Active antenna 10khz - 30Mhz 

"Radio Corner"  di R.Chirio

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Active Antenna, compact and small size for receiving signals in the HF Band and also for lower frequencies up to 10 kHz.The type of operation is that capacitive electrostatic antenna. The two Armors are represented by the receiving plate positioned on the base provided, while the second plate is represented by grounding. The reception sensitivity is given by the distance between the active and the earth plate. Moving away from the ground improves the input signal as well as the bandwidth down. Positioned on a pole 3-4 metres from the ground plane can give significant results with good reception signal.The MiniWhip is available on PCB circuit simple, compact design for use on the scanner and the last for base unit pole mounting. 



SMD version PCB Board + 9V battery connector and BNC socket

  August November 2013



Electric diagram


- This is SMD amplifier circuit with minimal dimensions. 14x34mm measure.

- Were kept conventional transistors: 2N3819 and 2N2222A.

- SMD Strip mounted on the antenna plate, complete with BNC connector (female) and 9V battery socket.

- Total size 40 x 110 mm, 40 x 70 mm sensitive surface

- Resistors and capacitors 1206 size.

- The battery terminals are soldered directly onto SMD capacitor to minimize the noise.


 Technical characteristics

- With 9V battery the absorption is 4mA. With 12V about 6mA.

- Bandwidth from 10 kHz to 30 MHz (-30dB),-80dB it still receives up to 150 MHz

- Output Impedance of 200 ohms is suitable for all receiver inputs.


Signal present on the Chirio Mini Whip, you see all frequencies from 0 to 20 MHz. The signal is stronger and leaving many broadcasters do not listen with a conventional wired antenna. Very present all signals up to a few tens of Khz. The antenna was mounted outside the House on a PVC pole from 3 Mt. 

mini_whip_008.jpg (55807 byte)




Tube 20 mm version for PVC pole 30 mm suitable for pole external installation.


January 2014

- In this latest version, the circuit amplifier and receiver plate, are contained within the 20 mm pipe. The whole thing is completely closed and sealed with resin to withstand inclement weather.

- Should be placed at 2-4 meters high, 30 mm PVC pipe for electrical use. Possibly use nylon cable clamp 3 upwind.

- The group is fully sealed, vent moisture takes place down through the cable passage.With shielded cable 4 x 0, 22mmq suitable for lengths of up to 6 metres of cable.

- Or on request with RG58/U cable signal drop and separate power supply with multiple shielded, this solution best suited to reach up to 30 meters of cable.

- Always presents a great sensitivity on all frequencies from 30 Mhz 0.15, improved low-range of the LW and MW.

- Are easily listenable average and strong signals up to 150 MHz.

- Power supply is recommended with 12V battery, typically with a 12V 7Ah you have over 1 month of battery life. Or via the  cable you can bring inside home, always use only 9-12V battery, any power supply introduces noise.



- This is the performance of the external antenna, a 12V battery-powered, the spectrum represents all frequencies from 10 kHz to 20 MHz, each horizontal Division represents 2 MHz, while the vertical divisions represent the intensity of signals, we note a marked improvement over the entire range received also the improvement is more pronounced for frequencies below the 2000khz.

- The reception was done at 22:00 and you can see clearly all the ranges below 20 MHz shortwave SW and their intensity.

- From 100 kHz to 2 Mhz MW and LW received with an excellent signal.

- From 2 to 5 MHz tropical bands-Most other peaks represent the bands of 49 metres, 41 metres long, 31 metres, 25 meters 22 meters 19, m. The last two smaller peaks represent the bands of 16 and 15 yards.

- Not represented by the spectre can still hear well the bands of 21Mhz, 25 Mhz, 27 Mhz CB band and 28 Mhz amateur radio. (All bands more suitable to be heard during the day)


- You see the shielded cable connection 

4 x 0,22mmq.


- White cable negative (-)

- Red cable: positive (+) 

- yellow cable:  signal output

- Green Cable:  NC 

- Common screen with negative and signal shielding

 Test on Communications Receiver ICOM IC-R20


Ascolta la ricezione in banda 40 metri LSB a 7.075 Mhz, vari OM si parlano tra loro da diverse località del Nord Italia.

- Audio files (Wav) recorded directly with ICOM IC-R20 at the October 19, 2013 15:10. Excellent reception in the 40 metre Band 7,075 Mhz from various locations in Northern Italy, Chirio Mini Whip antenna 20 mm, 12V power supply.


