Compact wideband multiple conductor monopole antenna

Claim 2

In an antenna employed for the transmission of different frequency radio signals and including a first cylindrical conductor of length h 1 , the conductor resonating at frequency f 1 for which h 1 is approximately one-quarter of a wavelength, that is, h 1 ≈λ/4 at f 1 ; means for generating a current distribution in the antenna, when the antenna is operated in a band extending from f 1 to 4 f 1 , that approximates the current distribution of a monopole whose physical length is approximately one-quarter of a wavelength at all frequencies in the band, said means for generating a current distribution in the antenna including: a plurality of second cylindrical conductors positioned parallel to and spaced from the first conductor; the length of each second conductor being one-quarter of a wavelength at a respective frequency in the band; and a plurality of resistors; each resistor connecting an end of a respective second conductor to one other conductor; the second conductor forming balanced two-wire transmission line traps with the conductors to which they are connected.

Claim 3

The antenna recited in claim 1 wherein: the plurality of second conductors lie on and define a cylindrical surface whose axis of revolution coincides with the longitudinal axis of the first conductor and whose radius D is very small compared to a wavelength at any frequency in the band; whereby the antenna diameter is confined to a small value so that the antenna is compact.

Claim 4

The antenna recited in claim 2 wherein: each second conductor has, with respect to the one other conductor to which it is connected, a balanced two-wire transmission line trap characteristic impedance Z 0 , and all values of Z 0 are the same; each resistor has a resistance R, and all values of R are the same and approximately proportional to the value of Z 0 .

Claim 5

The antenna recited in claim 3 wherein: the first conductor has a feedpoint; the second conductors are seven in number and have respective lengths h.sub.2 =λ/4 at 1.33 f.sub.1 h.sub.3 =λ/4 at 2 f.sub.1 h.sub.4 =λ/4 at 3 f.sub.1 h.sub.5 =λ/4 at 4 f.sub.1 h.sub.6 =λ/4 at 3 f.sub.1 h.sub.7 =λ/4 at 4f.sub.1 h.sub.8 =λ/4 at 4 f.sub.1 the second conductors whose lengths are h 2 , h 3 , h 4 and h 5 are connected to the first conductor at the feedpoint with their connected ends lying in a plane normal to the first conductor at the feedpoint; starting with the second conductor of length h 5 and referencing its location in the plane normal to the first conductor at 0°, the second conductor of length h 4 is at 90°, the second conductor of length h 3 is at 180°, and the second conductor of length h 2 is at 270°, the second conductor whose length is h 6 is connected to the first conductor and aligned with the center one-third of the first conductor; the second conductor whose length is h 7 is connected to the first conductor and aligned with the third one-quarter of the first conductor measured from the feedpoint; the second conductor whose length is h 8 is connected to the second conductor of length h 2 and aligned with the center one-third of the second conductor of length h 2 ; and the projections in the plane normal to the first conductor of the second conductors whose lengths are h 6 , h 7 and h 8 lie respectively at 315°, 45°, and 225°.