GOOD­BYE, YAGI

South Africans in­vent the first new TV an­tenna in decades and usher in a new era of dig­i­tal re­cep­tion.

Popular Mechanics (South Africa) - - How Your World Works -

HIDETSUGU YAGI’S EN­DUR­ING AN­TENNA DE­SIGN has lasted more than nine decades on rooftops from Sand­ton to Chicago. Yet it might not make its 100th birth­day, thanks to three South African in­ven­tors.

De­signed to help South Africans – par­tic­u­larly low-in­come house­holds – make the tran­si­tion from ana­logue to dig­i­tal TV broad­casts, the rad­i­cally new fold­able an­tenna is called Di­giant. Its name re­flects both its pur­pose (“dig­i­tal an­tenna”) and its in­sect-like struc­ture.

Co-in­ven­tors Dr André Fourie (ex­ec­u­tive chair­man and founder of Poynt­ing An­ten­nas), Dr Derek Nitch (Poynt­ing's chief tech­ni­cal of­ficer) and Ed­uard Walker, CEO of an­tenna-man­u­fac­turer TEMIC, spent the bet­ter part of a year dis­sect­ing, ex­trud­ing, de­sign­ing, cut­ting and test­ing de­signs to cre­ate a ro­bust and af­ford­able de­sign. But in the age of satel­lite dishes, why do we even need a new an­tenna de­sign?

Be­cause, de­spite the growth of satel­lite TV broad­casts, dig­i­tal ter­res­trial TV re­mains the most used way of broad­cast­ing TV, es­pe­cially free-to-air and pub­lic broad­cast­ing TV. In South Africa, the need for an af­ford­able dig­i­tal TV an­tenna is even more pro­nounced. We're late to dig­i­tal mi­gra­tion – and mean­while, the In­ter­na­tional Tele­com Union (ITU) has al­ready set aside the tra­di­tional ana­logue broad­cast­ing range for the ex­pan­sion of other com­mu­ni­ca­tion ser­vices. Those ser­vices in­clude ad­vanced mo­bile and com­mer­cial wire­less broad­band.

Dig­i­tal mi­gra­tion, be­sides bring­ing high-def TV to all South Africans, will also free up some TV fre­quen­cies (the dig­i­tal div­i­dend) for 4G/LTE high-speed In­ter­net. Ex­pect dra­mat­i­cally faster cel­lu­lar In­ter­net speeds.

The Di­giant works in a 470 – 862 MHZ fre­quency band. It con­nects to a set-top box that de­codes the sig­nal for use by any tele­vi­sion. In the process, it frees up the tradi- tional TV broad­cast spec­trum, while al­low­ing more TV chan­nels on the new, nar­rower, dig­i­tal TV fre­quency.

The Di­giant's de­sign is a rad­i­cal evo­lu­tion from a Vi­valdi horn-type an­tenna. The in­ven­tors sim­pli­fied this to the six-legged “skele­tal” struc­ture so that it traces only the min­i­mal out­line of the much more solid plate struc­ture of the Vi­valdi. This vastly sim­pli­fied struc­ture was de­signed to be mass-pro­duced us­ing ad­vanced alu­minium die cast­ing. Each leg is hinged in the mid­dle, al­low­ing the an­tenna to be folded um­brella-style and shipped in a box ten times smaller than usual.

But be­ing small and fold­able cer­tainly doesn't de­crease per­for­mance. Apart from its strong re­cep­tion ca­pa­bil­ity, the Di­giant has been tested to with­stand winds of up to 160 km/h and tem­per­a­tures rang­ing from -20 to +70°.

The first of 500 000 units or­dered by the gov­ern­ment were shipped to bor­der towns in the North­ern Cape, al­low­ing ana­logue broad­casts to be switched off there first and pre­vent­ing the ana­logue TV sig­nals from bleed­ing across the bor­der and in­ter­fer­ing with our neigh­bours' broad­cast spec­trum.

With the first ship­ments un­der way, pro­duc­tion is be­ing ramped up to meet the tar­get of 5 mil­lion low-in­come house­holds across South Africa, a tar­get set by the gov­ern­ment. But the man­u­fac­tur­ers are think­ing big­ger. “The Di­giant has been awarded patent rights in over 30 coun­tries,” says Fourie. “We are in­ves­ti­gat­ing li­censed man­u­fac­tur­ing in sev­eral coun­tries that re­quire a low-cost, high-per­for­mance dig­i­tal TV an­tenna.” PM

Top: The first of 500 000 units or­dered by the gov­ern­ment were shipped to bor­der towns in the North­ern Cape. Above and right: In pro­duc­tion the "ant"- like look be­comes ap­par­ent.

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