Miniwhip

Pa0nhc improved version of pa0rdt "Miniwhip" active wideband receiving antenna.
Update : 20200828
(C) The use, copy and modification of all info on this site is permitted, but only for non-commercial purposes, and
thereby explicitly stating my radio amateur call sign "PA0NHC" as the original writer / designer / photographer / publisher.

Youtube video presentations :
English version

To prevent un-authorized commercial copies, NO component details are given in the schematic diagrams below.
No Gerber nor PNG PCB files will be provided.
All copies sold at other sites, which refer to my call, and for details to my internet site, are illegal.

Installing parts should be easy for experienced builders.
Both parts lists will coincide with the white PCB topsilk imprints and part placement drawings.
Construction details, test data and de-noising instructions are given in the downloadable texts.

Bandwidth : 5kHz to 148MHz +0/-3dB.
Sensitivity :
- Using the internal antenna surface only : abt. -17dB.
- With added external 1,5m x 1cm antenna rod : abt. -12dB.
Input RF impedance abt. 7 Mohm // 6pF.
Input DC resistance 22 Mohm.
Includes over-voltage protection.
Output impedance : 50 Ohms asymmetrical.

This version Miniwhip :
Is an excellent DX antenna for vertically polarized wide band reception of :
VLF,LW,MW,SW,FM broadcast, airplane band and 2m amateur band.

However : => Between 1.8MHz and 7MHz, the reception of regional signals (20-400km range) will be weaker. <==
The Miniwhip is NOT an NVIS antenna (like every vertically polarized antenna).

IMPORTANT :
Every active receiving antenna needs careful de-noising measures.
E-field antennas (like this Miniwhip) also must be connected to a dedicated noise free ground.

LATEST UPDATES.
20200828
Antenna unit.
Common mode choke L5 :
a. For best results ONLY use #31 ferrite (high loss Ui=1500).
202008 : FairRite item 26 31 80 12 02 is temporarily unavailable.

Better (longer) replacements :
FairRite 26 31 10 19 02
or
FairRite 26 31 10 20 02

Wind until the core hole is filled.
Every turn must lay beside the former as shown below.
Do NOT cross another turn.

Best choke :
Picture 1 : two firmly twisted, or fully paralleled, lacquered wires 0.5mm.
This will have a characteristic impedance of 50 Ohms AND the largest choking impedance.
OR
One twisted wire pair retrieved from an UTP cable.
Its wire pair impedance is 100 Ohms, but due to the short wire length compared with the wavelength,
mismatch to 50 Ohms is mostly negligible.

Picture 2 : THIN coax, RG178 or RG316

Check the insulation between :
wire to wire
and
wires to the core.

--------------------------

Splitter unit.
b. Insert an extra choke between the PWR+ connection on the PCB, and the power+ connection on the PWR-bus.
Choke construction :
Wind as much as possible turns thin (0.25-0.5mm lacquered wire) in the hole of a :
small FairRite #75 core 26 75 62 64 02 (high Ui=5000) better in VLF
OR
small FairRite #31 core 26 31 48 01 02 (high loss Ui=1500) more wide band.
Check the insulation between :
wire to wire
and
wires to the core.

c. Do NOT connect the PWR-minus point at the PCB.
The PCB mass planes must electrically only be connected to the INSIDE of the splitter box through the 3mm screws.

d. The power bus and BNC buses MUST all be fully metal
and
installed in perfect electrical contact with the OUTside of the box.

e. Use CMC's on all cables (see de-noising)

f. GROUND the antenna PCB, nothing else..

Unique pa0nhc antenna input circuit for highest IMD-free output, widest bandwidth,
and a wideband output circuit including an effective common mode choke.

Measured frequency characteristics.

50kHz - 30 MHz.
The -2 dB dip at 15 MHz is a weak choke resonance in the splitter.
Orange = nanoVNA Ch0 reflection damping
(70cm coax, 50 Ohm // 3p5 coupling).

50 kHz to 200 MHz, -3 dB @ 147 MHz.