SPS Feasability Study SD76SA0239-2

3. Simpler structure which allows the RCR to be integrated with the RF tube to alleviate the thermal interface problem. RCR Theoretical Attenuation Estimates The loss mechanisms of the RCR can be best explained by comparison to conventional arrays. The typical flat plate antenna array is formed by placing side-by-side several sections of rectangular waveguide as shown in Figure Figure 2.3-7. Figure 2.3-7. Typical TEiq SWR Array The mode that propagates down each waveguide is the dominant TEiq* The mode designation simply describes a particular electric-magnetic field configuration that satisfies Maxwell's equations. A portion of the top wall in waveguide No. 2 in Figure 2.3-7 is cut away to show the current flowing in the side wall. Not shown is the adjacent currents flowing in waveguide No. 1. These currents (waveguide No. 1) are flowing in the opposite direction and because the system is symmetrical, they are of equal magnitude. If the side walls are removed as in the RCR, these two equal and opposite currents cancel. Since conduction losses are simply I^R losses, any reduction in surface currents will make the antenna array more efficient. The close-form analytical expression for conduction losses for silver- plated RCR supporting the TEm>o modes is given as: For an a dimension of 4.460 inches and a b dimension of 2.130 inches (11.319 cm by 5.40 cm) the loss calculated from the above equation is tabulated in Table 2.3-2. This shows that for a typical array length of 2.5 meters, a TE7Q RCR has the potential of saving 4.3 x 10$ watts of power. Weight savings in the MW antenna is achieved by two design features: (1) the RCR is designed with no side walls with the exception of the cavity walls,