The article explains 7 types of useful antenna circuits which can be applied in various wireless broadcast devices.
Dual-Band Loop Antenna For 80 And 160 m Circuit
This antenna circuit may help to lessen power line noise‘ A plastic “hula hoop” or conduit 3 feet in diameter, coated along with aluminum foil like a shield can be used for L1 and L2.
![](https://makingcircuits.com/wp-content/uploads/2020/07/fig1-65.jpg)
![](https://makingcircuits.com/wp-content/uploads/2020/07/fig2-4.jpg)
L1 is two turns and L2 is one turn, threaded with the loop. S1 chooses 160- or 80-m procedure. Q1 and Q2 are configured as a preamplifier for the loop antenna. Will not transmit with this particular antenna—it is made for receiving only.
VLF/VHF Wideband Low-Noise Active Antenna Circuit
A 30- to 50-cm Whip antenna supplies reception through 10 kHz to around 220 MHZ. T1, a double gate MOSFET, delivers lower sound, high-input impedance, and high gain.
![](https://makingcircuits.com/wp-content/uploads/2020/07/fig1-66.jpg)
The circuit is powered by way of the coaxial cable employed to hook up the antenna to a receiver.
VLF 60-kHz Antenna/Preamp
Appropriate for 60-kHz common frequency reception, listed here is a schematic for any FET preamp and antenna.
![](https://makingcircuits.com/wp-content/uploads/2020/07/fig1-67.jpg)
Wideband Antenna Preamplifier Circuit
This wideband antenna preamplifier features a gain of about 20 dB via 40 to 860 MHZ, covering the complete VHF, FM, commercial, and UHF bands.
![](https://makingcircuits.com/wp-content/uploads/2020/07/fig1-68.jpg)
![](https://makingcircuits.com/wp-content/uploads/2020/07/fig2-5.jpg)
A phantom power supply delivers dc towards the pre amp through the coaxial cable feeding the unit.
HF Broadband Antenna Preamp Circuit
The HF/SW receiver preamplifier is consists of a broadband toroidal transformer (L1~a and L1-b), LC network (made up of a 1600-kHz, high-pass filter and a 32-MHZ, low-pass filter), L2 and L3 (26 turns of #26 enameled wire wound on an Amidon Associates T-50-2, red, toroidal core), a couple of resistive attenuators (ATTN1 and ATTN2), and a MAR-X device.
![](https://makingcircuits.com/wp-content/uploads/2020/07/fig1-69.jpg)
Demonstrated in this article could be the composition of a simple 1-dB pi-network resistor antenuator. This is actually the technique of supplying dc power to a preamplifier employing simply the RF coax cable.
Simple Balun Circuit
An good old ferrite rod from your junked radio receiver could be applied to build an antenna balun as demonstrated.
![](https://makingcircuits.com/wp-content/uploads/2020/07/fig1-70.jpg)
![](https://makingcircuits.com/wp-content/uploads/2020/07/fig2-6.jpg)
![](https://makingcircuits.com/wp-content/uploads/2020/07/fig3.png)
Loop Antenna Preamplifier Circuit
This preamplifier features a internal regeneration control boost gain selectivity. C1 is a solitary or multi gang AM broadcast band tuning capacitor. L1 is a ferrite loop antenna, tapped at approximately 15 to 25% of overall turns.
![](https://makingcircuits.com/wp-content/uploads/2020/07/fig1-71.jpg)
This circuit can prove great for low frequency (up to 3 MHZ) reception, in which a loop could be beneficial to minimize external noise pickup,
Leave a Reply