Microwave Waveguide Cover

Where is it ?


Inside the oven cavity, usually on the right hand side or in the roof you will usually see a small cover that looks like it is made of cardboard. It is often held in by one or more screws.

What is it ?  

It is called the waveguide cover. It is usually made of a material called Mica.

What does it do ?

Its purpose is to cover the aperture through which the microwaves enter the oven cavity from where they are produced by the Magnetron behind the control panel. It stops moisture and food particles getting into the “workings” of the microwave.

waveguide cover

waveguide cover

What do I need to know ?

if your microwave is working ok and behaving itself then there is nothing to worry about, but there may be one of 3 problems that may arise which should be rectified.

1. Its fallen off.

2. It has a hole in it.

3. It is arcing or sparking during use.

In any eventuality it should be replaced. If it has fallen off or got a hole in it then there is the risk of food or moisture getting into the waveguide which will reduce the efficiency of the oven. If it is arcing or sparking then continued use will damage other components in the microwave including the oven cavity which could be costly to rectify.

What should I do ?If there are any issues with your waveguide cover it should be replaced. When new the mica sheet is rigid and firm. Over a period of time it absorbs moisture and gets food splatters on it. It then becomes soft and flexible. The cover can be replaced either with a suitable replacement made by the manufacturer of the microwave or if the old cover is in good enough shape to be used as a template, blank sheets of mica can be purchased and cut to fit.

waveguide cover material - mica sheets

waveguide cover material - mica sheets

We often replace waveguide covers in our workshop. We are also asked to supply them directly. They are available mail order via our website ready made for some of the leading manufacturers or as blank sheets to make your own.

About microwaveexpert

The Microwave Service Company is based in Sellindge, Kent and provides repairs to Domestic and Commercial Microwave Ovens including 24 volt Samsung Roadmate microwaves.
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71 Responses to Microwave Waveguide Cover

  1. Mr. K K Yeung says:

    What would it cost to have a replacement waveguide cover for my Panasonic NN-MX26WF microwave oven sent by air to me in Hong Kong?

    Grateful for your advice.


    KK Yeung

    • Thank you for your enquiry. I would not be able to supply the correct part, however we do supply a blank pice of waveguide cover material called Mica sheet, with instructions of how to make one to fit. If you can copy and paste this link to that item on our website you can add it to your basket, follow throuogh the order process and get a cost to have it delivered, before you commit.


      We look forward to receiving your order.

      • mike mcdavitt says:

        Hi, I was cooking my food in the microwave and I realized the a corner piece was missing from the wave guide after I ate my food! Will this cause any harm?

      • No. see my earlier about damaged waveguide cover. If you ate it and didnt notice then it will probably break down and and you will pass it normally. The oven will be ok. Please see my earlier reply to a similar question.

      • mike mcdavitt says:

        I seen the earlier ine. But I guess what I’m trying to ask is sense a piece of the waveguide cover was off in side off the microwave . Will the light put off and thing that can harm you? Because don’t the waveguide protect your from the direct light from the hole in the microwave? And thanks for the help

      • mike mcdavitt says:

        Meant food

  2. TallTree says:

    While cleaning the splattered food off the waveguide cover in my microwave I noticed that a reflective material was coming off the waveguide. Is this stuff toxic or dangerous?

    The waveguide appears to be in good shape after the cleaning and the arcing is gone when running the unit.

    • Thank you for your comment. The waveguide cover is made of a material called Mica. When the cover is new it is rigid and smooth. As the cover ages and absorbs moisture in the oven it starts to flake and becomes very soft and fragile. The flakes you see are pieces of Mica flaking off. They are not toxic and arent dangerous in that they will be soft and won’t harm if ingested even ! Even if still intact, it would be agood idea to source a replacement waveguide cover. We do have pre made waveguide covers and also blank sheets of mica material for sale on our website. Unfortunatel I cannot work out how to add links to replies to comments so i shall do a new blogpost with those links in for now.

  3. TallTree says:

    When I say waveguide I really mean the cover.

  4. Steve says:

    I’m looking to replace the wave guide cover on an Emerson MW8168B. I see the part is no longer available at the part websites. I plan on fabbing my own from a blank mica sheet. The question I have is that there are no screws to back out but little white button tabs. I have pried on these and they don’t come out to no avail.


  5. mel says:

    If the waveguide has fallen off, and the microwave has been used, is there a health risk to my family and myself?

    • No there would be no helath risk, The cover covers the aperture through which the microwaves enter the oven cavity from where they are produced behind the control panel. The principle aim of the cover is to prevent moisture and food getting back into the workings of the oven. There will be no harm done to yourself in using the oven without this cover. It would be advisable to replace it sooner rather than later. If components inside get food or moisture on them, it wont do them much good.
      If you cant get the correct waveguide cover for your oven you can make one using the blank mica sheet, this available from our online shop.

