Category Archives: Radio

Coaxial SMA Connector

What is an RF connector?

An RF connector is an electrical connector that works with radio frequencies set in the multi-megahertz range. These connectors are usually used with coaxial cables and are designed to keep their shielding. Mechanically, RF connectors use a fastening mechanism to allow a low ohmic electric contact, whilst sparing the gold surface. This allows more than 1000 reconnections and a reduction of the insertion force.

What is an SMA connector?

SMA connector, or SubMiniature version A connector, is a coaxial RF connector that was developed as a minimal connector interface for coaxial cables with a screw type coupling mechanism. It has a 50 Ω impedance, and presents exceptional electrical performance from DC to 18 GHz.

SMA Connector Design

  1. An SMA connector is composed of a 0.250×36 thread.
    • The male is fitted with a .312 inch hex nut that should be properly torqued with a 5/16 inch wrench, 3-5 in for brass, and 7-10 in for stainless steel connectors.

  2. SMA connectors are rated with 500 mating cycles.
    • It uses a polytetrafluoroethylene (PTFE) dielectric that comes in contact in the mating plane.
    • The outer shell of the male or plug connector contains an inside thread and an inner pin that often causes confusion. In SMA, the male connector refers to the “plug”, whereas the female connector refers to the “socket”.

Reverse Polarity SMA

Reverse Polarity SMA, or RP-SMA and RSMA, is a commercial variation of the SMA connector specification, where it reverses the male and female interfaces. It features the same external housing as a standard SMA plug connector. However, its internal pin is replaced with a female inner pin. In order to avoid confusion with the terms “male” and “female” with reverse connectors, these terms should be replaced with the terms “plug” and “jack” respectively.

RP-SMA connectors are predominantly used by Wi-Fi equipment manufacturers in compliance with specific local regulations. The term reverse polarity may be confusing to non-Wi-Fi engineers as the reverse of polarity may be thought to refer to electromagnetic polarity instead of the reversal of the gender interfaces.

BNC Connector

What is an RF connector?

An RF connector is an electrical interface developed to work at multi-megahertz radio frequencies. They are used with coaxial cables where they are designed to maintain the cables’ shielding. Mechanically, RF connectors use a fastening system to facilitate a low ohmic electric contact, sparing the gold surface at the same time. This feature allows for more than a thousand reconnections and a reduction to the insertion force.

What is a BNC connector?

A Bayonet Neill Concelman, or BNC, connector is a universal type of RF connector mounted at the end of coaxial cables. Its fastening tool uses mated terminals consisting of a male and a female side with matching slots.

Uses of a BNC Connector

A BNC connector is used in the following applications and technologies:

  • Connections using RF signals;
  • Serial digital and Analog interface;
  • Video signals;
  • Aviation electronics;
  • Non-professional radio antenna connections; and
  • Electronic test equipment.

BNC connectors also function as a substitute to RCA connectors when used for video on commercial video devices.

BNC Specifications

There are two versions of BNC connectors. These are the 50 and 75-ohm versions. These designs were to mate with each other, although the impedance difference could lead to signal reflections.

The 50-ohm versions, which were originally the only versions available, were matched with cables of different impedances. The 75-ohm versions have reduced or missing dielectric at the mating ends. These are typically for frequencies up to 4 GHz.

Similar Connectors

  • The TNC connector, or the threaded Neill-Concelman connector, is a threaded version of a BNC connector. It has 50 Ω impedance and best operates at the 0-11 GHz frequency spectrum. It performs better than a BNC connector in microwave frequencies performs, and can be used in a variety of radio and wired applications.
  • LEMO 00 miniature connectors have replaced BNC connectors in their application with NIM electronics because the former provides for higher densities. Likewise, MHV and SHV connectors are for higher voltages.
  • Like an ordinary BNC connector, a twin BNC connector also uses a bayonet latching shell. However, the latter contains a female and male contact points, thus allowing the connection of a 78-ohm and a 95-ohm shielded differential pair. Nonetheless, regular DNC connectors cannot match with Twin BNC connectors.
  • Triaxial connectors are BNC variants that feature both a signal and guard, and a ground conductor. It also incorporates a three-lug arrangement to guard against accidental or forced mating with BNC connectors. This type of connector is used in sensitive electronic measurement systems.

For more information on BNC Connector read:

  • BNC Connector
  • BNC Connector
  • Modulation

    Modulation is a process in telecommunications where periodic waveforms are modified so they will vary from one another. A waveform characterizes the shape and form of a specific signal. When waveforms are given certain variations, a particular message is conveyed.

    Modulation can be compared to the process in which an individual would modify the sound of a musical instrument. In this case, the tone of the instrument can be considered as the waveforms.

    Modulation consists of several components and parameters. The waveform used in modulation is usually a high-frequency sinusoid. A sinusoid is a function describing a wave-like property of time. These sinusoids are used as carrier signals in modulation.

    The carrier signals in modulation have three main parameters: amplitude, phase, and frequency.

    Amplitude refers to the amount of change in the signal.

    Phase is the fraction of a full cycle which corresponds to an offset. This offset is found within a displacement from a particular reference point at a given time.

    Frequency is the measurement of the number of occurrences of an event within a period of time.

    To obtain the modulated signal, all of the three parameters are modified using a low frequency information signal as the reference point.

    The concept of modulation has inspired the development of certain devices. Modulators, for instance, perform the process of modulation while demodulators do the inverse structure of the said process. A device that can do both modulation and demodulation is called a modem, widely used for Internet purposes. Other common devices that apply the concept of modulation include AM and FM radios.

    WCDMA

    Wideband Code Division Multiple Access (WCDMA) is a radio access system used for 3G cellular networks popular over many parts of the globe. The third generation systems sustain wideband services like video, fast Internet access, and premium image transmission.

    In this system, the air interface of CMDA is integrated with GSM based networks. The standard for this system was developed by way of the Third Generation Partnership Project (3GPP), which aims to facilitate interoperability among the 3G networks. The standard that has developed by way of this collaboration venture is based on the Terrestrial Radio Access of the Universal Mobile Telecommunication System (UMTS).

    The information is transmitted over a band of approximately 5MHz. The wide bandwidth spread by this system paved way for its name, Wideband CDMA.

    Modes of Operation

    There are two different methods of operation in WCDMA:

    • Frequency Division Duplex (FDD) employs two separate frequency bands for the uplink and downlink transmissions of this duplex method. Paired frequency bands with assigned separation are given for a connection;
    • Time Division Duplex (TDD) transmits the uplink and downlink transmissions over similar frequency band through coordinated time intervals. Hence, a physical channel’s time slots are separated into reception and transmission parts.

    Since different areas have varying frequency allocation schemes, the system’s ability to work in either mode enables effective use of the available spectrum.

    Key Features of WCDMA

    The key features for this system are:

    • 5MHz wide radio channels;
    • Support of high data transmission rate: 2 Mbps for local coverage and 384 Kbps for wide area coverage;
    • Chip rate of 3.84 Mbps;
    • Ability to support two modes of operation: time division duplex and frequency division duplex. Frequency division is used with one frequency for downlink and another for uplink. For time division, 16 slots per radio frame are used by FOMA, 15 by UMTS.M;
    • High service flexibility or the ability to sustain numerous parallel changeable rate services on each connection;
    • Consistent detection on both uplink and downlink transmissions depending on the channels and pilot symbols;
    • Efficient packet access;
    • Built-in transmitter diversity, advanced receiver structures, and adaptive antennas for future capacity; and
    • Multi-code transmission.