Waveguide Ventilation Plates

How We CNC Machine Waveguide Array Ventilation Plates – It's Not Fast and It's Not Cheap

Most shielding vents are honeycomb. Thin foil. Stack it. Braze it. Fast. Cheap.

Waveguide array ventilation plates are different. No foil. No brazing. We start with a solid block of metal. Then we drill a million holes straight through.

It's slower. It costs more. But at high frequencies, it works way better.

Here's how we do it on our shop floor.

Why Bother with CNC?

Regular honeycomb has seams. Brazed joints. Cell walls that aren't perfectly straight. At 1 GHz? Fine. At 5 or 10 GHz? RF finds the gaps.

A waveguide array is one solid piece. No seams. No joints. Just a block of metal with straight holes. That's why it shields better at microwave.

But it's a pain to make.

Step 1 – Get a Thick Plate

We buy solid plate. Aluminum or stainless. Thickness is your vent depth – 1/2 inch, 1 inch, whatever.

Cut it to size on a bandsaw. Then face it on the mill to make it flat. If the plate is warped, the holes won't be straight.

Step 2 – Drill Hundreds or Thousands of Holes

This takes forever.

We load a program into the CNC. It tells the machine where to drill – a grid of holes. 1/8‑inch spacing. 1/16‑inch spacing. Depends on the spec.

Then the machine drills. Hole after hole after hole.

A 12x12 plate with 1/16‑inch holes? That's about 9,000 holes. Each hole takes a second or two. Plus moving between holes. Plus changing tools when they break.

You're looking at 2-3 hours of machining for one plate. Sometimes more.

That's why these things are expensive.

Step 3 – Clean Up the Burrs

After drilling, the plate is sharp as hell. Burrs on both sides.

We run it through a deburring machine. Or hand‑deburr with a tool. Then a quick pass with a file.

Then wash it. Coolant and metal chips need to come off. Parts washer, compressed air, done.

Step 4 – Add a Frame and Gasket

Some plates are just the drilled block. Others get a frame for mounting.

We can machine the frame from the same block – leave a solid border. Strong, but wastes material. Or we can make a separate frame and bolt or bond the array into it.

Then stick on a conductive gasket. Silver‑filled silicone or beryllium copper. By hand.

Step 5 – Test the Damn Thing

Every batch gets tested. We put it in a fixture with a spectrum analyzer. Measure shielding at 1, 5, 10 GHz, as high as the customer needs.

Also measure pressure drop. Airflow is usually the same as honeycomb with the same open area. Sometimes a little worse because the holes are straight, not flared.

Why the High Price

Solid block costs more than foil.

CNC time costs money – 2-3 hours per plate, not 2 minutes.

Drills break, especially in stainless.

Deburring and cleaning take labor.

Honeycomb vent – $50 to $100.

Waveguide array of the same size – $300 to $600 or more.

But if you need 60 dB at 10 GHz, honeycomb won't get you there. So you pay.

Real Job – 6 GHz Requirement

Customer needed 50 dB at 6 GHz. Tried honeycomb – got 30 dB. Not enough.

We made an aluminum waveguide array, 1/8‑inch holes, 1/2‑inch thick. CNC drilled. Tested at 6 GHz – 55 dB. Cost $400. Honeycomb was $80. Worth it for them.

Real Job – Radar on the Coast

Another customer. Radar at 9 GHz. Outdoor, near salt water. Honeycomb wouldn't shield and would corrode.

We made a stainless waveguide array. 1/16‑inch holes, 1‑inch thick. CNC drilling took two shifts. Price was $1,200. But it lasted. That's what mattered.

When You Don't Need CNC

Frequency under 3 GHz? Honeycomb is fine. Don't waste money.

Tight budget? Honeycomb.

Weight critical? Honeycomb is lighter.

CNC machining is how we make waveguide array ventilation plates that actually work at high frequencies. Solid block. Straight holes. No leaks.

Slow. Expensive. Worth it when you need real shielding.

We do both. Honeycomb and CNC. Tell us your frequency. We'll tell you which one makes sense. No upsell. Just what works.