Circularly polarized, broadside firing tetrahelical antenna
AssigneeRCA Corporation
InventorOded Ben-dov
Life of this patent
Estimating the term…
Abstract
An antenna for radiating circularly polarized signals omnidirectionally about and broadside a support mast is provided by four conductors helically wound about the mast. The conductors are spaced from the mast and are equally distributed about the periphery of the mast with signals coupled to the conductors such that the phase of the signal coupled to one conductor is 180.degree. out of phase with the phase of the signal coupled to adjacent conductors and is in phase with the phase of the signal coupled to the alternate conductor. The pitch of the helically wound conductors is selected relative to the radius of the conductors to achieve substantially circularly polarized radiation substantially perpendicular or broadside to the lengthwise axis of the mast.
Claims7
An antenna for radiating circularly polarized signals over a given range of frequencies omnidirectionally about and broadside a support mast comprising:
- four conductors helically wound about and spaced from the support mast a given radial distance from the center of the support mast with each conductor of said four conductors spaced about 90.degree. of arc about the support mast from the adjacent two of said four conductors.
- means for coupling equal power signals at the same frequency within said given range of frequencies to said four conductors so that in a plane perpendicular to the axis of the support mast the phase of the signals at one of said four conductors is 180.degree. out of phase with the phase of the signals at the two of said four conductors adjacent thereto and is in phase with the phase of the signals at the one of said four conductors alternate therefrom,
- said four conductors at a pitch angle and at a given radial distance such that each of said four conductors makes a complete turn about said support mast in a length along said four conductors about equal to two wavelengths at a frequency within said given range of frequencies whereby circularly polarized signals are radiated substantially broadside said support mast.
An antenna for radiating circularly polarized signals over a given range of frequencies omnidirectionally about and broadside a support mast comprising:
- four conductors helically wound about and spaced from the support mast a given radial distance from the center of the support mast with each conductor of said four conductors spaced about 90.degree. of arc about the support mast from the adjacent two of said four conductors,
- means for coupling equal power signals at the same frequency within said given range of frequencies to said four conductors so that in a plane perpendicular to the axis of the support mast the phase of the signals at one of said four conductors is 180.degree. out of phase with the phase of the signals at the two of said conductors adjacent thereto and is in phase with the phase of the signals at the one of said four conductors alternate therefrom,
- said four conductors extending at a pitch angle relative to said given radial distance to radiate circularly polarized signals substantially broadside said support mast,
- said pitch angle .psi. for said given radial distance approximating the following relationships ##EQU4## where .psi. is the pitch angle, R is the radius of the helix formed by the conductor, .gamma..sub.0 is a free space wavelength at a frequency within said given range of frequencies, J.sub. 1 is a Bessel function of the order of one and J.sub. 2 is a Bessel function of the order of two, .gamma. is the propagation constant along the helical conductor, and k is 2.pi. /.lambda..sub.o.
Dependencies are inferred from the claim text.