Various major components of the Wavebounce time domain radar are available separately.

Wavebounce.com has recently developed a new, smaller, TEM horn antenna which can be used in custom applications.  The aperture of this antenna has a new proprietary damping mechanism which greatly reduces reflections without increasing its size. This antenna operates down to approx.  200MHz and has linear gain to above 2GHz.  This antenna has approximately 1/3 the volume of previous designs (e.g., the Calspan WB1A design). 

Monocycle pulse generators are available, such as those from Avtech in Canada.  I've used them but they simply aren't clean enough for use as a high resoluton GPR pulser.  The Avtech 1nS pulser has positive and negative lobes that are not well balanced and has quite an overshoot at the end that really kills resolution.  So, I built my own well-balanced monocycle pulser with time side lobes that are at least 30 dB below the main peak.  A small internal heater/controller makes this unit very stable over time. Wavebounce can provide monocycle pulsers over a wide range of pulse widths.

Sampling heads are, as far as I know, a different matter.  I can not find a single source of an OEM sampling head anywhere in the world (please let me know if you find one besides Wavebounce). Very nice sampling systems are available on laboratory scopes but how would you imbed a microwave sampler into a piece of equipment such as a portable radar?  The latest Wavebounce unit  SM4, is very stable and reliable.  I can provide drive electronics for this sampler suitable for a wide range of custom needs.  Comparison with laboratory samplers show the SM4 to be quite accurate up to at least 3 GHz.

This screen capture shows the final result of my 1nS  pulser into the air, reflected back from a metal plate  (using a pair of Wavebounce TEM horn antennas) and received with this sampling head.

Additional technical details are available upon request.