United States Patent 3,950,757 Blass April 13, 1976
Broadband whip antennas
2.Abstract A whip antenna with a substantially constant impedance over a broad band of radio frequencies includes a mounting section, a high-power-dissipation low-resistance assembly, a first whip section, a second whip section, and a high-impedance quarter-wavelength transformer section concentrically formed around the first whip section and extending from the resistance assembly to the junction of the first and second whip sections. The low-resistance termination is attached close to the base of the antenna and is transformed to a high resistance at the junction of the first and second whip sections at the frequency where the matching section length equals one quarter-wavelength. The resistive power loss only occurs over a limited band centered at the design frequency of the matching section. Instability caused by emplacement of a high-mass resistive termination towards the top of the complete antenna is thus avoided.
Inventors: Blass; Judd (Herzliah Petuach, IL) Assignee: Beam Systems Israel Ltd. (Nof Yam, IL) Appl. No.: 05/557,836 Filed: March 12, 1975
United States Patent 4,028,704 Blass June 7, 1977
Broadband ferrite transformer-fed whip antenna
Abstract The feed point of a whip antenna having a length less than one quarter-wavelength at the lowest frequency of operation is raised above a counterpoise ground plane by a short base sleeve. Gain over a 2.5:1 bandwidth of radio frequencies closely approaches the gain of a standard quarter-wavelength antenna without requiring use of power-dissipating resistance loading. A ferrite transformer at the whip antenna feedpoint is utilized to reduce the high anti-resonance impedance of the broadband whip antenna to the characteristic impedance of a coaxial cable transmission system and to minimize the VSWR thereof. The base sleeve raises the antenna resistance at the resonant frequency near the lower end of the bandwidth to make the transformer effective as an impedance matching element over the entire radio frequency band. A pair of the whip antennas are axially aligned and electrically coupled in series to realize a broadband dipole having increased gain. A pair of dipoles are energized in phased relationship to realize even higher gain and directivity.
Inventors: Blass; Judd (Herzliah Petuach, IL) Assignee: Beam Systems Israel Ltd. (Nof Yam, IL) Appl. No.: 05/605,338 Filed: August 18, 1975