filter 506 is fed a signal from amplifier port 507 in this manner a signal from an amplifier passes through amplifier port 507 through waveguide filter 506 through two ports 506 a to four waveguides 505 each of which corresponds to a single antenna element 501 fig7 is a graph illustrating theoretically predicted e g using wipl d and nec advantages of a directive monopole antenna in directivity and both co polar and cross polar isolation according to one embodiment of the present invention as can be seen with reference to fig7 a directivity of 15 1 db reference no 701 can be achieved over a receive band of 14 0 ghz to 14 7 ghz while enjoying better than u2212 30 db of cross polarization reference no 702 relative to peak co polar over a range of scan angles from about u2212 10 u00b0 to about 10 u00b0 e g inside the scan angle of the earth disk from geostationary orbit fig8 is a graph illustrating theoretically predicted e g using wipl d and nec advantages of a directive monopole antenna in directivity and both co polar and cross polar isolation according to one embodiment of the present invention as can be seen with reference to fig8 a directivity of 15 1 db reference no 801 can be achieved over a transmit band of 11 7 ghz to 12 7 ghz while enjoying better than u2212 30 db of cross polarization reference no 802 relative to peak co polar over a range of scan angles from about u2212 10 u00b0 to about 10 u00b0 e g inside the scan angle of the earth disk from geostationary orbit fig9 is a graph illustrating experimentally confirmed advantages of a directive monopole antenna in directivity and both co polar and.