Menu
Close
sales@gertul.com.cn 0512-63950980
CN

News

Basic knowledge and selection method of microwave and millimeter wave coaxial connectors

Date:2021-11-20 16:17

When it comes to microwave circuits, one cannot fail to mention coaxial connectors. No matter which frequency band your circuit is in, as long as it needs to be measured on spectrum analyzers, network analyzers and other instruments, you need to use coaxial connectors.

There are many types of coaxial connectors: SMA, SMB, SMC, APC-7, K connector and so on. No matter what kind of connector you are using, you need to pay attention to its applicable frequency range before using it. The frequency range of the connector is limited by the excitation of the first circular waveguide propagation mode in the coaxial structure. Reducing the diameter of the outer conductor will increase the highest frequency that can be used; filling the space with insulators will reduce the highest frequency that can be used and increase system loss. The performance of all connectors is affected by the quality of the connector interface. If the diameters of the inner and outer conductors deviate from the size required by the design, the plating quality is poor, or the gap at the connection is large, the reflection coefficient and resistive loss of the interface will be degraded. This is why the same kind of connector can be used at higher frequencies with good quality, and the standing wave coefficient is smaller. Of course, if your circuit frequency is relatively low. Original: Knowledge about microwave and millimeter wave coaxial connectors , Or it’s just a test version. When the requirements are not high, you can buy a few dozen yuan directly at the Chenghuang Temple.

The following briefly introduces several commonly used connectors in measurement and test applications.

APC-7 (7mm) connector

Among all 18GHz connectors, APC-7 (Amphenol precision connector-7 mm) has the lowest reflection coefficient and can provide the most repeatable measurement. This connector was jointly developed by HP and Amphenol in the 1960s. This is a connector with a non-polar design, which can be suitable for the most demanding applications, especially the requirements of metering and calibration applications.

N type connector

The N-type (US Navy) 50Ω connector is a connector designed for military systems below 4GHz in the 1940s. Improvements in the 1960s pushed performance to 12GHz and later to 18GHz. Some 75Ω products use an N-type design with a smaller center conductor diameter, but are not compatible with 50Ω connectors.

SMA connector

I believe this is the connector that everyone usually touches the most. As long as you are making circuits, you will basically use it. (Unless you are making millimeter wave circuits, you may not have used it. Original: Knowledge about microwave millimeter wave coaxial connectors ) The SMA (mini A) connector designed by Bendix Scintilla is one of the most commonly used RF/microwave connectors. It uses semi-rigid cables and is suitable for infrequent connections. Due to the difficulty of fixing the dielectric support, the reflection coefficient of most SMA connectors is higher than other connectors when it is used up to 24 GHz.

3.5 mm connector

The 3.5 mm connector was mainly developed by HP, now Agilent, and was manufactured by Amphenol in the early days. Its design strategy is to use a conventional SMA size to achieve a highly reliable physical interface to achieve thousands of repeated connections and reach 34GHz.

1.0 mm feedthrough

One end of the feedthrough adapter is a 1.0mm female connector, and the other end is a glass-to-metal sealed interface. It is suitable for ultra-high frequency (up to 110 GHz) signal hopping from coaxial to microstrip package or circuit board.

2.92 mm connector

This is the K connector we usually use. In 1983, William. Old. Field senior engineer of Wiltron Company developed a new type of K-type connector based on summing up and overcoming the millimeter wave connector that was previously introduced. It can be used in the DC-46GHz frequency band, has good electrical performance, and is compatible with the widely used SMA connectors, and is quickly recognized by the majority of manufacturers, and has become the most widely used millimeter in the world. One of the wave connectors. The 2.92mm connector can be adapted to SMA and 3.5 mm connectors. When used in the 46GHz frequency band, the performance is excellent, and the price is cheaper than the 3.5mm connector; when used below 18GHz, the performance is better than the SMA connector. So, don’t be surprised when you see that the K connector is similar in appearance to the SMA connector, but the price is dozens of times more expensive. It is a high-end product.

2.4 mm connector

The 2.4 mm connector is a 50 GHz connector jointly developed by HP, Amphenol, and M/A-COM. This design solves the fragility problem of SMA and 2.92 mm connectors by increasing the thickness of the outer wall and strengthening the socket. It can accurately fit with SMA, 3.5mm and 2.92 mm connectors. However, because there are not as many manufacturers of 2.4mm connectors as K-type connectors, and the price is higher, the application is not as wide as K-type connectors.

1.85 mm connector

The 1.85 mm connector is a connector developed by HP in the mid-1980s, which is now Agilent, and its operating frequency reaches 65 GHz. In 1988, HP provided this design to the public domain to promote the standardization of connector types; through research and development, several manufacturers can provide several such devices. The 1.85mm connector is compatible with the 2.4 mm connector and has the same robustness. In recent years, 1.85mm connectors have been optimized to reach 67 GHz frequency. Many experts believe that this connector is the smallest coaxial connector possible for general use up to 67GHz.

1.0 mm connector

The 1.0 mm connector is designed to support all transmissions up to 110 GHz, which is an important achievement of precision manufacturing that enables reliable and flexible interconnection.

To summarize briefly: If the circuit you need to measure and test is below 18GHz, you can choose SMA connector, N-type connector and APC-7 connector, which one to choose depends on your circuit type, cost, etc. Consider, if your boss has too much money to spend, you can also use K-type connectors and other originals: knowledge about microwave and millimeter wave coaxial connectors. If you are measuring and testing in the millimeter wave frequency band, you can choose a K-type connector or a 2.4mm connector. Why not choose 3.5mm connector? Because compared with the K-type connector, it has neither price advantage nor performance advantage (the applicable frequency is not as high as the K-type connector).

  • Connect
  • Factory Address: No. 499, Jiangxing East Road, Wujiang Economic Development Zone, Suzhou
    Del: 0512-63950980
    Fax: 0512-63950981
    Mail:sales@gertul.com.cn
    Sales address: A12, Building 1, No. 1358, Jianan Road, Minhang District, Shanghai
    Del: 0512-63950980
    Fax: 021-33275711
    Web: www.gertul.com.cn
  • Share and follow
  • Subscription Information
Copyright © Suzhou Gertul Microwave Technology Co., Ltd. . All Rights Reserved Web design