Subscribe free newsletter to get latest products and discount information. Alignsat can supply satellite receive only antenna ,and can receive TV signal, Alignsat RXO antenna is made of high accuracy stretch-formed aluminum m receive antenna with stable structure. Write a review on this product! 22341292 requests since 12 июля 2005 г. Over the past several years I’ve been asked one question. Are you still building the receive loop antennas ?
It is hard to believe twenty years have gone by, but to answer the question. W7AE built the first loop for 160m following plans laid out in the ARRL Antenna Handbook. Encouraged by the results I built one for 80m. I found that with a proper pre-amp, such the Palomar series, or Ameco’s PT-3 there was a significant lowering of noise, but the signals that I was unable to hear on my sloper now were quite workable using the receiving loop. For the past several years, we experimented with several different configurations , including a circular, and square loop.
Click Here If you want me to construct one for you. Click here If you wish to build one yourself. A Wide Bandwidth Active Loop Receiving Antenna. A versatile wide bandwidth receiving antenna suitable for general short-wave amateur band reception. The loop amplifiers “power down the coax” schematic. Possible improvements and things to try. LF, MF and lower HF bands have now become swamped with local QRM.
Receiving weak signals or having QSO’s became very difficult. While they possessed the wide bandwidth capability desired they offered little or no improvement in signal-to-noise ratio. In all cases the antennas had been located outside some 20 Metres away from the house as far away as possible from local noise sources. I was particularly impressed by the stability of Johns amplifier design regardless of the construction methods used. Initial daytime tests with a 1 Metre diameter loop proved the loops ability to receive signals over several octaves and with much reduced local QRM levels. Minor modifications have been made to John’s original design to protect the loop amplifier when used in conjunction with a transmitter and to improve the strong signal handling capability. The construction of the amplifier does not appear to be very critical and four versions have been successfully built using various methods of construction.
Tuning from time to time, there is absolutely no reason why you cannot get rid of cable today! Directed waves form the familiar standing waves most often considered for practical antenna, what are good mathematical models for spider webs? An antenna is the interface between radio waves propagating through space and electric currents moving in metal conductors, so the same effect occurs for reception of radio waves. When the resulting current reaches the end of the conductor, you can create your own horizontal piece by using a piece of the 300 ohm cable. For a terrestrial antenna, designs about on the net.
The first used breadboard construction, the second and third built over a ground plane while the current version is built on a scrap of strip board. The relay has normally open contacts which close when the amplifier is powered up for receiving and open when the power is removed for transmitting or when the loop is not in use. The relay type is not critical though it should have low contact resistance. While nothing can protect the antenna from a direct lightening strike the open relay contacts do offer some protection from surges caused by nearby thunderstorms. The loop also has a gas discharge device connected across its terminals providing a second line of defence against surges. Because most of the local QRM is thought to be due to conducted and radiated emissions from the mains wiring it was decided to place the antenna outside at the bottom of the garden as far away from the local noise sources as possible. 12 Volts DC supply from the shack to power the loop amplifier.
If such a failure should occur then L2 would provide a low resistance path for the D. In normal operation the inductive reactance of L2 is high enough such that it will not effect the passage of R. D is also fitted to the enclosure to confirm the power is present. The loop amplifier circuit diagram is shown below. The loop amplifier “power down the coax” circuit is shown below. Some images of the loop antenna and loop amplifier are shown below.
Click on any of the thumbnail images for a higher resolution picture. Using a pair of matched devices may also give improved performance by virtue of the reduced distortion. Using devices capable of higher collector dissipation it should be possible to increase the standing current and further improve large signal handling capability. During the testing phase it was found that a good test for overloading was to listen around 28 MHz after dark when the 10 Metre band is normally closed. Assuming you are using a receiver with good dynamic range then any trace of broadcast stations on that frequency might indicate overloading within the loop amplifier or distortion due to a pair of badly mismatched devices.