APELC PWTS Portable Wideband Test Source

The APELC Portable Wideband Test Source (PWTS) is a high-power wideband antenna system typically used for MIL-STD 464 testing, IEMI susceptibility, and threat-survivability demonstrations for electronic equipment. Wideband antennas available with this system include center frequencies of 60 MHz, 100 MHz, 250 MHz, and 400 MHz. Each antenna can be used in vertical or horizontal polarity. The system is stored in a weather-tight insulated refrigerated trailer and deployed and erected when needed for testing.

Control Rack

Tektronix TDS 2002B Digital Oscilloscope E-Stop Panel Marx Air Flow Control Panel Dipole Air Flow Control Panel APELC High Rep-Rate (HRR) Trigger Unit with selectable input Lambda 802L HVPS BNC Model 575 Pulse Delay Generator

Waveforms

(a) An overlay of 21 waveforms acquired during testing.
(b) The corresponding spectral density.

Control Room

MWTS

The Portable Wideband Test Source is comprised of several different subsystems:

• The PWTS radiator 
• The Marx generator 
• The cart and mast assembly 
• The control rack

The entire system is integrated into a 48-foot refrigerated trailer comprised of a work bay and a control room. The work bay houses the PWTS radiator, the Marx generator, and the cart and mast assembly when the system is not in use. The control room houses the control rack and other ancillary systems required to safely operate the PWTS.

The PWTS radiator is comprised of a proprietary dipole antenna design that features an integrated LC resonator driving the dipole arms. The capacitance of the resonator is impulse-charged to high voltage using a Marx generator. When the resonator capacitance reaches the desired charge voltage, a spark gap (collocated with the integrated resonator) fires creating the resonance that drives the dipole arms. The dipole arm lengths are designed to be efficiently driven by the integrated resonator. The dipole antennas used in the PWTS are backed by corner reflectors to increase gain/directivity and reduce side lobes. The system is delivered with a 60-MHz dipole and collapsible corner reflector (other available antennas include the 100, 250, and 400 MHz dipoles). The Marx generator is mounted to the corner reflector frame to maintain the minimum possible Marx output cable length resulting in maximum charge delivered to the dipole resonator.

The 60-MHz dipole antenna is fastened to the corner reflector using fiberglass standoff rods. The entire dipole/reflector/Marx assembly is mounted to a cart that travels vertically along the system’s mast. The aforementioned arrangement provides the desired vertical system versatility allowing adjustment of the centerline height of up to 15-feet above the ground. The system mast facilitates not only the vertical adjustment, but also allows for minor steering of the antenna while deployed. Additionally, the mast collapses to a horizontal position resting in a cradle on a horizontal cart that enables storing the antenna inside the trailer.