degrees, I think there should not be much of a distributed effect. but you could try two 5cm line/pairs in parallel.... or five 2.5cm lines that have four uniform gaps...

Steve