# principal plane

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## principal plane

[′prin·sə·pəl ′plān]
(mathematics)
For a quadric surface, a plane that passes through the midpoints of all the chords perpendicular to it.
(optics)
Two planes perpendicular to the optical axis such that objects in one plane form images in the other with a lateral magnification of unity.
The vertical plane passing through the internal perspective center and containing the perpendicular from that center to the plane of a tilted photograph.

## principal plane

A vertical plane that contains the principal point of an oblique photograph, the perspective center of the lens, and the ground nadir. It is the vertical plane containing the optical axis.
References in periodicals archive ?
The principal plane of symmetry of surface B is no longer parallel with the HB plane passing through the point G = -b/3a.
Once the measured data for [E.sub.[theta]]([psi]) and [E.sub.[phi]]([psi]) are stored electronically, they can be post-processed to reconstruct the co- and cross-polarized components of the CP radiation pattern across that same principal plane cut.
For verification, the far-field radiation patterns are measured and plotted in two principal planes in Fig.
As explained in Section 5, by aligning the sources along the HMD direction the almost isotropic pattern in the H plane can be made directive; in particular, the same structure as in Figure 9 has been excited by an array of 21 HMD elements with interelement spacing d = [[lambda].sub.0]/10, in order to obtain the same 3 dB beam widths in both principal planes. The relevant radiation patterns are shown in Figure 10; it can be seen that the principal-plane beam widths are indeed equal (while the secondary lobes are higher in the H plane due to the uniform-amplitude excitation of the array).
Table 2 shows the edge power level of the principal planes at [theta] = 53[degrees].
Furthermore, the SRR causing suppression in XP does not affect any other characteristics like the co-polarized radiation over the principal planes, backward radiation, gain, and input impedance compared to those with conventional microstrip patch.
Tengs, "Corrugated soft sector horn with different beam properties in the two principal planes," Microwaves, Antennas and Propagation, IEE Proceedings, Vol.
Good broadside radiation patterns with low cross polarizations are observed in the two principal planes. For Port 1, the cross polarization level is -26 dB in the x-z plane and -31 dB in the y-z plane.
Total far-field radiation patterns of electromagnetically modeled antenna (# 5), in both principal planes of [phi] = 0[degrees] (x-z) and [phi] = 90[degrees] (y-z), are obtained at its simulated resonant frequency of 5.8GHz.
The radiation patterns of the antenna were measured in the principal planes at several frequencies in the cellular and GPS bands.
Figure 7 shows the normalized pattern in three principal planes (900, 1900, 2500 and 5500 MHz).

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