Construction Random wire antenna



a typical permanent wire antenna strung between 2 buildings. example has lightning switch ground antenna safety during electrical storms.


a random wire antenna consists of long (at least 1 quarter wavelength) wire 1 end connected radio , other in free space, arranged in way convenient space available. ideally, straight wire strung high possible between trees or buildings, ends insulated supports strain insulators. typically made number 12 or 14 awg (1.6 2.0 mm (0.063 0.079 in) diameter) copperclad wire. folding wire zigzag pattern fit in limited space such apartment or attic reduce effectiveness , make theoretical analysis extremely difficult. (the added length helps more folding typically hurts.)


if used transmitting, random wire antenna require antenna tuner, has unpredictable impedance varies frequency. 1 side of output of tuner connected directly antenna, without transmission line, other earth ground. quarter-wavelength sized wire works best, , unless fed through unun, half-wavelength exceed matching ability of tuners. without earth, antenna radiate, coupling capacitively nearby conducting material; nevertheless not recommended. ground random wire antenna may chosen experimentation. grounds returned nearby cold water pipe or wire approximately one-quarter wavelength long, or can replaced randomly laid-out quarter-wavelength counterpoise wires attached ground connection.


rf feedback, or ‘backlash current’, can issue. rf feedback can minimized selecting wire length causes low feed-point impedance @ current loop occur @ transmitter. alternately, remote tuner can fed feedline, , tuner located on antenna.








-

Comments

Post a Comment

Popular posts from this blog

Biography Pavel Yablochkov

yablochkov s demonstration of brilliant arc lights @ 1878 paris exposition along avenue de l opéra triggered steep sell off of gas utility stocks yablochkov’s major invention first model of arc lamp eliminated mechanical complexity of competing lights required regulator manage voltaic arc. went paris same year built industrial sample of electric candle (french patent № 112024, 1876). in paris developed arc light idea complete system of electric lighting powered zénobe gramme direct current dynamos fitted inverter supply single-phase alternating current. first public use of yablochkov system in october 1877 @ halle marengo of magasins du louvre lit 6 yablochkov candles. 1880, system had grown in size 120 lamps 84 lit @ time powered 100-horsepower steam engine , had been operating every night 2 , 1 half years. the paris exposition of 1878 presented yablochkov unique opportunity make spectacular demonstration world audience, , through promotional efforts of gramme successful in having 6...
Read more

Discography Three Man Army

1 discography 1.1 third of lifetime (pegasus records, 1971) 1.2 mahesha (issued in 3 man army) (reprise/polydor, 1973) 1.3 3 man army 2 (reprise/polydor, 1974) 1.4 3 man army 3 (revisited records, spv 304222cd - recorded 1973-4 released 2005) discography a third of lifetime (pegasus records, 1971) track listing bonus tracks personnel adrian gurvitz - guitar, vocals, organ, mellotron paul gurvitz - bass (all 5), vocals mike kelly - drums (all 1) buddy miles - drums (1), bass (5), organ (9) mahesha (issued in 3 man army) (reprise/polydor, 1973) track listing all tracks written adrian gurvitz, except noted. personnel adrian gurvitz - guitar, vocals, keyboards paul gurvitz - bass, vocals tony newman - drums three man army 2 (reprise/polydor, 1974) track listing personnel adrian gurvitz - electric , slide guitars, vocals, organ paul gurvitz - bass, vocals, acoustic guitar tony newman - drums peter robinson - piano (4, 6) doris troy - backing vocals (6) madelin bell - backing vocals (6) ruby...
Read more

History VMFA-121

1 history 1.1 world war ii 1.2 korean war 1.3 vietnam war 1.4 gulf war & 1990s 1.5 global war on terror , beyond 1.6 f-35b lightning ii joint strike fighter era history world war ii squadron s logo when vmf-121 marine fighting squadron 121 (vmf-121) activated on june 24, 1941. green knights began combat operations flying f4f wildcat , later f4u corsair charter members of cactus air force , throughout battle of guadalcanal. squadron fought forward air bases of espirito santo, turtle bay, bougainville, , emirau. on september 15, 1944, green knights landed on peleliu , fought there until july 25, 1945. returned united states deactivated on september 9, 1945. during pacific war, vmf-121 produced fourteen fighter aces, more other squadron, including medal of honor recipient, major joseph j. foss. vmf-121 downed 208 japanese aircraft (165 flying wildcats , 44 flying corsairs) in aerial combat. after world war ii, squadron reactivated in united states @ naval air station glenview, illinoi...
Read more