Active Wide band Loop Antenna for 10-30 MHz Band shortwave band you can construct in your home as Do It Yourself Project (Source article : Elektor Electronics Magazine).
Parts List :
PCB Design and component place :
Loop Antenna is a good indoor antenna alternative for a long wire antenna.
Active Wideband Loop Antenna for 10–30 MHz Shortwave Band – DIY Home Construction Guide
The Active Wideband Loop Antenna is one of the most effective receiving antennas for the
10–30 MHz shortwave spectrum. Unlike long wire antennas that require large outdoor space,
this compact loop antenna can be built at home as a DIY project while delivering excellent
performance for shortwave listening (SWL), amateur radio, SDR receivers, and HF monitoring.
Originally inspired by classic designs published in Elektor Electronics Magazine,
this modernized version is optimized for today’s receivers and offers
low noise, wide bandwidth, and high signal-to-noise ratio.
Why Use an Active Loop Antenna?
Traditional wire antennas often suffer from high noise pickup, especially in urban environments.
An active loop antenna solves this problem by using a small magnetic loop combined with a
low-noise RF amplifier.
- Compact size – ideal for apartments
- Excellent noise rejection
- Wide frequency coverage (10–30 MHz)
- Directional properties reduce interference
- Perfect for SDR and portable receivers
This antenna is designed primarily for receiving, not transmitting.
Frequency Coverage: 10–30 MHz Explained
The 10–30 MHz HF spectrum covers a wide range of important radio services:
- International shortwave broadcast stations
- Amateur radio bands (20m, 17m, 15m, 12m, 10m)
- Utility and maritime communications
- Military and aviation monitoring
- Time signal stations (WWV, CHU)
A wideband loop antenna allows you to monitor all these frequencies without retuning coils
or switching antennas.
How an Active Loop Antenna Works
The antenna consists of two main sections:
1. Magnetic Loop Element
A loop of wire responds primarily to the magnetic component of radio waves,
which makes it inherently resistant to electric-field noise generated by household electronics.
2. Wideband Low-Noise Amplifier
The amplifier buffers the loop, providing:
- Impedance matching
- Flat frequency response
- High dynamic range
- Low intermodulation distortion
This design ensures consistent performance across the entire 10–30 MHz range.
Advantages Over Long Wire Antennas
| Feature |
Active Loop Antenna |
Long Wire Antenna |
| Size |
Compact |
Large |
| Noise Immunity |
Excellent |
Poor |
| Urban Use |
Ideal |
Problematic |
| Bandwidth |
Wide |
Variable |
DIY Construction Overview
This project is suitable for beginners with basic soldering skills.
All components are inexpensive and widely available online.
Loop Dimensions
- Loop diameter: 0.8 – 1 meter
- Wire: insulated copper wire or coax shield
- Mounting: PVC pipe or fiberglass support
Larger loops improve sensitivity but are not mandatory.
Electronic Circuit Description
The amplifier uses a wideband RF transistor or JFET configured as a low-noise buffer.
The design prioritizes stability and flat gain across HF frequencies.
- High input impedance
- 50Ω output matching
- Powered via 9–12V DC or bias-T
The amplifier can be housed in a small waterproof enclosure near the loop.
Component List (DIY Friendly)
- Insulated copper wire (1–1.5 mm)
- Wideband RF transistor (2N5109 / J310 / BF245)
- Resistors (metal film recommended)
- Capacitors (ceramic + electrolytic)
- PCB or prototyping board
- BNC or SO-239 connector
- 9–12V DC power supply
- Plastic enclosure
🛒 Recommended Components (Affiliate Links)
Using quality components improves reliability and noise performance.
Installation Tips
- Install outdoors or near a window
- Rotate loop to null interference
- Keep amplifier close to loop
- Use quality coaxial cable
Performance Expectations
When properly built, this antenna delivers:
- Strong reception across 10–30 MHz
- Reduced urban noise
- Stable operation with SDR receivers
- Excellent DX capability
Many users report better results than long wire antennas in noisy environments.
Is This Antenna Legal?
Yes. This antenna is receive-only and does not transmit RF energy.
It complies with radio regulations worldwide.
Conclusion
The Active Wideband Loop Antenna for 10–30 MHz is one of the most practical DIY antennas
for modern shortwave listening. With compact size, low noise, and wide coverage,
it is ideal for home construction and urban environments.
Inspired by classic Elektor designs and updated for modern receivers,
this project offers excellent performance.
For you who wants to experiment with the early computer technology 8 bit Data , this project is very useful to start with, and 8 Bit Data Digital I/O still use in Industrial process , such on factories process control system.
The Design of This Digital Output card is based on accessing PC UART as shown at table2. The basic lines for UART communications is TXD and RXD for Transmit Data and Receive Data. The other lines are DTR, RTS, CTS, DCR, DCD and RI , each for input and output in communication 8 Bit Data via Serial Communication.
