Electronics > RF, Microwave, Ham Radio

Options to measure frequencies beyond 6GHZ - LMX2594 15GHZ signal generator

(1/6) > >>

mehdi:
Hello.
I am building an RF signal generator based on TI's LMX2594 eval kit.
It generates up to 15GHZ, while my spectrum analyzers go up to 6GHZ.
I can only think of 2 options to be able to measure and check my signal generator's output above 6GHZ, with my tools:

1. Buy a spectrum analyzer: the problem is the price and size. I can't afford a new 10+GHZ device, and I don't have enough space for old devices like HP 8593e. The only realistic option in my budget (less than 3K) is a Signal Hound SA124B which covers up to 12.4GHZ which is fine for me, but I have doubts about the impact of its phase noise on my measurements. It has -80dBc/Hz on 10GHZ in 1KHZ offset.

2. Buy a down-converter to check the signals with my Signal Hound BB60D. I have found one https://www.lotussys.com/products/budc2g14g which solves my exact problem as a frequency extender for spectrum analyzers, but I have doubts about its conversion loss (~9dB at 10GHZ) and noise figure (~11dB at 10GHZ). I don't know whether these numbers are good or not, and what their impact on my measurements will be.

Now, there might be other options as well, that I have missed. And also, what are the pros and cons of the above options.
I'd appreciate some help here.

coppercone2:
I think the problem is going to be that you need more power to compensate for those problems.

buy both, pay twice, learn twice as much

if you own a SA and you wanna get your moneys worth from it, education wise, you end up owning the other thing you are describing too. its just like having a transistor to experiment on

for a signal generator, I would be surprised if there was a problem. for picking up a signal from an antenna then you have way less power to work with.

I assume you can put out like 0dbm at least. a signal from the air is going to be mad weak (even for a cell phone its often almost nothing)

you can lower noise, reduce losses, or increase signal strenght. since you have a generator hooked up by a coaxial cable, #3 is like way more practical for a lab source. that is like getting a bigger dish, or just turning up the output potentiometer, for a lab source

for instance, gps basically stops working at -160dbm. works good at -140. I think a useful lab source should do 10dbm, and then have an attenuator. there is no reason to reduce the power until you have to because it just makes everything more difficult.

infact your generator does 7dbm. That is like a ship horn compared to ant walking.

tszaboo:
You can rent one. I've rented 26GHz spectrum analyzers, and if you need it for a week, they are quite reasonable cost.
Though you might need to be a company to do that, discuss and negotiate with the rental company.

fant:
Good morning;

I am very interested about the generator; are you planning to provide it with modulations ( AM, FM, Digital?)

About the converter, I think it is easy to do it, with a 6 GHz generator and a mixer, you have the same attenuation (about 8-9 dB) and it cost much less.

Remember that the  spectrum is upside down.

Mandi

tggzzz:

--- Quote from: fant on September 10, 2023, 02:15:07 pm ---Good morning;

I am very interested about the generator; are you planning to provide it with modulations ( AM, FM, Digital?)

About the converter, I think it is easy to do it, with a 6 GHz generator and a mixer, you have the same attenuation (about 8-9 dB) and it cost much less.

Remember that the  spectrum is upside down.

Mandi

--- End quote ---

Compensating for attenuation in the instrumentation is easy and cheap.

Compensating for phase noise in any of the instrumentation is not easy and not cheap.

I too have a 2594 eval kit. I remember being surprised at how low its phase noise was at 15GHz. But, I only did quick and dirty experiments using an HP8562B and Tek492AP, haven't saved any results, and wouldn't feel justified in using them for anything more than amateur curiosity.

There was much more noise visible on the HP, including spikes visible at +-30kHz. I presume, without evidence, SMPS noise. The 492 display was much cleaner, for reasons I haven't investigated.

Navigation

[0] Message Index

[#] Next page