The cavity is excited by a coupling probe at the common broad wall which is used to couple energy in the SIW main transmission structure into the resonator, with a circular slot around to separate it from the SIW inner metal plane.
The coupling probe is isolated from the SIW lower conductor planes through an annular slot that results in a circular disk around the coupling probe.
The dual-orthogonal linear polarizations are generated by an L-shaped coupling probe
and an H-shaped coupling aperture.
It does not require any complex feeding structure and uses only a coaxial feed extended with a simple electric field coupling probe. The corners of the horn are truncated to generate CP modes, and a broad axial ratio bandwidth which is insensitive to the probe feed dimension is achieved.
The input is a coaxial feed extended with a simple electric field coupling probe. The cross section of the truncated horn antenna is similar to a single feed truncated microstrip antenna [11-13].
The electric field coupling probe is approximately [lambda]g / 4 from the short circuit wall and it is used to excite the waveguide modes.
Microwave energy was introduced to the cavity through a coupling probe .
The cavity length and the coupling probe length were tunable.
Finally, if the dip levels of the [N.sub.x] patch (with the radiating power [Pr.sub.n] (n = 0...[N.sub.x-1])) of the linear array coupling probes in the waveguide obey Equation 4 ( see Figure 7), then this array provides the required side lobe levels of -28 dB.
The antenna tests have demonstrated high agreement between measured and calculated values of propagation constant in partially dielectric-filled waveguides and coupling probes (the measured deviation angle of the beam coincide exactly with the calculated one), SWR, gain and pattern parameters.
The coaxial probe coupling method uses coaxial coupling probes
over microstrip, coplanar or waveguide coupling structures, and provides a method for evaluating structures similar to actual microwave circuit applications.
In the case of longitudinal oscillations on the conducting strip, depending on the strip length and the number of standing half waves, it is possible that a voltage zero might appear directly underneath one or both of the coupling probes
. Since the coupling is capacitive in nature, a voltage zero at the probe position would not allow any energy to be coupled from the excitation probe to the test line or from the test line to the detection probe.