The millimeter wave radiation of a dielectric leaky-wave antenna (DLWA) coupled with a metallic diffraction grating with a sinusoidal height profile is experimentally investigated. The interaction between dielectric and grating is contactless and it is from the broad-face of the dielectric line. The measured field patterns are compared with the simulated HFSS patterns. Antenna parameters such as polarization, HPBW, crosspolarization and side lobe levels are measured. The effects of the geometrical parameters of the grating to the radiation are also investigated. Some results are compared with a DLWA which has another diffraction grating profile shape (rectangular). The investigated antenna can be used as a frequency scanning antenna in mm-wave radars because it has low cross and side lobe levels and narrow beam width.

A travelling-wave long sinusoidal slot in the narrow face of a millimeter-wave (Ka-Band) rectangular waveguide is investigated. To the best of our knowledge, a slot of this shape is applied to the narrow face of a rectangular waveguide for the first time at this frequency range. The analytical study is based on the magnetic current model. Experimentally, far-field and S-parameters are measured and a good match is obtained between analytical and measured patterns. Frequency scan rates and velocity ratios of the structure are calculated. The effect of the sinusoidal slot's geometrical parameters (amplitude, period and number of periods) on the radiation patterns is also investigated. The drawback of the sinusoidal radiator is its cross-polarized beam that is not convenient for antenna applications. These co and cross-polarized beams scan in two different angle regions. To filter/suppress the cross-polarized beam, a grid polarizer is mounted to the sinusoidal slot and a 15 dB suppression level is reached. S-parameters measurement shows that the antenna efficiency increases remarkably after the application of the grid polarizer to the slot.

A dielectric leaky-wave antenna (DLWA) coupled with a metallic diffraction grating is experimentally investigated in millimeter-waves. The interaction between dielectric line and grating is from the narrow-face of dielectric and it is contactless. Measured patterns are compared with simulated ones. The antenna parameters (HPBW, side lobe levels, etc.) are also obtained. The most significant achievement of this antenna is to obtain broadside radiation without any suppression, which occurs due to the periodicity of grating. This situation is not available for the most of the periodic leaky-wave antennas. This antenna type can be used as a broadside radiator by this property as well as a frequency scanning purposes.

The radiation properties of a novel wire antenna are investigated. The main part of this antenna is a sinusoidal wire undulator, which radiates by coupling electromagnetic energy from a Goubau line located near the antenna. Far-field patterns and S-parameters composed of three sets of antenna are measured. The measured patterns are compared with the calculated ones and the phase and attenuation constants of all the antennas are calculated. Frequency behavior and the dependency on the antenna dimensions of those wave parameters are investigated. Measured and calculated field patterns are also compared with the MoM patterns and some properties of the wave propagating along structure are explained by using MoM current distributions. It is shown that a broadside transversal radiation occurs in a narrow frequency band. The radiation intensity strongly depends on the coupling distance between the Goubau line and the sinusoidal undulator. This antenna is used as the basic element of the security fence radar antenna array working at 1.25 GHz in the L-band, which detects intruders approaching the fence. The performance of the antenna in the array is investigated and the near field distribution of the array is measured. The received signals caused by an intruder are given. The effects of rain and wind are also considered. The results suggests that the security fence radar introduced in this study can be used for the perimeter control of closed areas such as airports, malls, etc.Index Terms-Border control, Goubau line, method of moments (MoM), modified or undulated wire antennas, security fence radar, sinusoidal structures, surface wave scattering.