  6. Lucy says:

    There is a dent/crease in centre of the cardboard-like waveguide cover. Should it be replaced or can I still use it as there is no hole in the cover?

    • Hi Lucy,
      The main purpose of the Mica waveguide cover is prevent moisture and food splatters getting back into the ‘workings’ of the oven. if your cover is intact it will be ok, I would expect it to degrade further as time goes on, it might be a good time to start thinking about replacing it though. We do sell blank sheets of mica from which you can make a replacement the same shape as your original.

  7. Karen says:

    Hi I have ordered a new waveguide cover for my microwave as it broke in two while cleaning it however we are on holiday using the microwave in our motorhome can I temporarily tape it together with scotch tape until I get home?

    • You can try it. You wont know until you try using the oven whether the scotch tape is invisible to microwaves. If it starts arcing or melts then may cause more damage. It would probably be better to use the oven without the waveguide cover until your replacement arrives. At least it wont cause further damage to the oven in the short term.

  8. Tamara says:

    My waveguide cover looks like it has some burn spots and does not come clean. Is this a sign that something is wrong? My last microwave started to smoke and the waveguide cover burned right through. Because of this I’m a bit cautious. Thank you.

  9. Theresa Branch says:

    I need to replace wave guide it sparks when i turned it on i clraned it and it still do the same can i put paper cover over it like the web page said

    • You would need to get the correct Mica cover, either from the manufacturer or we sell the blank mica sheet. You can cut this to shape and make a new cover if necessary.
      Please follow the link below to that section.

  10. fadia mahamid says:

    good evening , today i bought a new microwave . There was a waveguide inside it. My husband and I thought it isn’t necessary and we threw it away. After i read this article i know how it is important to the microwave…..what can i do? I will be grateful for your help……

  11. Ellen says:

    Microwave waveguide is damaged, manufacturered one no longer available so I need to make a new one, my question is that it has a fan like blade attached to inside of board. Is it safe to (if possible) punch hole to attached fan blade to new cut one.

    • It will probably be a difficult job to change that part over. I think from your description that the fan type blade might be used to better distribute the microwaves around the oven cavity. If you operate the oven without the cover and blade in place and see what happens. See whether the contents cook evenly. If the results aren’t too bad you would be ok to make a new cover and leave off the fan part. If the food doesn’t cook very evenly then it is obviously doing a good job and you will have to decide whether to get an engineer to make the correct part for you or to write off the oven.

  12. Christina modequillo says:

    Where can i buy a wave guide cover..?? And how much ??

  13. Someone says:

    Recently bought new microwave, mistakenly removed waveguide cover not realizing what it was. I can reinsert just slides into preset slots. Thing is I do not remember which direction the cover faced. Both sides seem similar, is there a right/wrong direction for it to face? Noticed one side had almost a small black mark if that helps.

  14. What’s up, all is going sound here and ofcourse every one is sharing facts, that’s genuinely good,
    keep up writing.

  15. Johnathan says:

    Hi i accidentally ripped the wave guide thinking it was a piece of cardboard on a new microwave (pretty dumb of me) is it still okay to use? The rip is about half the piece.

  16. miss L says:

    Hi I was wondering if you can replace the waveguide cover in a homemaker 20L microwave model EM720CPI
    And if so where can I buy the mica sheet from and how much

  17. Yours is not the only site that claims that the waveguide cover is just to keep stuff out of the waveguide. But what still then puzzles me is: why mica? It is most well known for having a really high dielectric constant, presumably even at microwave frequencies. But this would cause reflection of microwaves back into the waveguide, which could complicated power transfer. I am certainly not aware of any physical properties of mica that make it particularly good for keeping food-splatter out of the waveguide. Why not use plastic?

    • Interesting. Wave guide covers used to be made of plastic. We used to find that often they would become distorted. There is a tendency for the cover to get spots of food on which then get hot and cause the cover to melt. I suspect that the covers are now mica to reduce the likelihood of heat transfer. Mica has a greater tolerance to heat than most cheap plastics. Also if the cover does burn I don’t think it will catch fire if Mica. Certainly we have seen plastic covers that have resulted in cavity fires. Also there are a lot of grill or combi ovens around now. A mica sheet will be good for these too where as a plastic cover can only be used in a regular microwave appliance.

  18. Myra Pedrazzani says:

    i need a replacement cover waveguide for a rival microwave.

  19. netkom2 says:

    I only manage to get a 0.5mm mica sheet. I think my old cover is 0.3 mm. Can I use the 0.5mm sheet?

    • Yes. The thicker the better really. If it is thicker it should be stronger and last longer. The material is invisible to microwaves so should be unaffected by its thickness.

