wide band (DX) receiving antenna.
This is a vastly improved version of the pa0rdt
"Miniwhip" active receiving antenna.
Preliminary development data.
The use, copy and modification of all info on this site
is only permitted for non-commercial purposes, and
thereby explicitly mentioning my radio amateur call sign "PA0NHC"
as the original writer / designer / photographer / publisher.
of 2 PCBs, and needed transistors, are available.
You need a clean,
12V to 14V, 120mA external power supply.
A design for a little, noise- and rattle free power supply, is
Miniwhip antenna PCB glued in end cap,
ferrite choke (2x5 t - 1/10" coax) and red grounding wire, 25cm x 50mm PVC
pipe, end cap.
Download the PDF parts list 20170909 HERE.
does not work ? Press F5 and try again.
See also the bottom of this page for important installation
Location of C14
MODs for PCB #13 :
NOT be placed.
C14 must be soldered onto the
PCB bottom surface, see photo ==>>
For best VLF reception : C4,7=0.47uF film, L2,3=1mH (Low Ri).
For best reception below 30kHz : enlarge the antenna source capacitance by using
- Fully class A circuitry, clean reception without
- New version 13, improved
circuitry for T1
- Only 0.6dB insertion loss, for higher sensitivity.
- PCBs with enlarged SMD solder pads for easier heating and solder flow.
- Now using commonly
available new type very hi-Ft UHF
transistor for T2.
- Biggest strong signal handling, max output 2Vrms (!).
- All commonly available parts, only two SMD components.
- The cleanest reception possible if well
- Really wideband with R/C coupling to the receiver, no
which signals is the Miniwhip useable ?
The Miniwhip is a vertical positioned antenna. The following properties are
valid for all vertical antennas :
- Good results for the reception of VLF / LF / LW / MW / SW short distance ground
- Good results for the reception of SW signals at distances over 300km
The Miniwhip is (like all vertical
antennas) NOT suitable for NVIS, that is for the reception of
signals of distances UNDER 300km between 3.5MHz and 7.2 MHz..
Listen DX at :
The broad band
webSDR at the university Twente (50kHz to 30MHz).
They use a "Miniwhip".
Highly recommended to
Theory about the practice
of Miniwhip antenna (written by pa3FWM).
Ready to install.
Antenna PCB glued into a end cap.
Updated antenna and power circuit.
New version schematics :
1. setting optimal steepness for T1.
2. T2 now is a commonly
available modern UHF hi-Ft SMD transistor.
3. R13 is normally a wire bridge.
Exchange it for a 47 Ohms resistor,
should oscillate due to mismatch and unfavorable length of the coax cable.
4. The splitter unit is fused and zenered against damages
if a short
circuited coax cable, over voltage or wrong power polarity occurs.
Both PCBs are now double sided.
The splitter PCB is best installed into a shielding metal box.
The antenna PCB must be installed vertically, in a non-screening,
fully closed, rain resist housing.
instance a 40mm dia. gray PVC pipe, abt. 35cm long, fully closed with
top and bottom end caps.
The antenna surface
"ANT" must be FULLY ABOVE the metal mast.
The top of electronics surface (C5) should be at the same level as the
mast top, or above it.
"GND h2" must be connected to the noise free grounded mast via
a thick wire.
Highly recommended : Leave 13V power allways on. Then the internal power dissipation
(2Watts) prevents condensation.
The PCB can be :
1. Glued into top end into a PVC
end cap (see photo ==>>).
2. hanging on one (plastic) screw through h1
3. Screwed at h1 and h3 with
When placing the splitter PCB into a
metal box, use at each screw h1 and h2 two extra M3 nuts as spacers between
and the box.
For stable mechanical and grounding contact use tooth locking rings :
1. under the outside flanges of both BNC bushes, and
2. under the M3 PCB top nuts.
antenna surface (10cm upper part of the PCB) must be fully ABOVE the top
of the antenna mast.
Grounding hole h2 must be connected to the noise free
grounded antenna mast.
C10 must not be placed. In stead C14 must be soldered onto the
PCB bottom surface.
It must be connected to the hot ends of R1 and R11.
See component list.
- WARNING: carefully check the type and value of EVERY part, BEFORE
soldering. Measure resistors using a digital ohm meter.
Removing later on can be difficult.
- - Solder wire bridge R13 on the bottom plane
of the antenna PCB. Prevent a short circuit with ground. Wire ends may not
be above the top copper surface.
- - Solder all resistors.
- - Solder all ceramic capacitors.
- Solder all film capacitors and the fuse holder.
- Solder the elco's and the coils.
- Solder the BNC bus onto the antenna PCB. Check for short circuit between
R13 and ground.
- Take anti- static measures, and prevent over
heating while soldering the transistors.
Solder fast with little solder, and let cool down after every single
- - Solder on the PCB bottom surface the
MOSfet T1. REM : see the broad pin (drain). The FETs legs are bend down
towards the solder pads on the PCB.
- Solder on the PCB bottom surface the
SHF transistor T2. First solder the three small pins, and as last and fast
the broad cooling fin.
Every antenna performs as good as its installation permits it to.
- For max. sensitivity :
- this antenna should be positioned as high and free from metal conductors as possible
- the ground plane of the PCB must NOT be lower than the top of the mast
(the connecting trace between the electronics and the antenna surface, and the antenna surface itself must ALL be ABOVE the top of
- For best signal-to-noise ratio :
- install the Miniwhip onto a well grounded mast
- connect "GND" of the Miniwhip PCB (h2) to that mast
- place HI-Ui ferrite cores (Ui between 3000 and 10.000) on the beginning and end of all cables, to block cable noise currents (see below).
For best noise free reception:
The complete Miniwhip antenna+splitter+power supply may only be grounded at the antenna pole.
Disconnect the ground wires at the receiver and the 13.6V power supply.
Be sure you are protected by :
an automatic ground-current-leak-switch in the mains supply line.
Before connecting plugs, install hi-Ui ferrite material on the beginning and the end of every cable.
Wind cables several times through the ferrite hole for far more effectiveness.
3 times through the hole = 9 times more effective than 1 time straight through the
TIP : useable and cheap ferrite rings:
Conrad NR 534480 (Ui=10.000, remove the insulating shells).
Conrad NR 500683 (Ui=5000, Epcos B64290-L618-X35)
Epcos has more suited ferrite rings (ui=5000-10.000) in different dimensions.
(Earlier version antenna PCB).
Here a smple of a mantle current choke. A few windings through a HI-Ui ferrite core
(Ui=8000) will block noises coming from the coax cable.
Use thin coax with maximal number of turns through the ring core.
3 times through the hole = 9 times more effective than 1 time straight through the hole.
==>> At h2, the ground plane of the PCB, should be connected to a
noise-free grounded mast, using a thick wiret.