Errante's 225 Ohm multiband HF antenna system © 2009 Francesco Errante

Unlocking the full multiband potential of the 225 Ohm elementary radiator in a folded monopole, dipole-like or turnstile layout.

All the I.T.U. amateur radio bands from the 80 m. to the 10 m. band and much more in between, in 16 ample segments.

NB. In order to avoid misunderstandings, it must be noted that this design has nothing to do with the electrically short (<< ¼ lambda) folded monopole, also generically known in this trade as "folded unipole" which is an inherentely lossy and very low impedance radiator.

Errante's 2x225 Ohm virtual ground balun for the dipole-like center-fed folded monopoles multiband HF antenna system.
Notice the two pivoting UV resistant Nylon insulators - each of them 42 cm long - which make easy the anchoring of 2 folded monopoles on each side of the balun. This is an ideal solution to install all the dipole branches with any angle from about 120 degree to 180 and upwards again to the 120 degree. From inverted "Vee" to open dipole and up to a "V".
The insulators are free to rotate around their axis, being the M8 studs which also act as the balun's electrical terminals.
The insulators and the eyelet terminals are tightened independently from each other.

The multiband radio-electric transducer system disclosed hereby is based upon the natural harmonic resonance, a very well known physics phenomenon. This system, therefore, does not utilize traps or loading coils or other artifacts for band segmentation.

This radiator acts, band by band, as a mono-band full-size aerial by resonating on a different fraction or a multiple of the relevant signal wavelength, starting from 3/4 a wavelength at each set lowest operating band.

By virtue of this radiator design, it possible to get several, well distinct, sets of bands, each set giving 8 bands in the spectrum of the HF, each and all of them yelding a COMMON IMPEDANCE VALUE of 225 Ohm. This particular common impedance value is the key factor in this system design, while Radiondistics' own patented virtual ground broadband impedance coupling and phasing network technology has allowed this system to work seamlessly with an exceptional impedance matching throughout all its frequency ranges. NO additional A.T.U. (antenna tuning unit) is needed and all its operating bands offer a generous width as this is an high impedance antenna system.

Moreover, this system requires only a reasonable amount of space to be deployed, it is easy to install and does not require tedious adjustment of the length of its radiators, as all of its bands are well defined but NOT critical. If necessary, the radiator can even be bent along its axis (this will definitely affect its radiation pattern but not its original tuning) or installed as a top fed sloper or as a center-fed inverted-vee with any angle with respect to the ground. It also requires very little room clearance from the ground or any other surrounding obstacles. Thanks to the Radiondistics' proprietary RF feeding system, no de-tuning takes place on the aerials unless they are almost right down onto the ground. For example, a 225 Ohm folded monopole arrangement, for all the I.T.U. amateur radio bands, from the 80 meter to the 10 meter, plus a lot more in between, would take about 26.5 meters of space on a streight line, while a center-fed dipole-like arrangement would need just twice as much.

Accordingly, a range of feeding systems have been deviced for:

folded monopole antennas with Errante's capacitive earth grounding ;

center-fed dipole-like antennas. See Errante's 50/225+225 Ohm balun ;

folded monopole antennas with Errante's virtual grounding ;

folded monopoles in a turnstile antenna configuration.