... AVIATION RADIO COURSE by PAUL W. K iRROL Part 4. The development of antennae for aircraft has increased the effective range in all services. N aircraft radio installation is craft antennae. These are: the belly light. It is used mainly for the re- only as efficient as its antenna T; the vertical mast; the V; the wing ception of radio range signals, is very systems. No matter how well tip to wing tip; the T; the loop; and non -directive and is sometimes used designed the receiver, transmitter, and the multi- frequency and trailing wire as a supporting mast for the wing tip associated equipment may be, if the antennae. to wing tip antenna, an insulator be- ...
... the plane, suspended on either masts Common antennae (used for both or sub -masts to effect a clearing. The transmitting and receiving) are em- vertical antenna seems to be the "out" ployed to a very large extent. An as far as absorption losses are con- antenna relay which switches the com- cerned. mon antenna between both receiver The dielectric losses and conductor and transmitter must be used. When losses should be a small influence the transmitter is operating one con- upon the effective radiation resistance tact of the relay automatically shorts of the aircraft antenna; impedance out the receiver input. In some re- should be the influencing factor. So lays one contact shorts out the input when designing the antenna, the ...
... determined for this station, together tennas upon the third must be con- with the antenna arrangement is E3, E, E3 = voltages applied to antennas sidered in the most direct and prac- I, = currents flowing in antennas shown in Fig. 3. This pattern was tical manner. Z11, Z,, ZZ = self impedances of antennas = mutual impedances be- decided upon as desirable for the dou- When an antenna is driven so that Zu, Z13, ble purpose of avoiding interference tween antennas it has current flowing in it, an in- with co -channel stations and at the duced voltage will exist in any other When applying equation (4 ) , it is same time beaming a maximum sig- antenna in the ...
... depth range of the is a third Fisher circuit, which has never Receiver, and one type -31 tube in the trans- transmitter; this gives a depth range of over been placed on the market commercially. mitter. It has a filament voltmeter; filament 20 feet which is sufficient for locating most This uses only three tubes, and employs rheostat; a balanced loop antenna which buried treasure. Operating the batteries four only the one double -loop, instead of separate eliminates body and ground capacity; a hours a day, they should last three to four loops for the transmitter and receiver. portable type 45 -volt B battery, and two type months, which shows that this set is de- Whichever set you build, you can be ...
... S -T TELEVISION LINK ANTENNA By B. P. MOWN Electronics Dept. General Electric Co. Problems encountered in the design of a studio -transmitter television link antenna. BEFORE considering the actual tional beam so as to concentrate the constructional and electrical de- radiation in the direction of the main tails of the S-T Television link transmitter location. This, of course, antenna system described here, per- is for the purpose of utilizing the power haps it is desirable to first review the fed into the link antenna most effec- electrical requirements necessary for . tively by reducing its radiation in di- satisfactory operation of a link anten- rections not toward the receiver at the na system which would be suitable for main transmitter. In addition, the ...
... KDKA — Radio's New Voice One of the most important innovations (Continued from page 873) end of a transmission line, except that the is the new tube with a capacity of 200 lines of force are not guided by wires, kilowatts. This tube is not merely an The antenna system of the new KDKA and hence follow the ordinary law of enlarged edition of a smaller tube, but radio transmitting station, conceived by equal angle of incidence and reflection. is thoroughly engineered as a tube of Dr. Conrad, is designed to make the lo- There is really no line of demarcation be- larger size and of a distinctly novel de- cal signal strength less than it would be tween the ground wave and the upward sign ...
... This may be visualized mathematically mitter practice this ratio must never as: exceed 5% , thus it becomes apparent from the graph of Fig. 3 that the con- S/N1 D1 ventional type of antenna is com- S/N2 (61 pletely inadequate for television trans- D2 mitting systems. The conical antenna is the only one shown on the graph en- where N is the noise signal strength. tirely suitable for the purpose, al- The S/N improvement may be seen to though folded dipoles arranged in a be equal to directivity gain. It may be concluded from the above arguments that : 1. the chief design problem is the attainment of high signal to interfer- ence ratios, 2. high ...
... small as well as large aircraft for both transmitting and receiving is the V antenna. It is sometimes called the BRACKET OFT. "flat -top" and sometimes referred to INSULATOR ROTATABLE LOOP as the "split V," and is suspended be- tween one wing tip to the rudder to the other wing tip by means of in- E i y ' ELECTRICALLY UNUSE ,PORTION (MAY BE AT EITHER END) STUB MAST LOOP AZIMUTH CONTROL BOX sulators attached to shock cord or I __ LOOP ELECTRICAL PANEL AND CONTROL BOX UNITS spring and pulley assemblies. Where HOUSING it is desired to use the V for both MECHANICAL LEAD- TN (DROPPING VERNALLY L -R COURSE transmitting and receiving (and when CONTROL CABLES INDICATOR no antenna relay is employed ...
... 1.6 explained in complete detail further on. VERTICAL ANTENNA RESULTANT 1.41 OR 100 ! . HORIZONTAL ANTENNA The transmitting antenna consists of SINE e LOAiAMPLIFtER SINE e a half -wave, horizontal dipole, open - 1.4 1.41 1.41 center fed with a tuned feeder line ap- OR 71% LOAD ON AMPLIFIER OF 71% LOAF ON AMPLIFIER proximately one -quarter wavelength 1.2: long. The dipole was erected one -quar- ter wavelength above the earth so that the incident angle from it, alone, would 1.0 be at a very high angle or about 90 de- grees in respect to the earth's plane. .8 This same dipole, together with its feed line, was employed as a top -load- .6 ed, vertical antenna, with an excita ...
... will be noted that at the instantaneous side of' the zero axis, ammeters Al and The Dispersion positions marked "Y " on the horizon- A2 will read equal values of effective Transmitter tal- antenna current curve, the verti- currents. Therefore, it is obvious that (Continued from page 30) cal- antenna current is zero. This be- the current falls in one antenna as it ing the case, there is no interference rises in the other. The radiated fields A2 will not read alike. Consider a con- due to the vertical -antenna current are lower in one while they rise in the dition where the phase displacement is and the composite antenna operates as other and vice versa. The combination zero or ...
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