Satellite Communications Facility

The Satellite Communications Facility (SCF) at the Johns Hopkins University Applied Physics Laboratory (APL) traces its genesis to the early days of Sputnik. Since the first signal from space, APL has provided the nation with global timing and positioning solutions, world class space and planetary science, robust and reliable spacecraft, and precise navigation, commanding and communications to ensure mission success.

Station Details
Location 39:10 N, 76:53 W
Antennas 60-foot (18.3-meter)

Quality and Cost-effective Support

Established in 1961 to support the command and telemetry requirements of the world's first satellite navigation system under contract to the U.S. Navy, the APL station has provided more than 50 years of ground contact support to our sponsors. The station has conducted over 100,000 satellite contacts in the last 15 years alone. With available, on-call technical support, the station has been conducting attended and unattended spacecraft tracking operations since 1995.

With a 50-year legacy of crafting high-quality, reliable space solutions, APL can craft a solution for your ground station requirements.

Assets at APL include two independent operational antenna systems. Our mid-latitude station can be configured to support a wide variety of missions ranging from Low Earth Orbit (LEO) through Deep Space, with a variety of data formats, including TDM and CCSDS. Current capabilities include support for L-band, S-band, and X-band communications. Quick and efficient use of antenna assets, with a 3-minute station setup and a 1-minute station tear down between contacts.

Recent system improvements and technology enhancements enable these systems to provide future sponsors with advanced capability at cost-effective rates. APL's concept of a Shared Service, Multi-mission Ground System makes the remote scheduling and data transfer capabilities of these systems highly attractive for government, academia, and commercial operations on a non-exclusive basis. While currently these systems are conducting routine daily contacts, their availability for additional contacts is still over 60%. Portions of these facilities are owned by the U.S. government and some restrictions on their use may apply.

Bill Dove
Station Manager
240-228-3766 Washington, DC
443-778-3766 Baltimore, MD

Tony Garcia
Station Systems Engineer
240-228-9535 Washington, DC
443-778-9535 Baltimore, MD

60-Foot (18.3-Meter) System

60-Meter System
Downlink S-band X-band
Frequency Range 2200-2400 MHz 8400-8500 MHz
Polarization Simultaneous RHC and LHC Simultaneous RHC and LHC
G/T >28.3 dB/K >38.5 dB/K
Beamwidth 0.5 deg 0.13 deg
Uplink S-band
Frequency Range 2025-2120 MHz
Polarization "On-the-fly" Selectable LHC or RHC
Beamwidth 0.5 deg
EIRP >80 dBW
Transmitter 2000 W Klystron (dual redundant)
Antenna Pointing Control
Program track (TLE, Spice-SPK, Chebychev, RA/DEC), S-band Autotrack, S/X-band Steptrack
CCSDS Compliant
Command, Ranging, Doppler & Telemetry, including Turbo (r1/2, 1/3, 1/4, 1/6), Convolutional (r1/2), Reed-Solomon, and Conv/R-S; Wide variety of modulation formats; Space Link Extension "SLE" (Fwd CLTU, RAF, & RCF services)

5-Meter System

5-Meter System
Downlink L-band S-band X-band
Frequency Range 1650-1750 MHz 2200-2300 MHz 8000-8500 MHz
Polarization RHC RHC RHC
G/T >11.2 dB/K >13.6 dB/K >24.1 dB/K
Beamwidth 2.5 deg 1.8 deg 0.5 deg
Antenna Pointing Control
Program track (TLE, Spice-SPK, Chebychev Polynomials. RA/DEC)


Sources: TWT-1-009 8 April, 1963 E. F. Snyder
Johns Hopkins APL Technical Digest, Jan. - Mar. 1998, V19#1
Photo Archives of the Satellite Communications Facility

The Construction of the 60 Foot Antenna at APL, nearly Fifty Years Ago.


As a result of the success of the early work done for the Navy on the concept of satellite based navigation, the Transit Program was about to become a reality. Two ground stations would need to be constructed to support the continuing work as the program headed toward an operational system.

By the 15th of November, 1962 Work on the APL Station had already begun. The first foundation, a donut shape had been determined to be inadequate and subsequently destroyed. A second foundation, approved by APL engineers was now entering the first phases of construction.

This second foundation is a rooted structure with 20 poured, steel reinforced concrete pylons 35 feet deep. Eight of the 20 pylons are drilled holes 48 inches in diameter, loaded with a welded steel reinforcement cages followed by poured concrete. The remaining 12 pylons are 14 inch diameter driven piles filled with poured concrete.

A total of more than 500 cubic yards of concrete are contained in the foundation with an estimated weight in excess of 2 Million pounds.

November 15, 1962

Drilling Hole #1 of the foundation
(notice Building 36 and several pylons in the background

Drilling Hole #8 of the foundation
(Also visible in the background, the helix antennas on Bld. 36)

Lifting a 35 foot long 3 ft. diameter Reinforcment cage into the hole.