Aardvark Daily

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I have a new toy

The great thing about electronic gadgets is that as time passes, almost everything gets cheaper, smaller, faster and better.

When I think back to how much a half-decent TV set used to cost, in the days of CRTs, I tremble in shock. I seem to recall paying well over a thousand dollars for a semi-good Sony Trinitron TV set back in the 1990s and that was only about a 21-inch screen with paltry SD resolution.

Fast-forward to 2023 and you can pick up a 55-inch 4K flat-screen set for as little as $500 of today's dollars.

Today's TV set is better in every way. Higher resolution, more accurate colours, lower power consumption, over four-times the screen area, etc, etc.

When you move into the area of more specialist electronics, things sometimes move even more quickly.

One needs only look at my new to, a Vector Network Analyzer (VNA) to see just how rapid the pace of change can be.

What is a VNA?

It's an electronic device that is used to characterise and measure many aspects of radio frequency circuits. Most often it's used to make measurements of antennas.

This isn't a device that many people would want or might have any use for but it's something I've been lusting after for a very long time.

I've always had an interest in radio-frequency stuff, ever since I built my first crystal set AM receiver when I was about six or seven years old. It still amazes me that we can pluck ripples of electromagnetic energy out of the ether and amplify them sufficiently to enable the transmission and reception of music, voice, digital data and a whole bunch of other stuff. Crucial to such things are antennas.

These days, thanks to computers, it's pretty simple to sit down and design an antenna for a particular frequency that has the characteristics you're after. High gain for longer distances, directional to minimise interference, omnidirectional to get all-around coverage, etc, etc. The problem is that you can never be 100 percent sure that the theory produces the practical results you're seeking.

For example, most antennas are designed to operate over a specific range of frequencies. If you make a mistake in the calculations or there are inaccuracies in the construction then the actual frequency may be far enough away from the desired frequency to cause issues. The only way to know for sure is to use a VNA to measure the parameters of what you've built.

VNAs have, due to their complexity and relatively small market, always been hugely expensive. Prices from $10K for a second-hand one to more than $30K for a new one were not out of the norm.

Obviously that's way beyond sensible for someone who isn't able to recover that cost through the use of such a device.

For that reason, VNAs were normally only found in professional environments and rarely seen in the hobbyist world.

That all changed a few years ago though.

Advances in electronics technology have made low-cost VNAs a reality and I bought one from Ali Express in China for just a couple of hundred dollars.

What the?

Okay, this isn't a professional-level device with a certified calibration sticker on it, far from it. However, it is more than adequate for the type of things I want to do and at two orders of magnitude less money than something from Keysight it is perfectly affordable.

It's also small... pocket-sized and runs from an internal rechargeable battery.

I spent a few hours playing around and getting familiar with it yesterday and I have to say I am gobsmackingly impressed with its capabilities -- it even has an upper frequencly limit of more than 6 GHz.

It's not perfect by any means and of course I'd still love a big-name unit which can be relied on to produce absolute rather than relative data but hey, for the money this thing is astounding.

Having characterised a few of my home-built antennas I'm pretty happy with their performance but I've already spotted ways in which I can improve them so that's going to be a whole lot of fun now that the weather is warming up and I can test those improvements in very practical ways on my FPV drones.

The wife can spend her time watching that 55-inch screen in the living room, I'm far more captivated by this 4-inch LCD with all its numbers and wavy lines.

Carpe Diem folks!

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