534 Sine vibration was performed to qualify the strength of the FWG for  its expec ted flight levels, 15 G  in the  spacecraft lateral axes and 20 G  in spacecraft thrust axis. Any resonance response was limited to 36 G   according to its  mass -acceleration limit load. The strength verification was accomplished by applying a  sinusoidal vibration at the qualification level in the frequency range less t han resonance so that the  acceleration load approximated a static loading. All waveguides passed this test and demonstrated the  capability  to handle expected launch loads. The maximum response recorded was 37 G  after notching  (Figure 6). 

Random vibration t esting was performed on the FWG s to the protoflight levels . The development  and flight  batch qualification waveguides were exposed to a random vibration input of 6.3 Grms  in the wide section  direction, and the max imum  overall response recorded was 16.8 Gr ms (Figure 6) . At 3σ, the acceleration  response would be 50.4 Grms , indicating that the waveguide could withstand loads higher than the design  limit of 36 g.  In spite of the large responses seen in the tests, the w aveguide is relatively light (40 grams),  and therefore the load supported in its own structure during vibration is less than 22 N . 

Figure 6. Vibration Test Responses  

Another area of interest was to assess the tolerance of the FWG to axial loads, either due to installation  misalignments or on- orbit thermal mismatch. The maximum estimated extension with margin, due t o all  possible sources was about 0.7 mm. One of the development model waveguides was subjected to   300 cycles of extension on a Universal Testing Machine and the load was monitored. For this extension,  the waveguide was within the elastic limit and the load at maximum extension remained stable at 1.42 N.  The waveguide was also subj ected to compression, the waveguide flexed slightly  to accommodate this  with  very lit tle change in load.  

Thermal Concern   A few  thermal concerns with the us e of the flexible waveguide were identified during the development phase  of this program. They  were further explore d through analysis and test, resulting in design changes to both  the HGA and the FWG .  

One of the key concerns was  that the geometry of the FWG  could cause the middl e section of the  waveguide to become very hot. The waveguide had a relatively small cross- section and a large distance   between the middle section and the flanges. The flexible part of the waveguide was very thin, and the  corrugated path of this section created an effect ive conductive length that was several times the actual  length of the waveguide assembly . Given that thermal resistance increases with length and decreases with  area, the middle of the waveguide was thus strongly thermally isolated, in spite of being made from Ni -Co  metal alloy . Even if flange temperatures were to be controlled, there still could be a very high temperature  in the cen ter of the waveguide due to power  dissipation during RF transmission. Adding to the concern with  the middle temperature of the waveguide was the fact that this portion of the w aveguide could be exposed