  20. Bob F says:

    Does the Mica sheet have to be cut EXACTLY like the guide being replaced or will it suffice to just have it cover the opening once it is cut to the basic rectangular size of the old guide?(the existing old guide has many angles, cutouts etc on it)
    Thank you!

    • It doesn’t have to be exact. It should be invisible to microwaves so in theory it wouldn’t matter what shape it was. It is designed to cover the aperture and prevent the ingress of food spatters so as long as it does that it should be ok. if you can try and smooth the edges so it doesn’t get caught by the dishcloth.

  21. C. M. Casas says:

    I need order mica for my oven to replace its old wave guide cover. However, the old cover did not have a screw but two tabs/flaps on each side that have to be inserted into four slots on the wall of the oven.
    In order to put the new cover I have to insert two tabs on one side first which is no problem. But then to insert the two tabs of the other side, the cover must be bent somewhat. As the new cover is brittle how could I bend it without breaking it?

    • You will need to bend it slightly in order to tuck the tabs in. There is of course a fine line between bending and breaking it ! In my experience if there are tabs at both ends, try and bend it in the middle and then tuck a bit of each end in first rather than fitting one end and struggling with the whole length of the tab when you try the other end.

  22. George Devine says:

    Hello, can you supply fixings for a toshiba ER-674 microwave wave guard cover ?



  23. Leo Tamim says:

    Hi, we bought a New Microwave oven. Before i learned about waveguide, i tried to see what behind of it and unfortunately it broken ( Not totally separated but just when a plane paper look like after folding) … will it cause any problem after all

  24. Me says:

    Hi, I saw the same question in the forum, but no answer, and the same thing happen to me.
    I mistakenly removed waveguide cover not realizing what it was. I can reinsert just slides into preset slots. Thing is I do not remember which direction the cover faced. Both sides seem similar, is there a right/wrong direction for it to face?

  25. Samsung ME73A says:

    How do I change the mica cover on a Samsung ME73A, can’t seem to fit it back into place, if I bend it I’l break it…

    • If it is made of cardboard looking MICA sheet it will be very rigid. There is a fine art in bending it just enough to tuck into the tabs and not breaking it. If possible bend it in the middle so that there is a greater distance to the edge so the bend can be less.

  26. Nan Burch says:

    How and where can I order a mic sheet so I can cut out my own wave guard for our microwave oven?

  27. Karen Weaver says:

    I have a whirlpool Mh7140xfb0 microwave. Our waveguide is broken. We cannot find any replacement parts. We are willing to attempt making one out of mica sheets but we have only found them in 5″x5″ sheets and our wave guide is 5 3/4 x 5 1/8. Do you have a part or a larger mica sheet?

  28. Dawn says:

    I think I need a new wave guide cover. My microwave (GE JES1288SH01) has start sparking inside. Do you know if it is the mica that I need if I have to buy the sheet? Also, I am in the US, Not sure about the prices on your site (your dollar sign is different from ours).

    • You can test the oven by heating a mug of water in the oven without the waveguide cover in place for a short time. If all behaves ok as you would expect then you will be ok changing just the waveguide cover

  29. Maríshall says:

    Hi, my mwave started to arc. I was about to chuck it and get a new one. In SA they are quite cheap and to repair it pricey…Might as well buy a new one. Then my conscious got the better of me…what if it is something small. I saw a video on YouTube implying that the waivegaurd/resistor could be faulty. I took it of, and no arc. My next actual concern: must the magnetron be replaced? The resistor was slightly burned. The one repairs company tried to imply that once the waveguide has burned, the magnetron might be faulty as well. Just want to confirm the correctness of this as I Don’t want to be conned. And then I also have the same concern as everybody else: health risks, whether short or long term.

    • The magnetron is usually very close to the waveguide cover but wont necessarily be damaged. You can test the oven by heating a mug of water in the oven without the waveguide cover in place for a short time. If all behaves ok as you would expect then you will be ok changing just the waveguide cover

  30. jason williams says:

    can you use plastic to make one…..

  31. Ekenem Uruakpa says:

    Please what’s the alternative for waveguide mica, if I cant access any now, till I buy one. I live in Africa. I hope to order, but till then, can I use cardboard for now as alternative, till I gate the real thing.

    • Cardboard is likely to soak up too much moisture (condensation). The microwaves will then be attracted to the moisture in the cardboard and will make that hot, instead of the food.

  32. nicholowen says:

    Hi, Microwave expert! My waveguide broke in half, and I repaired it with duct tape.
    There have been no sparking, noises or discolouration. Is there anything I should be worried about?
    (Thanks on behalf of microwave noobs for answering these inquiries for so long!)

  33. Md Azian Aziz says:

    Hai!! I like to buy a pice of waveguide cover for my microwave avon ..
    1. About 5inc x 6inc
    2. What is the price
    For yr info I am staying in klang selangor

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