{"id":3848,"date":"2026-07-08T07:40:31","date_gmt":"2026-07-08T07:40:31","guid":{"rendered":"https:\/\/theemcnews.co.uk\/?page_id=3848"},"modified":"2026-07-08T07:47:11","modified_gmt":"2026-07-08T07:47:11","slug":"view-inside-a-mode-stirred-chamber-the-rotatable-tuner-to-the-top-has-a-diameter-of-approx-5-m","status":"publish","type":"page","link":"https:\/\/theemcnews.co.uk\/index.php\/view-inside-a-mode-stirred-chamber-the-rotatable-tuner-to-the-top-has-a-diameter-of-approx-5-m\/","title":{"rendered":"View inside a mode-stirred chamber. The rotatable tuner to the top has a diameter of approx. 5 m."},"content":{"rendered":"\t\t
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Achievable Field Strength in Reverberation Chambers<\/p>

Authors: N. Eulig, A. Enders, H. G. Krauth\u00e4user, J. Nitsch<\/p>

Affiliations: 1. Technische Universit\u00e4t Braunschweig, Institute for EMC, Germany 2. Universit\u00e4t Magdeburg, Institute of Electrical Engineering and Electromagnetic Compatibility, Germany<\/p>

Abstract: Mode-Stirred Chambers (MSCs), also known as reverberation chambers, are widely used for electromagnetic compatibility (EMC) immunity testing. One of their major advantages is the ability to generate high electromagnetic field strengths while requiring significantly less RF power than conventional anechoic chambers. For safety-critical electronic systems, such as automotive and avionics equipment, field strengths exceeding 100 V\/m are often required. While reverberation chambers can achieve these levels efficiently because of resonance effects, the achievable field strength decreases as the chamber volume increases. Large chambers are needed to support low-frequency testing, creating a trade-off between low operating frequency and high achievable field strength. This paper compares different reverberation chambers and determines the frequency range where using an MSC is most advantageous.<\/p>

  1. Mode of Operation<\/li><\/ol>

    A reverberation chamber consists of a shielded metallic room and a rotating metallic tuner (stirrer). The tuner continuously changes the electromagnetic field distribution inside the chamber while the excitation frequency remains constant. This ensures that the resonant field maxima move throughout the chamber and the Equipment Under Test (EUT) experiences nearly uniform exposure. Field variation across the test volume is typically within 2\u20134 dB during one complete tuner rotation. The chamber operates effectively only above its Lowest Usable Frequency (LUF), which depends on chamber dimensions, geometry, and stirrer design. Each chamber therefore has its own unique LUF.<\/p>

    1. Loss Mechanisms, Quality Factor (Q), and Chamber Gain (G)<\/li><\/ol>

      The primary loss mechanism in an empty reverberation chamber is power dissipation in the metallic walls. At higher frequencies, antenna losses become negligible while wall losses dominate. The quality factor (Q) depends on chamber volume, surface area, wall conductivity, and frequency. As frequency increases, wall losses increase and Q changes accordingly. When an Equipment Under Test (EUT) is placed inside the chamber, additional absorption occurs, reducing Q and field strength unless additional RF power is supplied.<\/p>

      1. Electrical Field Strength Distribution<\/li><\/ol>

        The electric field strength depends on frequency because chamber losses vary with frequency. Typically, field strength initially increases with frequency and then decreases due to increased wall absorption. The presented analysis compares different chambers at a fixed frequency of 1 GHz for consistency.<\/p>

        1. Electrical Field Strength vs. Chamber Surface Area<\/li><\/ol>

          The relationship between electric field strength and chamber surface area is E \u221d 1\/\u221aS, where E is the electric field strength and S is the chamber surface area. This means larger chambers produce lower field strengths for the same input power. Wall material conductivity should remain similar when comparing chambers. Experimental measurements confirm this inverse square-root relationship.<\/p>

          1. Error Sources<\/li><\/ol>

            Several factors may affect measurement accuracy, including different wall conductivities, differences between net power and input power, statistical variation in measured electric fields, and the number of tuner positions used during measurements. These factors can introduce variations of several dB.<\/p>

            1. Discussion<\/li><\/ol>

              Designing a reverberation chamber involves balancing two competing goals: achieving a low Lowest Usable Frequency (LUF), which requires a large chamber, and achieving a high field strength, which favors a smaller chamber. Consequently, large chambers support lower-frequency testing, while small chambers provide stronger electromagnetic fields with less RF power. For low-frequency EMC testing, conventional anechoic chambers may be more practical because reverberation chamber measurements near the LUF require considerably more measurement time.<\/p>

              \u00a0<\/p>

              Key Takeaways: Reverberation chambers generate high field strengths efficiently. Increasing chamber size reduces achievable field strength. Lower operating frequencies require larger chambers. Chamber designers must balance field strength and frequency range. Above a certain frequency, reverberation chambers become an effective alternative to anechoic chambers.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"

              Achievable Field Strength in Reverberation Chambers Authors: N. Eulig, A. Enders, H. G. Krauth\u00e4user, J. Nitsch Affiliations: 1. Technische Universit\u00e4t Braunschweig, Institute for EMC, Germany 2. Universit\u00e4t Magdeburg, Institute of Electrical Engineering and Electromagnetic Compatibility, Germany Abstract: Mode-Stirred Chambers (MSCs), also known as reverberation chambers, are widely used for electromagnetic… <\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"elementor_header_footer","meta":{"footnotes":""},"class_list":["post-3848","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/3848","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/comments?post=3848"}],"version-history":[{"count":7,"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/3848\/revisions"}],"predecessor-version":[{"id":3859,"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/3848\/revisions\/3859"}],"wp:attachment":[{"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/media?parent=3848"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}