RF CONNECTOR ANTENNAS
RF coaxial cable connectors transmit analog signals while minimizing RF (radio frequency) signal losses. These devices are designed to work at the multi-megahertz range of radio frequency. An RF connector is commonly used with a coaxial cable due to the shielding that the coaxial cable provides. A coaxial cable connector has an inner conductor that is enveloped by a concentric conducting sleeve, with the conductor and shield separated by an insulating material.
RF CONNECTOR ANTENNAS
Our RF coaxial cable connectors are engineered and are available in small sizes, with tight tolerance electrical characteristics, and in materials that are rugged but not heavy and manufactured to withstand high use in harsh environments. These connectors are manufactured with crimp, solder, and clamp terminations to enable easy installation.
Our portfolio of RF coax connectors includes MIL-standard connectors qualified for M39012, M55339, M83517. These connectors are used in television receivers, communications, Wi-Fi devices, avionics, launch vehicles, radar arrays, satellite communications, and industrial or scientific measurement instruments that use RF.
The selection of RF connector represents an important design choice for antennas and other RF systems and components, with many tradeoffs between RF connector size, weight, ruggedness, electrical performance, and mechanical features.
With so many options available it can be difficult to know which RF connector is the best choice for your antenna application. This whitepaper offers an introductory guide to many of the common RF connector types used in the antenna industry along with their pros and cons, and why using high-quality RF connectors is paramount to antenna performance and ultimately the performance of the entire RF system. This white paper will also touch on some special RF connector designs specified by Southwest Antennas for specific application needs.
The RF connector is also the most common failure point in a deployed antenna. While some antenna designs will incorporate additional mounting support structures such as a flange base that can provide additional stability, most deployed omni-directional antennas still rely on the RF connector as their only mechanical connection point.
Overlooking the importance of this during the design phase by choosing an inexpensive or poorly designed RF connector can reduce the overall electrical performance of the final antenna design in unexpected ways, and can render the antenna susceptible to mechanical failure. These failures can not only result in a loss of communication, data, or video at an inopportune time, but can be life-threatening for first responders or military personnel who depend on robust wireless communication networks for their safety and mission success.
Southwest Antennas has invested considerable engineering resources into working with select RF connector vendors in order to specify custom RF connectors that meet our unique requirements for electrical and mechanical performance. We have found many of these considerations may be overlooked when buying low-cost and poor quality RF connectors.
When using a soldered connection between the RF connector and RF cable, the materials to be soldered together must be compatible metals and of good quality. Southwest Antennas has specified a stainless steel solder shank for our RF connectors in order to ensure a rugged and reliable solder joint. The lower right photo in Figure 1 shows solder shank during the soldering process.
For military and law enforcement applications where non-reflective, low-visibility product finishes are preferred, Southwest Antennas has worked with its primary RF connector vendors to specify a unique black chrome plating process for the exterior surfaces of the RF connector.
By plating the black chrome finish it becomes part of the RF connector itself and will not chip or wear off easily. Southwest Antennas has specified a low-toxicity process to eliminate chromium and cadmium used in our black chrome plating process, resulting in a safer and more environmentally friendly product.
Within the markets for rugged antennas that Southwest Antennas serves, the most commonly deployed RF connectors are SMA, TNC, and Type-N and their variants such as rotating, non-rotating, reverse polarity, and male and female gender options.
These RF connectors are chosen by end users for a wide variety of reasons, but these commonly available RF connectors are inexpensive, can easily handle commonly used operating frequencies and RF power levels, and have high mating cycles:
For our line of concealment and embedded antennas, very small RF connectors are a necessity. These antennas are designed to be integrated into RF systems, vehicles, UAVs, environmental enclosures, concealments, or other small spaces without being visible or easily detected.
For these applications where an antenna needs to be installed in a tight space, Southwest Antennas relies on micro RF connectors such as U.FL, IPEX, MMCX, and SMP connectors. These RF connectors feature a snap fit connector instead of threads to secure the RF connectors together.
