Wound magnetic devices are designed to transfer of energy over a wide frequency range. Usually broadband transformers are wound on ferrite rods and threads. This is used in the equipment of Telecomm. Binocular cores and Balun are used for broadband transformers and it must accommodate RF power.
Conventional and transmission-line types are the two kinds of transformers:
The former type allows transformation ratio that we usually need
The latter comes with parallel or twisted wingdings that helps to produce a specific interface of transformations like 16:1 and 4:1 and 9:1.
For determining the Minimum- Number – of – Turns impedance ratio square root is used. The primary resistance is around 5 times the impedance. A resistance of 1000 ohms is allowed with a 200 ohm to 50 ohm transformer and it needs inductance of 88 uh.
Ferrites are used for Balun cores. The core material permeability is usually around 850 to 900. It is designed by placing two thirds of far-right side by side. Quick setting epoxy is used to glue cores together to create separate toroid tubes of two.
Usually frequency based broadband transformers have medium or low level of frequency. Fair-Rite 78 or 77 materials are examples of manganese zinc ferrites and they are very ideal. In order to reduce the Rdc ratio core geometry be used. For a high level of frequency Nicke zinc ferrites are used as the core materials. The band pass lies above 500 kHz.
For active mixer broadband transformers are used as output. For matching an antenna of 50 ohms to a grounded gate an amplifier is used to receive and convert. Two broadband transformers are used in push-pull RF power amplifier.
Transformers can also be created for providing DC isolation. Matching of impedance and specific voltage and current ratios. It provides coverage of 1.8 to 30 MHz and have an efficiency of 90% range.