JEM Engineering, through the American Red Cross, will be providing financial assistance to households that were severely impacted by recent Hurricanes Harvey and Irma, as well as the impending Hurricane Jose.
As part of our efforts, we are also collecting monetary donations from the community. If you are interested in donating, you may contact us for additional information.
Why donate through JEM? Make your donations go twice as far!
Every gift you make is significant in our disaster relief efforts. We want to double your gifts so that our efforts will move twice as fast! JEM will match donations you make by 100%.
Like with most products, an antenna’s outstanding performance in the field must be preceded by outstanding performance in the lab.
It is JEM Engineering’s job to not only design and manufacture antenna products, but also to qualify them to meet RF specifications, as well as environmental standards such as military standard MIL-STD-810 and RTCA/DO-160. Because of this, not only do our products survive strenuous environmental conditions; they perform well. We extend the same guarantee to our customers by offering them the same qualification services.
Our rigorous qualification procedures combine our own internal testing capabilities with those of our external testing partners. In this post, we list some of our in-house qualification capabilities.
• Efficiency Measurements
The radiation efficiency, or simply “efficiency” of an antenna is commonly defined as the ratio of the power radiated from the antenna, in relation to the power delivered to the antenna. JEM’s Spherical Near-field Chamber (SNF) and Tapered Antenna Test Facility (TATF) chambers generate efficiency plots, in addition to as addition to radiation patterns, and ASCII Data Files.
• Directivity Measurements
Directivity is one on of an antenna’s key performance factors. One can define it as the ability of an antenna to focus energy in a particular direction when transmitting. Directivity also measures the antenna’s ability to receive energy better from a particular direction.
• Gain Measurements
Another useful performance measurement is the antenna’s gain. It combines the antenna’s efficiency with its directivity. The gain measurements we provide as part of our data package include peak, average, maximum linear, minimum linear, horizontal, and vertical, as applicable. Additionally, SNF and TATF chambers generate gain measurements for antennas within two different frequency ranges. The SNF measures from 400 MHz to 6 GHz , while the TATF measures 80 MHz to 40 GHz.
• VSWR and Return Loss
Voltage standing wave ratio, or “VSWR,” is a measure that describes how well the antenna impedance -or voltage to the current at the antenna’s input- “matches” to the radio or transmission line it is connected to. A good match allows a transmitter or receiver to deliver power to an antenna without excessive reflection back on the line (return loss). At JEM, a single VSWR measurment, including system calibration, takes less than 10 minutes. In fact, minus calibration, it only takes 1 minute or less to complete a test!
• Radiation Patterns
An antenna’s radiation pattern measures the strength of its radio waves in relation to the direction at which the waves travel. We can generate both 3-Dimensional, as well as 2-Dimensional renderings of radiation patterns.
Steered Array 3-D Pot
Steered Array 2-D Plot
• Human Body Interaction
Besides producing full-spherical radiation patterns, our SNF chamber can accommodate a human test subject. This allows us to take accurate measurements of body interaction effects on body worn and handheld devices.
JEM Engineering technicians testing a wearable antenna in our SNF chamber in Laurel, MD
• Temperature Effects
Temperature testing allows us to determine how a complete product, its parts, and its sub-assemblies are affected by extreme temperatures, as well as changes in temperatures. Consequently, this also allows us to assist customers in analyzing the cost effectiveness of manufacturing a product and using its components.
Our team of experts has access to advanced simulation software, therefore, allowing us to measure in-situ performance, and eliminating need to run a physical test.
At JEM we offer a variety of communications antennas, each tailored to meet a specific need. In this article, we reintroduce some of our comms antennas.
Handheld Communications Antennas – Our high-power antennas are ground plane independent. The ruggedized, weather-resistant JEM‐9051 is just one of the handheld communication antennas we designed. Nicknamed “The Power Ducky”, it is a flexible whip antenna covering 90 – 512 MHz with 25 W CW of power handling. This antenna is designed for low‐profile and man‐portable wideband communications using high power amplifiers.
JEM-9051 | Frequency Band: 90 – 512 MHz | VSWR: 1 (typical) | Polarization: Vertical, Linear | Gain: ‐20 dBi to 0 dBi | Power: 25 Watts CW
+ High Power Handheld Antenna
+ Ground Plane Independent
+ Class Leading Gain & Pattern
QHA-081| Frequency Band: 800-1000 MHz | VSWR: <2.0:1 | Polarization: Circular, RHCP | Gain: >8dBi | Power: 25 Watts CWIn-building Communications Antennas – One of our antenna products’ common features is versatility. The QHA-081 right-hand Helix Antenna is circularly polarized, operating at frequencies 800-1000 MHz. Aside from in-building communications, this antenna is suitable for multiple wireless applications.
+ Circularly Polarized
+ Designed for in-building communications
+ Suitable for Multiple Wireless Applications
Unmanned Aerial Vehicle (UAV) Communications Antennas – Another versatile antenna is the UVW-1547, a UAV and vehicular qualified antenna is designed for ground-to-ground, ground-to-air, and air-to-ground communications systems. This antenna is optimized for the L, S, and C-band downlinks with low drag operations. The antenna is also optimal for SIGINT and sensor systems.
UVW-1547 | Frequency Band: 1500 – 4700 MHz | VSWR: < 3.0 : 1 | Polarization: Vertical, Linear | Gain: 0 dBi (Boresight) 3.3 – 9 dBi (+20°) | Power: 10 Watts CW
+ Designed for Ground‐to-Ground,Ground‐to‐Air, and Air‐to‐Ground Communications Systems
+ Suitable for SIGINT, ISR, and Sensor Systems
+ Optional magnetic mount or tubular chassis mounting assembly
Satellite (SATCOM) Communications Antennas – We have developed a number of antennas used for satellite communications, many of which can also be mounted onto a vehicle’s or an aircraft’s surface with no degradation to the pattern or VSWR. The HSA‐2438LP, also known as the “Low-Profule MUOS SATCOM Antenna” is a hybrid spiral antenna operates on 240 – 380 MHz. It can be flush mounted on a vehicle or airborne surface and its pattern is designed for uniform gain overhead to 40 degrees in elevation.
HSA-2438LP | Frequency Band: 240 – 380 MHz | VSWR: < 1.5 : 1 | Polarization: Vertical, Linear | Gain: 3 dBic, overhead | Power: 50 Watts CW
+ Flush mountable for low visibility
+ Ground Plane Independent
+ Optional Clamp Mounts for Quick Connect in All-Terrain Vehicle Operation
More about JEM Engineering
JEM Engineering’s team boasts over 150 years of combined experience, allowing them to take an antenna concept all the way through to full-scale production. All JEM’s antennas are qualified and tested in-house at their facility in Laurel, MD.