daim duab 1
1. Kev ua haujlwm ntawm lub nqaj
Lwm yam kev ntsuas uas siv tau rau kev ntsuam xyuas qhov zoo ntawm kev xa thiab txais cov kav hlau txais xov yog qhov ua tau zoo ntawm lub teeb. Rau lub kav hlau txais xov nrog lub lobe tseem ceeb hauv qhov kev taw qhia z-axis raws li pom hauv Daim Duab 1, qhov ua tau zoo ntawm lub teeb (BE) yog txhais tias:
Nws yog qhov sib piv ntawm lub zog xa lossis tau txais hauv lub kaum sab xis θ1 rau tag nrho lub zog xa lossis tau txais los ntawm lub kav hlau txais xov. Cov mis saum toj no tuaj yeem sau ua:
Yog tias lub kaum sab xis uas thawj qhov xoom lossis tus nqi tsawg kawg nkaus tshwm sim raug xaiv ua θ1, qhov ua tau zoo ntawm lub teeb sawv cev rau qhov sib piv ntawm lub zog hauv lub lobe tseem ceeb rau tag nrho lub zog. Hauv cov ntawv thov xws li metrology, astronomy, thiab radar, lub antenna yuav tsum muaj qhov ua tau zoo ntawm lub teeb siab heev. Feem ntau xav tau ntau dua 90%, thiab lub zog tau txais los ntawm sab lobe yuav tsum me me li sai tau.
2. Qhov Bandwidth
Qhov bandwidth ntawm lub antenna yog txhais tias yog "qhov ntau zaus uas qhov kev ua tau zoo ntawm qee yam ntxwv ntawm lub antenna ua tau raws li cov qauv tshwj xeeb". Qhov bandwidth tuaj yeem suav hais tias yog qhov ntau zaus ntawm ob sab ntawm qhov nruab nrab zaus (feem ntau xa mus rau qhov zaus resonant) qhov twg cov yam ntxwv ntawm lub antenna (xws li input impedance, directional pattern, beamwidth, polarization, sidelobe level, gain, beam pointing, radiation efficiency) nyob hauv qhov ntau uas lees txais tau tom qab sib piv tus nqi ntawm qhov nruab nrab zaus.
Rau cov kav hlau txais xov broadband, qhov bandwidth feem ntau yog qhia ua qhov piv ntawm cov zaus sab saud thiab sab qis rau kev ua haujlwm tau txais. Piv txwv li, qhov bandwidth ntawm 10: 1 txhais tau tias qhov zaus sab saud yog 10 npaug ntawm qhov zaus qis dua.
Rau cov kav hlau txais xov narrowband, qhov bandwidth yog qhia ua feem pua ntawm qhov sib txawv ntawm zaus rau tus nqi nruab nrab. Piv txwv li, 5% bandwidth txhais tau tias qhov ntau zaus uas txais tau yog 5% ntawm qhov zaus nruab nrab.
Vim tias cov yam ntxwv ntawm lub kav hlau txais xov (input impedance, directional pattern, gain, polarization, thiab lwm yam) sib txawv nrog zaus, cov yam ntxwv bandwidth tsis yog tshwj xeeb. Feem ntau cov kev hloov pauv hauv cov qauv directional thiab input impedance sib txawv. Yog li ntawd, qhov directional pattern bandwidth thiab impedance bandwidth yog qhov xav tau los hais txog qhov sib txawv no. Qhov directional pattern bandwidth muaj feem cuam tshuam nrog qhov nce, sidelobe level, beamwidth, polarization thiab beam direction, thaum qhov input impedance thiab radiation efficiency muaj feem cuam tshuam nrog impedance bandwidth. Bandwidth feem ntau yog hais txog beamwidth, sidelobe levels, thiab cov yam ntxwv ntawm cov qauv.
Cov lus sib tham saum toj no xav tias qhov ntev ntawm lub network txuas (transformer, counterpoise, thiab lwm yam) thiab / lossis antenna tsis hloov pauv li cas thaum lub zaus hloov pauv. Yog tias qhov ntev tseem ceeb ntawm lub antenna thiab / lossis lub network txuas tuaj yeem hloov kho kom raug thaum lub zaus hloov pauv, qhov bandwidth ntawm lub antenna nqaim tuaj yeem nce ntxiv. Txawm hais tias qhov no tsis yog ib txoj haujlwm yooj yim feem ntau, muaj cov ntawv thov uas nws ua tiav tau. Piv txwv li feem ntau yog lub xov tooj cua antenna hauv xov tooj cua tsheb, uas feem ntau muaj qhov ntev hloov kho tau uas tuaj yeem siv los kho lub antenna kom tau txais kev txais tos zoo dua.
Yog xav paub ntxiv txog antennas, thov mus saib:
Lub sijhawm tshaj tawm: Lub Xya Hli-12-2024
