Low DK thermoplastic substrate for broadband antennas

A. Helminen, T. Kiikka, Jussi Säily, Ismo Huhtinen, Jouko Aurinsalo

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    1 Citation (Scopus)


    In high frequency circuit boards PTFE is widely used as a substrate material. It offers very low dielectric constant and low losses. However, it is relatively expensive to fabricate, making the cost of PTFE laminates high. In addition PTFE-based circuit boards are composite materials with glass fiber reinforcement and thus not isotropic. Glass fiber also increases losses compared to raw PTFE. We have developed a new proprietary thermoplastic substrate especially for high frequency circuit boards. This polyphenylene ether (PPE) based substrate offers a low dielectric constant (dk), 2.55, and low dielectric loss (df), 0.002, in 1 to 5.5 GHz frequency range. It is unfilled, which makes the properties both isotropic and completely homogeneous throughout the substrate. This new material can be processed by typical thermoplastics processing methods, such as film and sheet extrusion and injection molding. Among thermoplastics, PPE is inherently low burning material and it can be easily made flame retardant (V0). However, the addition of flame retardant was found to slightly increase the dielectric loss at high frequencies. This plastic material exhibits a high glass transition temperature, Tg, around 200°C. This also gives the highest short term use temperature. There is no crosslinked structure to support the substrate above Tg. Processes requiring higher temperatures, such as conventional lead free reflow soldering or wave soldering can not be used. Because of the very good dielectric properties the material is intended for high frequency applications where the number of required solder connections is limited. One of these is a broadband base station antenna. The performance of this new material as a UMTS/WCDMA antenna for 1.92 - 2.17 GHz frequency band was evaluated with very promising results. First, a patch antenna was designed based on simulations and then the demo antenna was built. The measured performance coincided well with the simulation data. Design of a full size base station array antenna demonstrator is also presented
    Original languageEnglish
    Title of host publicationProceedings
    Subtitle of host publicationIPC APEX EXPO Technical Conference 2011
    PublisherCurran Associates Inc.
    ISBN (Print)978-1-6178-2845-4
    Publication statusPublished - 2011
    MoE publication typeA4 Article in a conference publication
    EventIPC APEX EXPO Technical Conference 2011 - Las Vegas, Nevada, United States
    Duration: 12 Apr 201114 Apr 2011


    ConferenceIPC APEX EXPO Technical Conference 2011
    Country/TerritoryUnited States
    CityLas Vegas, Nevada


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