These types of RF connectors have a locking snap ring or detent internally that keeps them mated. These RF connectors can swivel or rotate freely when mated allowing for flexible RF cable routing options.
The tradeoff of this miniature size is reduced durability. These RF connectors cannot survive nearly as many mating cycles as their full-sized counterparts, generally 30 to 100 cycles (part specific). These RF connectors are not waterproof and must be used within a housing that provides protection from outdoor elements.
To provide an extra level of security in high vibration applications, Southwest Antennas has specified a line of RF connectors where fasteners have holes drilled in them and lock wires are used to keep screws from loosening and falling out over time. Commonly used on vehicles, aircraft, and trains, lock wire is secured through special hex screw heads then twisted and secured. The twisting in the wire serves as a visual indicator that the screws are installed properly, and will help keep the screws from backing themselves out when exposed to high vibrations, such as when an antenna is installed on a helicopter.
Not all antennas feature an RF connector that is attached directly to the antenna radome. For some applications, an RF cable assembly is utilized when the antenna must be located away from the radio mounting point. If male gender, the RF connector on the end of the RF cable will rotate, allowing the connector to be tightened without twisting the attached RF cable.
For body worn patch antenna applications where the product must survive immersion in water to 65 feet (20 meters), Southwest Antennas designed a unique waterproof black chrome SMA(f) RF connector with custom flange design to fit the thin form factor of the antenna. The SMA(f) RF connector flange design eliminated exposed screw fasteners by using two press fit posts that install through two holes in the radome, with epoxy used to secure and waterproof the RF connector to the radome.
In some applications, primarily related to video transmission, 75 Ohm RF connectors and cable will be used instead of 50 Ohm. 75 Ohms is a good choice for video transmission applications which tend to require less power but often rely on longer cable runs, where less attenuation is a benefit for transmission distance.
Non-rotating RF connectors are often used on omni-directional antennas as it makes the product easy to secure without tools and the connection can be made weatherproof or waterproof depending on antenna design once the two RF connectors are securely mated.
As the name suggests, non-rotating connectors have a fixed outer shell which does not rotate. To secure an antenna with a non-rotating RF connector, the entire antenna must be turned as the male and female RF connectors are tightened together. Since an omni-directional antenna radiates RF energy equally 360 degrees around the antenna, the final stopping position of the antenna as the RF connector is tightened down does not matter.
Non-rotating female RF connectors are also commonly found on directional panel and sector antennas, where the connecting RF cable will have a rotating male RF connector. All female RF connectors are non-rotating.
Rotating RF connectors feature an outside shell that can rotate independently from the rest of the RF connector assembly. The shell has threading inside, which tightens the antenna down to the mated RF connector when turned. Rotating RF connectors are useful on RF cables or coaxial goosenecks where it isn't feasible to rotate the whole product to secure one RF connector to another. Since the shell can rotate freely, it is harder to ensure that rotating RF connectors are completely waterproof once connected, unless specialized connectors are used, or additional waterproofing steps are taken. Rotating RF connectors are generally only available in the male gender configuration.
In certain cases a torque wrench is required to properly secure a rotating RF connector, especially for high-frequency applications from 18 to 24 GHz and higher. In these applications over or under-tightening can result in antenna / system performance degradation. Use of a torque wrench ensures a proper installation and tight fit without damage to the RF connector.
Right angle RF connectors and RF adapters are useful for applications where antenna or RF cable needs to be set perpendicular from the mated RF connector. These are most commonly available in both 45 degree and 90 degree angle options. These should be avoided wherever possible, but if necessary high-performance versions of these adapters should be used in order to minimize insertion loss which can be introduced by inexpensive and poorly designed right angle adapters, lowering system efficiency and RF link margin.
RF connectors that can bend up to 90 degrees are available on a limited number of antennas on the market. These are most commonly seen on commercial products such as Wi-Fi routers, where any signal degradation and mechanical weakness would not hinder overall antenna performance, and the antenna must be positioned vertically from a horizontally mounted RF connector. Cellular band antennas for commercial applications are another common use for articulating RF connectors. 041b061a72