Seb Holzapfel

11 posts

Beginnings of a cheap 2-14GHz Mixer

Recently I've been working on a project for which I needed a 14GHz double-balanced mixer, however I'm on an extremely tight budget.

Luckily, most manufacturers provide free silicon samples these days, and Linear Tech (or rather, Analog Devices these days) is no exception. The LTC5548 is a pretty awesome MMIC, DC-6GHz IF, 1-12GHz LO, and 2-14GHz RF. It also includes a buffer so that you can use LO powers around the 0dBm mark instead of an ordinary mixer which might require.

Unfortunately, the evaluation board for the chip costs hundreds of dollars (~$300!) and I need multiple for my experiments.

Read the rest...

Analyzing the ugliest filter

Or perhaps 'How to make a microwave filter for $0'. Yesterday afternoon I wanted a 1.2GHz filter for an experiment, didn't need anything super-performant, and didn't want to spend any money. Before I actually show you what the filter looks like (because it's hilariously ugly), here's it's response (0-2GHz sweep):
Okay, the frequency response isn't so bad, but I'm putting -10dBm in so we've got about 10dB of insertion loss which isn't great. 300-600MHz seems to seep through at around -40dBc, which is surprisingly not bad. Here's the setup:
So you can see from the tuning scale that the

Read the rest...

Website update!

Alright; I've been sitting on the same old website theme for the last couple of years, so I figured it's about time to change...

Been sitting on this for a couple of weeks and slowly migrating all of my old content over. I think I've fixed most things now; so this new site's now live!

I've completely changed tech and moved over to the much sexier (in my opinion) Ghost blogging engine, with a heavily modified version of it's normal themes with some alterations to allow for my static content.

Annoyingly I couldn't import any of the comments from my

Read the rest...