Balun transformers are used to convert unbalanced signals into balanced signals, and are widely used in the field of microwave technology and antennas. 
The balun transformer has a wide operating frequency and is suitable for high-power use. The transformer balun was studied, and the working principle of the transformer balun was analyzed in detail by equivalent transformation, and then the actual production and measurement methods were discussed. The balancing signal of the opposite phase of the balun transformer is converted to a single-ended unbalanced signal and sent to the unbalanced load; Conversely, an unbalanced signal can be converted into a balanced signal. In addition, it can also provide impedance conversion function, also known as a balun transformer. The balun transformer can be wound around the same magnetic ring as the original transmission line. This is the common three-wire winding method, which makes the balun widely used in the field of microwave technology and antennas.
Common baluns in balun transformers are available in high-frequency open-circuit, elimination and transformer types. The medium and high frequency open circuit balun has a narrow working bandwidth, the elimination balun has a wide frequency band, and is limited by the magnetic ring magnetic saturation when using high power, and the device balun mainly realizes the balance-balance conversion through the high-frequency transformer, which converts the unidirectional unbalanced current into a two-way flat just like the original push-pull output transformer. In order to facilitate the analysis, we transform it equivalently, according to the static circuit equivalence analysis, if the voltage at the terminal a is +, V -/voltage, and the other output terminal c is equivalent to a voltage of l 2, and the current (or vice versa) of the balance current (or vice versa) has a wide operating frequency band, which is suitable for high-power use], and. This article mainly discusses the transformer balun, which is divided and analyzed by equivalent transformation.
The balun transformer belongs to the field of radio frequency devices, and the present invention comprises two primary coils and a secondary coil. The two primary coils are formed by the disconnection of an inductor with a center tap near the center tap, and the secondary coil is a planar spiral inductor with a center tap. The primary and secondary coils are nested with each other to increase the coupling coefficient. The center taps of the primary and secondary coils are connected together and eventually connected to the ground plane. The Balun transformer can solve the problems of narrow operating frequency band, poor phase balance, large insertion loss and return loss of the existing Balun transformer when operating at low frequency.
Balun transformers cannot be used for equipment and systems that have special technical requirements or are highly dependent, traffic signaling equipment, disaster prevention equipment, medical equipment, information and communication equipment with high public use, etc. Balun transformers may be small, but if you put together a sufficient number of connectors, as in a base station, you will find that these connectors, along with their accompanying cable accessories, will form a network and be widely accepted. So, if you can reduce the size of the connector while improving performance, simplifying installation, and reducing the potential for human error, there are good reasons to replace it. These factors, along with the reduction of PIM, are likely to lead to the almost or even substantial replacement of familiar connector types such as type N and 7/16 DIN in microcells and small cells with new, smaller connectors, and this process has already begun.
Most of the components of the balun transformer can be used in the backplane as the connector size decreases, which is important for applications where space is limited. But even though these connectors may be small enough, they are clearly not enough for wireless carriers that require more space in crowded device bunkers. In addition, applications that require high data rates, such as high-definition video, require large bandwidths, which connectors must accommodate. Balun transformers can be more than 100 combined. It is not feasible to completely replace the connectors in existing analog DAS systems that transmit only RF signals over coaxial cable, but thankfully this field is growing rapidly, so new first installations may be equipped with the latest connectors at the right price.
