Electronics > RF, Microwave, Ham Radio

How is inside a helicoidal ham-radio antenna in rubber ?

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1enry1:
in the  ham-radio dualbander handy  like  Kenwood TH-79 or th-f7 ect....

used a dual band  144 - 430 Mhz helix inside the rubber antenna, where is project and function in the two bands ?

thanks, best 73

Paul Rose:
Not sure if I fully understand the question.

What makes the helix a dual band antenna, or how well do these work on each band?

I found the following:  http://herwig.mobimail.de/2m-en.htm   which shows that they typically don't perform very well, especially not on both bands.

1enry1:
thanks !

both...my question on this rubber antenna on handy , is :

1)  where is inside ? and how is the tecnical and  RF sulution to work it ?

2)  in how mode function in 144 and in 430 mhz ?

best 73

WA5PSA:
Are you asking how it switches from one band to another? If so...there is no switching. If you transmit on 144, then the 2meter section will present the best impedence match to the transmitter, and the RF energy will simply follow that route.

Sent from my SM-N910V using Tapatalk

Chalcogenide:
Here is an explaination in Italian, as obviously 1enry1's is not a native English speaker:

L'antenna è semplicemente fatta in modo tale per cui l'impedenza è "decentemente" adattata in entrambe le bande. Non c'è nessuno switch, nessuna parte attiva, e nessuna diversa modalità di funzionamento. Per questo, le antenne bibanda tipicamente sono peggiori di un'antenna monobanda (che invece è quasi perfettamente adattata nella banda di funzionamento).

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