1. I am designing a portable antenna with a radiating element and a balun that are not close to each other.

  2. The impedance has been designed to be close to 50 ohms.

  3. So I will feed the antenna with a twisted pair of enameled copper that should be close to 50 ohm too.

Q: I was wondering however how to expose the balanced terminals on the balun enclosure so that they should be close to each other in order not to increase impedance.

  • An obvious choice would be a 75 ohm Twinax socket and fitting the custom twisted pair to a Twinax male connector, but these connectors are expensive.

Q: Any idea of what kind of terminals I could use, with limited separation while maintaining sufficient mechanical clearance to avoid shorting the terminals?

(That's why I am reluctant to use spade connectors that could rotate inadvertently). I thought of small banana plugs or RCA connectors. Any other idea ?

  • It will handle limited power (30W max at UHF, max 400MHz)
  • $\begingroup$ i reviewed the design of the antenna to have a 100 ohm differential impedance. and since the output of the second stage of the balun is a guanella balun with a center tap the differential impedance is near 100 ohm, but the impedance to the center tap should be near 50 ohm, then i think that using two bnc sockets with the ground of each bnc connected to the center tap would give 50 ohm on each terminal relative to the center tap. then each center connector of the two coax will connect to each loop radiator leg. the coax braid will not be connected at the element side. i hope i am right. $\endgroup$
    – rodv92
    Commented Jul 24, 2019 at 10:23
  • $\begingroup$ fyi, the first stage is a trifilar unun. $\endgroup$
    – rodv92
    Commented Jul 24, 2019 at 10:24


You must log in to answer this question.

Browse other questions tagged .