Here's how the Mini Whip is provided for outdoor use, 5mt cable shielded version, RG174 cable output SMA connector BNC female adapter. Bipolar power 0.25 mm2 cable.

Antenna group for PVC pole-mount 30 mm dia. antenna 20 mm length 140 mm





BNC connector SMD version for Communications Receiver ICOM IC-R20 


March 2014


- This version is designed to apply the Mini Whip directly to the BNC connector of the ICOM IC-R20, okay anyway with all scanners and receivers for HF-band type ICOM, ALINCO, YAESU, KENWOOD, YUPITERU ....

- The circuit is modified to reduce noise and was reduced to fit on half-body antenna.

-The sturdy brass tube and good quality BNC connector, allow to handle safely the scanner, holding the battery.

- Low signal lead the GAIN of the ICOM IC-R20 until MAX value

- Very good Listening on all HF. Particularly for Longwave and Medium Waves even during daylight hours.

- The receiving party is protected from static discharges as it was placed inside the insulated pipe, as is already the case for the Mini Whip XP for the base unit.

– With this version, you do not need to connect a cable to the ground with the metal part of the BNC. It is sufficient to hold the scanner to get good receptions.

Chirio Mini Whip 2014 scanner version


  See the technical characteristics of the Communications Receiver ICOM IC-R20:


Video: listening tests with ICOM IC-R5 

 VIDEO AVI  Prova di ascolto con ICOM IC-R5 con antenna Chirio Mini Whip 9V battery

( Video Avi 40MB )



 How to give new life to leave radio in the drawer ...

- Many economic radio despite having short-wave bands don't have the external antenna input, but only the stylus.


- With the Chirio Mini Whip positioned on the roof connetted with RG-58 cable then is connected to a crocodile and the antenna is connected to the stylus, shield must be connected to an aluminum or copper plate in the size 20 x 30, which will be the basis for the radio.If you can connect the radio to the negative plate with a capacitor 0.1uF, though in practice I have seen that is more than enough the ground plane.



mini_whip_018.jpg (52618 byte)

Sony ICF SW40


- The signal sometimes is quite strong that tends to saturate the input, using the DX/Local switch you can return to normal values, excellent listening CW to 7.020Mhz, fine tune in steps of 1 kHz helps achieve good stations.

- Good reception of 7 and 14 MHz bands feels the lack of conversion SSB.

- Broadcasting stations are received well on all bands, unfortunately the Mediumwave (MW) have ferrite antenna inside and cannot benefit from the good external signal ...


mini_whip_017.jpg (57699 byte)

Sony ICF 4900

- The strongest stations tend to saturate the input, using the DX/Local switch it improves reception.

- Excellent radio 80 years with manual tuning, good reception on all bands, bad for mediumwave (MW) antenna not connected.


mini_whip_019.jpg (49733 byte)

Silver Crest SWE100 B1

- This little radio 9.9 euro cost surprises for the excellent sound quality, and the 6 SW bands allow a good reception of short-wave stations.

- Unfortunately the tune is not accurate, does not allow a precise centring of the Broadcasting stations ....



 Tips for mounting antenna:
- Place the antenna on top, minimum 3-4 meters away from cables and electrical sources, the cable RG58 is good, also for lengths of 15mt.

- Increasing distance from ground it improves the signal. Usually a height of 10-12 meters from an increase of +10dB compared to 2 meters height.

- There are no major differences using a pole in iron or plastic, as the coaxial cable down from the same characteristics of a metal pole ...

- Important to have a good ground connection.

- Outside, excellent results also holding the antenna and scan, from the picture you can see the full scale signal by frequency of 160khz. Icom IC-R5




About shortwave a tuned antenna and definitely has a more centered but want to put the cost and size.

We are talking about a small antenna that I put inside a plastic tube and my son uses with the scanner to listen to the Chinese and English stations ..... 

Lets you listen to during the day, a 50-100 broadcast to full scale between 100khz and 30 MHz while in the evening/night more than 500 broadcasters from around the world ...!!!

This solution gives the possibility to thousands of fans to receive weak signals without mount roof truss, or rather make a hike in the mountains and listen to radio amateurs and issuers maybe from New Zealand .... 

Chinese radiostations are increasing the power of issuing about shortwave to bring news throughout the world, a good compact antenna completes the sistem ...


 Listening tips: stations, timetables, frequenciesand seasons

- Radioascolto, BCL, SWL e tutto quanto attorno

- Associazione Italiana Radioascolto

- International Shortwave Broadcast Bands



- Manuali e schemi per radioamatori, CB e BCL



© Roberto Chirio: all rights reserved.