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Resonators and Antennas Based on Substrate-Integrated Cavity Technologies

Key Takeaways

  • It is easy to interconnect substrate-integrated cavity components with active components in a PCB. 

  • Substrate-integrated cavities are fabricated on a dielectric substrate material with metal vias placed on the top ground plane, forming cavities.

  • The quality factor of substrate-integrated waveguide cavity resonators is high, making them a perfect fit for low-phase noise oscillator designs and high-gain, small-size antennas.

RF circuit using substrate-integrated cavity-based components

Substrate-integrated cavity technology is popular in RF and microwave circuits

Substrate-integrated cavity technology is popular in RF and microwave circuits, as this technology performs better than conventional components in a compact package. It is easy to interconnect substrate-integrated cavity components with active components in a PCB, and this technology provides flexibility when designing RF and microwave circuits. 

Let’s take a closer look at the advantages and characteristics of substrate-integrated cavity technologies. 

Components Using Substrate-Integrated Cavity Technologies

Substrate-integrated cavities are fabricated on a dielectric substrate material with metal vias placed on the top ground plane, forming cavities. The quality factor of substrate-integrated waveguide cavities is varied by adjusting the diameter of the vias as well as the spacing between them. 

Substrate-integrated cavities can be used to build microwave and RF devices that utilize conventional cavity technology. For example, a resonator is the main component in RF and microwave engineering utilizing cavity technology. Resonators based on substrate-integrated technologies are simple and less costly to build while still providing a solid performance. Additionally, resonators using substrate-integrated technologies are lighter. The possibility of shrinking the dimensions of substrate-integrated cavity devices by increasing dielectric permittivity leads to more lightweight resonators. 

Substrate-Integrated Waveguide Cavity Resonators

Resonators are a constant presence in several microwave applications such as filters, oscillators, etc. Compared to planar PCB resonators, substrate-integrated waveguide cavity resonators perform well and have high integration capability. The quality factor of substrate-integrated waveguide cavity resonators is high, making them a perfect fit for low-phase noise oscillator designs and high-gain, small-size antennas. Substrate-integrated cavity resonators are often used in unmanned drone aircraft, lightweight communication satellites, spacecraft, and high-frequency sensors. 

Substrate-Integrated Waveguide Cavity-Backed Antennas

Metalized via arrays through a dielectric substrate realize the design of backed antennas. Typically, substrate-integrated cavity-backed antennas are implemented in the dielectric substrate with patches and slot elements, called substrate integrated cavity-backed patch antennas and slot antennas, respectively. 

The selection of dielectric materials is important in substrate-integrated waveguide cavity-backed antennas. The dielectric constant of the dielectric substrate material influences the size of the antenna, whereas the bandwidth of the antenna is dependent on the thickness of the substrate. The optimization of the patch or slot and cavity dimensions can also increase the performance of substrate-integrated cavity-backed antennas.

Because of these advantageous characteristics—compact, lightweight, and low-cost—substrate-integrated cavity technologies are popular for use in microwave and RF circuit designs. Luckily, Cadence’s software can help when designing RF circuits with substrate-integrated cavity-based components.  

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