chithunzi 1
1. Kugwiritsa ntchito bwino kwa denga
Chinthu china chodziwika bwino chowunikira ubwino wa ma antenna otumizira ndi kulandira ndi mphamvu ya kuwala. Pa antenna yokhala ndi lobe yayikulu mbali ya z-axis monga momwe zasonyezedwera pa Chithunzi 1, mphamvu ya kuwala (BE) imatanthauzidwa motere:
Ndi chiŵerengero cha mphamvu yotumizidwa kapena yolandiridwa mkati mwa ngodya ya koni θ1 ku mphamvu yonse yotumizidwa kapena yolandiridwa ndi antenna. Fomula yomwe ili pamwambapa ikhoza kulembedwa motere:
Ngati ngodya yomwe mfundo yoyamba ya zero kapena mtengo wocheperako umawonekera yasankhidwa ngati θ1, mphamvu ya beam imayimira chiŵerengero cha mphamvu mu lobe yayikulu ndi mphamvu yonse. Mu ntchito monga metrology, astronomy, ndi radar, antenna iyenera kukhala ndi mphamvu ya beam yapamwamba kwambiri. Nthawi zambiri pamafunika kupitirira 90%, ndipo mphamvu yomwe imalandiridwa ndi lobe yam'mbali iyenera kukhala yochepa momwe ingathere.
2. Bandwidth
Bandwidth ya antenna imatanthauzidwa ngati "ma frequency range omwe magwiridwe antchito a makhalidwe ena a antenna amakwaniritsa miyezo inayake". Bandwidth imatha kuonedwa ngati frequency range mbali zonse ziwiri za central frequency (nthawi zambiri kutanthauza resonant frequency) komwe makhalidwe a antenna (monga input impedance, directional pattern, beamwidth, polarization, sidelobe level, gain, beam pointing, radiation efficiency) ali mkati mwa range yovomerezeka mutayerekeza mtengo wa central frequency.
Pa ma antenna a broadband, bandwidth nthawi zambiri imafotokozedwa ngati chiŵerengero cha ma frequency apamwamba ndi otsika kuti agwire ntchito moyenera. Mwachitsanzo, bandwidth ya 10:1 imatanthauza kuti ma frequency apamwamba ndi ochulukirapo ka 10 kuposa ma frequency otsika.
． Pa ma antenna a narrowband, bandwidth imafotokozedwa ngati peresenti ya kusiyana kwa ma frequency ndi mtengo wapakati. Mwachitsanzo, bandwidth ya 5% imatanthauza kuti ma frequency ovomerezeka ndi 5% ya ma frequency apakati.
Chifukwa makhalidwe a antenna (input impedance, directional pattern, gain, polarization, etc.) amasiyana malinga ndi kuchuluka kwa ma frequency, makhalidwe a bandwidth siapadera. Nthawi zambiri kusintha kwa directional pattern ndi input impedance kumakhala kosiyana. Chifukwa chake, directional pattern bandwidth ndi impedance bandwidth ndizofunikira kuti zigogomeze kusiyana kumeneku. directional pattern bandwidth imagwirizana ndi gain, sidelobe level, beamwidth, polarization ndi beam direction, pomwe input impedance ndi radiation efficiency zimagwirizana ndi impedance bandwidth. Bandwidth nthawi zambiri imatchulidwa malinga ndi beamwidth, sidelobe levels, ndi pattern pattern.
Kukambirana komwe kwatchulidwa pamwambapa kukuganiza kuti miyeso ya netiweki yolumikizira (transformer, counterpoise, ndi zina zotero) ndi/kapena antenna sizisintha mwanjira iliyonse pamene ma frequency akusintha. Ngati miyeso yofunika ya antenna ndi/kapena netiweki yolumikizira ingasinthidwe bwino pamene ma frequency akusintha, bandwidth ya antenna ya narrowband ingakulitsidwe. Ngakhale kuti izi si ntchito yophweka nthawi zambiri, pali mapulogalamu omwe angatheke. Chitsanzo chofala kwambiri ndi antenna ya wailesi mu wailesi yagalimoto, yomwe nthawi zambiri imakhala ndi kutalika kosinthika komwe kungagwiritsidwe ntchito kukonza antenna kuti ilandire bwino.
Kuti mudziwe zambiri zokhudza ma antenna, chonde pitani ku:
Nthawi yotumizira: Julayi-12-2024
