Model 8357-800 - Four-Helix Array Antenna
This antenna operates in the INMARSAT satellite communications frequency band of 1525 - 1660.5 MHz. It is configured as a set of four 24 inch long helices mounted to an aluminum frame and connected together with a Wilkinson 4-way power combiner. It interfaces with any standard camera tripod for positioning. Handling up to 70 watts of RF power, this antenna can be used as part of a portable satellite communications link. The helical elements stow in a carrying case for transportation.

Model 8613 Series - L-Band Helix Antennas

These are simple helices for use in fixed-site L-band satalilite applications. All have an axial ratio less than 2 dB, can handle up to 70 watts CW with a frequency range of 1525 - 1660.5 MHz. The sealed construction uses a polycarbonate radome. An SMA jack connector is standard; an N jack is an option. Diameter is 2.38 inches. These antennas are available on special order with left-hand polarization sense.

Model 9610-800 - VHF Helix Antenna

100 - 160 MHz. 6.0 - 12.8 dBic gain. This very large 8-turn helix has right-hand circular polarization with an axial ratio less than 2 dB. It is15-feet long with a 28 inch pitch diameter. The circular cup reflectors are 6-feet in diameter. The assembly weighs 150 pounds.
Model 9610-810 is identical but has left-hand sense.

Model 8617-810 - High Gain UHF High Power Helical Antenna

For uplinks to UHF satellites, this antenna operates from 236 - 330 MHz with right-hand circular polarization with a gain of 12 to 17 dBic. Overall length is 10 feet. A special perforated metal cup reflector increases gain and reduces sidelobes. The antenna comes complete with an elevation/azimuth pipe mount allowing for elevation adjustments from horizon to 65°. Equipped with a type N connector, this antenna can handle up to 1 KW of RF power.

Model 8617-800 - High Gain UHF Helical Antenna

This antenna is similar to the Model 8617-800 except that it covers the 310 - 400 MHz frequency band and has an overall length of 7 feet.

Model 9339-800 - DARS Helical Antenna

This helix operates in the DARS frequency range of 2.31 - 2.36 GHz, has 6.5 dBic gain with a 72° beamwidth.

Model 9392-800
Antenna Omni

Remote Monitoring Station (RMS)

Helical Array Antennas
Models 9370-820 and 9507-800

These innovative antennas were designed to receive L-band signals from the AMSC (101°W) and TMI (106°W) satellites. Model 9507-800 is used for the Solidaridad (109.2°W and 113.0°W) satellites.

The radiation pattern of the two helical elements in the hour angle plane (array plane) is determined by the element spacing and by the helix element pattern. For hour angles greater than 35°, the helix elements provide good discrimination against other L-band satellites.

Each element is fed into a hybrid. One hybrid port forms an on- axis beam, the other has an on-axis null whose off-axis peaks are arranged to be at the angle of the adjacent satellite(s). Therefore, the sum port receives the AMSC 101° satellite and the difference port receives the adjacent satellite.

Careful balancing of the array element signals results in isolation of at least 20 dB between the two signals. The antenna is mounted to a standard polar mount which automatically aligns the array plane to the Clark orbit plane. For TMI, each helix is 22 inches long and the element baseline is 40 inches. For Solidaridad, each helix is 27 inches long and the baseline is 50 inches.

This antenna effectively replaces two 3.7-meter parabolic reflectors which have equivalent angular discrimination. The result is an RMS antenna system cost savings of 90%.

Model 9392-800 - Helicopter-borne Helical Antenna

Mounted inside an aerodynamic radome, this antenna operates in the 1.2 - 1.35 GHz frequency range. It is left-hand polarized with a beamwidth of 60°, a gain of 11 dBic and can handle 100 watts CW.

Model 9171-810 - Helical Array

This six-element helix array is fed from a microstrip power divider. A radome covers each element. Operating in the 3.65 - 6.425 GHz C-band SATCOM frequency range, this antenna is used in mobile satellite systems aboard moving vehicles. It has a gain of 15 dBic with beamwidths of 12° azimuth and 70° elevation.

Model 9171-810
C-band Array

Model 9370-820
RMS Monitoring Station Antenna

Helix Feeds
Helices can be used as feeds for parabolic reflectors.

The following are some typical designs. For INMARSAT helix feeds, please see Page 103.

Model 8881-800 - Frequency 1.20 - 1.66 GHz. Receives the GPS L1 and L2 signals and operates in the standard L-band SATCOM range with right-hand sense.

Model 8231-890 - Frequency 1.365 - 1.375 GHz. Handles 400 watts PEP. Connector is an N jack. 3 inch diameter, 4 inches long, 4 inch square ground plane.

Model 9826-800 - Frequency 1.525 - 1.660 GHz. Retrofits standard Ku-band DSS antennas for L-band SATCOM.

Model 9203-810 - Frequency 4.0 - 5.5 GHz. Used with a 4-foot reflector in a telemetry application. 3 inches long, 3 inch diameter.

Model 8231-890
L-band Feed

Model 9203-810
C-band Feed