The excitation of electroacoustic waves by antennas in the ionosphere

Abstract

Measurements of the impedance at 7.75 Mc/s of an electrically short antenna in the ionosphere indicate that power is absorbed by some mechanism other than electromagnetic radiation. The importance of the radiation of energy as an electron pressure (electroacoustic) wave generated near the antenna is discussed, and it is shown that the calculated power radiated by this mechanism yields results in good agreement with the observations.

Interaction of an antenna with a hot plasma and the theory of resonance probes

“…. The prese nt almlysis and its conclusions differ [rom t hose of Whale [1963], who also co nsidered t be excitation of electrostftLic waves by introducinO' Lite co ncept of ftn isotropic pressure. ",Vhale assumed the existence of interaction between the fluctuatino' qu ftsi-electrostatic field (the near field of the electro~ magnetic waves) a nd t he electrostatic waves tbrouo'hout t he uniform plasma.…”

“…Antenna i mpeda nce measurements in t b e ionosph ere during rocket flights show t he prese nce of a much l arger resistilre component ["Whale, 1963] t han is predicted by t h e type of antenna t heory in which tbe surroundi ng plasma is t reftted as cold. J n principle the interaction of a n antennft with a h ot and very tenuous plasma should be treated by sol ving a combination of the collisionless Boltzmn,nn equ at ion with Maxwell's equations.…”

Impedance of a short dipole in a compressible plasma

“…Hall [1963] has obtained th e impedan ce of a pa rall el plate capac itor and F ejer [1964] has carri ed out a similar co mput ati on for a s in gle sp he ri cal elec trod e. Wa it [1964] has s tudi ed th e fi e ld of a slotted s ph ere and al so [1965] th e fi eld s of finit e a nd infinite cylindri cal dipol es. In additio n, Whale [1963], Mlodnosky and Garri ott [1962], and Crawfo rd and Mlodnos ky [1964] have es timated th e elec troaco us ti c effec t. on imp edan ce wh e n a n ion s heath is prese nt.…”

Theory of a slotted-sphere antenna immersed in compressible plasma. Part 1.

“…A theory wmch acco un ts for this phenomenon must take ~tCcoun t of th e finite compressibility of the electron fluid . Ther e is some evidence [Whale, 1963 th at r ocket-borne a ntennas excite electron-aco ustic waves in t he ion osphere. Unfortunately, the situation is complicated by th e presence of th e earth's magnetic fi eld and the existence of a pl asm~1 sheath around the an tenn a.…”