A 500-W coupled-cavity TWT for Ka-band communication

Commun. & Power Industries, Palo Alto, CA, USA
IEEE Transactions on Electron Devices (Impact Factor: 2.47). 06/2005; 52(5):665 - 668. DOI: 10.1109/TED.2005.845867
Source: IEEE Xplore


Worldwide demand for high-power amplifiers for digital satellite communication at Ka-band frequencies between 27 and 31 GHz is steadily increasing (2003). Communication and Power Industries (CPI) has developed a 500-W periodic permanent magnet focused coupled-cavity traveling wave tube (TWT) for conduction-cooled amplifier systems, which is being introduced into the commercial satellite communication market. The TWT is capable of greater than 500-MHz instantaneous bandwidth and is cathode voltage tunable from 28.3 to 30 GHz. The TWT may be operated saturated at the 500-W output power level or backed off from saturation in the linear mode. CPI's Satcom Division has integrated the TWT into a conduction-cooled transmitter box suitable for antenna hub-mount applications. The amplifier uses predistortion networks to provide a high degree of linear response when operated in output power back-off mode.

1 Follower
21 Reads
  • Source
    • "In this paper, we present the design and simulation of a Ka-band double-slot staggered CCTWT based on CPI's CCTWT [4] by using the 3-D PIC code MAGIC3D in order to investigate and understand the beam dynamics in the CCTWT. We simulated the Ka-band CCTWT in [4] by using similar parameters such as beam voltage, beam current, and slowwave structure dispersion characteristics. MAGIC3D is a 3-D, fully dynamic, and self-consistent PIC code used to simulate plasma-physics problems [15]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The 3-D particle-in-cell (PIC) simulations of a Ka-band coupled-cavity traveling-wave tube (CCTWT) are shown. The computational analysis of the Ka-band coupled-cavity slow-wave structure was conducted through the use of an electromagnetic PIC code MAGIC3D. The choice of a double-slot staggered RF cavity circuit was made because of a wide frequency bandwidth, moderate interaction impedance, and excellent thermal dissipation properties. We investigated the large-signal and nonlinear beam dynamics of a Ka-band CCTWT using MAGIC3D. The center frequency of the Ka-band CCTWT can be tuned from 28.4 to 30 GHz by varying the cathode voltage. Hot-test simulations show that the 84-cavity Ka-band CCTWT produces 540 W of saturated output power at 29 GHz with an electronic efficiency of 8.1% and a gain of 28 dB when the beam voltage and current are set to 17 kV and 390 mA, respectively.
    IEEE Transactions on Electron Devices 02/2009; 56(1-56):149 - 155. DOI:10.1109/TED.2008.2008711 · 2.47 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Boeing EDD continues to make advances in its millimeter-wave helix-TWTs by pushing the CW output power capability and increasing the overall efficiency of Ka-band and Q-band devices for communications. The 8921HP, EDD's latest high power Ka-band TWT model, demonstrates 250 W to 300 W CW output power and 47 % minimum overall efficiency with a two-stage collector over 27.5 GHz-31 GHz. In Q-band, the 8925HP, derived from the current production 120 W Q-Band helix-TWT (8905HP), significantly extends the CW output power capability demonstrating 230 W minimum over 43.5 GHz-45.5 GHz. The beam focusing is improved in both the Ka-band and the Q-band TWT models, with RF beam interception well below 1% of the nominal beam current of 95 mA. The above devices are primarily designed for CW operation but can also be operated in pulsed mode by using the focus electrode to cut-off the beam. The electron gun typically requires a focus electrode voltage of -800 V with respect to the cathode for beam cut-off.
    Vacuum Electronics Conference, 2004. IVEC 2004. Fifth IEEE International; 05/2004
  • [Show abstract] [Hide abstract]
    ABSTRACT: Predistortion linearization is a very effective technique for improving the linearity and efficiency of traveling wave tube (TWT) amplifiers. In this paper, we will study the effectiveness of predistortion techniques for TWT linearization using single-tone, two-tone, and quadrature-amplitude-modulation signals. The results from a series of predistortion linearization experiments for five TWTs covering L-, C-, Ku-, and Ka-bands and including both helix- and coupled-cavity TWTs will be presented. We will demonstrate the additional improvement of fifth-order predistortion linearization over the more commonly used third-order predistortion linearization. To circumvent the complexity and limited availability of a pure fifth-order linearizer, a technique for realizing nonlinear functions of order greater than or equal to five using cascaded third-order nonlinear functions is described. The technique can be used to efficiently generate higher order nonlinearities for predistortion linearization applications. We will demonstrate experimentally that the use of two cascaded third-order functions is comparable to a pure fifth-order implementation in performance.
    IEEE Transactions on Electron Devices 06/2005; 52(5-52):718 - 727. DOI:10.1109/TED.2005.845838 · 2.47 Impact Factor
Show more