Ko te whakarerekētanga ā-wāhanga he ara iahiko e whakahaerehia ana te ā-wāhanga o te ngaru kawe e te tohu whakarerekētanga. E rua ngā momo whakarerekētanga ā-wāhanga ngaru sine: te whakarerekētanga ā-wāhanga tika me te whakarerekētanga ā-wāhanga korekore. Ko te kaupapa o te whakarerekētanga ā-wāhanga tika ko te whakamahi i te tohu whakarerekētanga hei whakarerekē tika i ngā tawhā o te koropiko whakakorikori, kia puta ai te nekehanga ā-wāhanga o te tohu kawe mā roto i te koropiko whakakorikori, ā, kia hanga he ngaru whakarerekētanga ā-wāhanga; Ko te tikanga whakarerekētanga ā-wāhanga korekore ka whakarerekē tuatahi i te kaha o te ngaru whakarerekētia, kātahi ka huri i te huringa kaha ki te huringa ā-wāhanga, kia tutuki ai te whakarerekētanga ā-wāhanga. I hangaia tēnei tikanga e Armstrong i te tau 1933, e kiia nei ko te tikanga whakarerekētanga Armstrong.
Ko te nekehanga ā-wāhanga ngaruiti e whakahaeretia ana e te hiko he whatunga tauranga-rua e whakamahia ana hei whakarato i te rerekētanga ā-wāhanga i waenga i ngā tohu putanga me ngā tohu tāuru ka taea te whakahaere e te tohu whakahaere (ko te tikanga he ngaohiko whakahāngai DC). Ka taea e te nui o te nekehanga ā-wāhanga te rerekē tonu me te tohu whakahaere, i te uara motuhake kua whakaritea. Ka kiia ēnei ko ngā nekehanga ā-wāhanga anaro me ngā nekehanga ā-wāhanga matihiko. Ko te whakarerekē ā-wāhanga he whakarerekētanga kī nekehanga ā-wāhanga rua i roto i te pūnaha whakawhitiwhiti ngaruiti, e whakamahi ana i te ngaru tapawhā tonu hei whakarerekē i te tohu kawe. Ka taea te wehewehe i te whakarerekētanga ā-wāhanga ngaru sine ki te whakarerekētanga ā-wāhanga tika me te whakarerekētanga ā-wāhanga korekore. Mā te whakamahi i te whanaungatanga e whakauru ana te koki kaha ngaru sine ki te auau inamata, ka taea te huri i te ngaru whakarerekētanga auau ki te ngaru whakarerekētanga ā-wāhanga (te ritenga kē rānei). Ko te ara iahiko whakarerekē ā-wāhanga tika e whakamahia whānuitia ana ko te whakarerekētanga ā-wāhanga diode varactor. He uaua ake te ara iahiko whakarerekētanga ā-wāhanga korekore i te ara iahiko whakarerekētanga ā-wāhanga tika. Ko tōna kaupapa matua ko te nekehia o tētahi ara o te tohu kawe e te whakarerekētanga ā-wāhanga 90° ka tomo ki te whakarerekētanga-kaha taurite hei pehi i te whakarerekētanga kaha o te kawe. I muri i te whakaiti tika, ka tāpirihia te tohu i whiwhi ki tētahi atu ara o te kaikawe hei whakaputa i te tohu whakarerekē-kaha. Ko te āhua o tēnei ara iahiko he pumau auau teitei, engari kaua e nui rawa te nekehanga ā-wāhanga (i raro iho i te 15°) me te hē nui rānei. He maha ngā wā ka whakamahia te whakarerekē ā-wāhanga māmā i roto i ngā tuku whakawhiti FM.
