Show 4 A ca 1112 HOW AN INDOOR LOOP ANTENNA IS BUILT has advantages in size andal and directional ional properties but picks up little energy a 7 if you live in a section of the conn coun try infested sted u with ith rad 0 fans ft ia I 1 0 send or send some station call by the hour while you are trying to catch tue the music from a broadcasting station a loop antenna may I 1 elp solve your difficulty or it if you live la in an apart ment or a very cong congested sted section of the city where there is no room to erect an antenna or where the land lord objects a loop antenna can be used in lieu of an outdoor one let t it be thoroughly understood however J anwa 4 13 6 all 7 ca y that the energy picked up by a loop antenna only approaches that of an outdoor antenna when the physical dimensions limen of the loop antenna ap those of tl if e outdoor antenna don t wind a hundred feet of wire on a it mothers mother s oats box and expect a loop antenna so constructed to give the he same signal s bength as tl e same hundred feet of wire m ire stretched str etchel tebe I 1 out side as a single wire out outlook loor antenna TI tie e two advantages of a loop an tenna then are its small dl ill mens lons and its directional proper ties the most serious d of the loop antenna is tl ti e small amount of energy ed up if loop antenna Is used for the reception of close hibb pa p A ered stations station s or I 1 nary regenerative receivers v w th aud 0 fre quency amplifiers will give good results however if a long ll li stance reception of med im and low po ier er transmitting stations Is desired then radio frequency amplification must be used ti ere has been place plate I 1 on the I 1 i arket i a radio ficq implying amp fi ing arins former type UC 1714 to be he ustin I 1 conjunction with alth type UC such a co c I 1 I 1 fotion Is claimed to give an audibility amplification of 20 per stage A loop antenna with a two or three singe stage a it i lio ito frea aepli fler employing tipe coupling transformers it in conjunction with one 8 present set nil RII give glae practically the same signal strenge i that Is no v being received frore the outdoor antenna though a loop antenna of larger section and tc feier i er turns would be more directional the antenna deser bed here will give good res ailts for its s ae fin annl I 1 Is small eno gh to I 1 e easily enns ported the material lire tire I 1 for the two iop antenna Is as follows fol loNs two strips strip of wood Vs feet ions lonz by hv 2 inches wide I 1 v 1 inch thick straight ht close grained wood should he used in order to guard against warping one h indred feet of no 14 hire an tenna wire preferably stranded chor bronze four pieces of bil bit elite 2 inci es square by inch tl ti ick four small brass angles of the type that can cante lye purchased in the 5 and 10 e cent stores one dozen 1 inch long 6 32 brass ay machine screws ath w th nuts notch the ta two 0 preces of v wood in the center and at the ends as shown in figure III then with a 10 Is 25 drill bore three holes in each piece of wood as shown the n tel es in the center part of the two pi ces of wood should 1 ballow I allow the two pie es to be fitted to gether to form a perfect right angle the notches should be just wide enough so that on of the four 2 inch square pieces of bikelites bik elite will just fit after the notches have been cheel ed ato rito see that thy art of tl ti e proper size fit tie tl e two strips of wood er I 1 lutting lifting a little furniture glue in the joint and belting it fast with a long bolt the brass ai at agles should now be fitted in the corners of the joint to male mal 0 the two strips of wood form a right angle to prevent warping ind tor for the sake of appearance tl e wood ft orb ork should be given several coats of shellac the natural period of this loop an tenna la Is approximately meters to tune to wave lengths in excess of meters a microfarad con dinsel Is shunted across the leads of the loop the closed oscillating circuit formed by the loop and the shunt condenser can be connected by any detecting circuit as shown in rig fig I 1 or can be used with radio frequency amplifiers when used with retelling rei ret elving sets employ ing a varlo couple and two vario meters the loop Is connected and the shunt condenser Is omitted the tuning Is accomplished by means of the grid varl ometer A loop antenna will pick up a maxi mum amount of energy when the station Is in the plane of the loop and and a in amount of ex ei gy when if tie e transmitting station Is in a direction at right angles to the plane of the loop in rig fig II 11 the loop will pick up a maximum amount of energy from station A and a minimum amount from station B care must be taken in setting up a loop to see that it will not be shielded the energy picked up by a loop an tenna Is small at best especially if the loop Is not oriented to its maxi m mum u m pa pos s tion and any reduction in received e c elved energy will debease decrease the sig nala nals below aud and billay for example dan dent t set up a loop antenna inside a steel flamed building or up in the attic directly under a well grounded metal roof capacity effect due to the body of the operator Is qu te noticeable with a loop antenna ahe I 1 he operator must not get close to the loop or the ca lacity effect of his body will detune the oscillating circuit IN I 1 ile if tie e loop is rati er difficult to handle in some instances and cin only be used to replace an art outdoor antenna at a loss in ill ie elved energy its directional proper ties are very advantageous in the reduction of interference TIPS TO THE the danger of stringing radio wires over light or power wires was demonstrated in new jer sey recently wl en a nv ell I 1 no C was shocked to death radio distance lends end encl ant ment A wilter vilter says A g eat many amateurs prefer to hear a few discordant no es from 1000 les away than a wonderfully executed program from their own oven ton to nn radio accomplishes some great and new tl if ing every day no v it has been found that old blades can be used in making condensers aid arl agoti er way uny to get rid of old blades Is given to a grateful public radio I 1 as gone to the dogs A hood fiver river ore piper de es a toy dog witt his till caught in a upon cill call ng here tige tie olce voice abia eions jelense the trap and tl e pup springs at you one of the latest inventions in the ra lio field Is a filter tl ti it separates the telephone ani tel evgraph anva eg we it i I 1 forward to the day when a filter I 1 will se pirate tl e goodus c from tie it e bid and 9 ton t 0 n t cally send tl it e latter to uranus I 1 in boring or sd sa n wood fiber etc soap Is fir better tian 0 an oil also if screws ire soaped with old nary I 1 ltd iti en soap they AN will ill enter tl tie e v x 0 ol 01 I 1 easly aas ly without ditl out danger of r aln ing tl e head slots an I 1 mo ino e oer over tl ey may be readily ie moed moved at any time dr marconi lives a life of clock work regularity upon I 1 I 1 macit t lie he breal fasts at 8 in I 1 tolerates no tard ness on tl it e part of those dining with I 1 fi fir i he ile Is an indefatigable NN iker and holds hin self in rei ren linens liness to give personal on to any ra radio dlo matters tl at maa ma come up night or daj dean dexter S 8 bhul al of cor nell anh era ty in a recel t till I 1 q I 1 talk to engineers made two in 11 I 1 points one that i 1 min can no DO v say I 1 II 11 tell the i orl I 1 without using slang and the other tint the stu sauly ly of eti etl ei ez i orations brat lons ions upon which anlo n 1 I 1 based Is in its infancy and tl e t future promises even moie tl it n the development from manu I 1 signs to radio A aa A |