That is certainly the case with the basic “loop” antenna, an often misunderstood critter, but one that gives absolutely the most for each foot of wire of any antenna I have had occasion to play with. They are long, long, long Who has room for over feet of wire in the case of a full-wavelength loop for meters? Won’t that thing become the perfect conduit right into my house for lightning and other “wrath of God” type things? And will it work on more than one band? I don’t want something that big in my yard if it only gets me a narrow swatch of one band. First, let me reassure you that such an antenna does not necessarily take much room. One reason I went to one in the first place is because I didn’t have room for a foot-long dipole for and I wanted to give the “top band” a try for the first time in my 45 years of being a ham.
Connecting an FM/AM antenna
Even though I had a working mostly homebrew station, I now realize I had only a small idea what I was doing, and almost no understanding of what made antennas work. My entry into Ham radio was from modified broadcast radios, and the very active meter mobile group in Toledo, Ohio. I always thought the longer the antenna, the better the “pickup”.
U Kiwa MW Loop $ SOLD Medium Wave Loop Antenna ( to kHz.) The Kiwa Medium Wave Loop covers kHz. rotating in azimuth and elevation.A compass is built in to the top. With Owner’s es a power adapter connected to screw terminal inputs on the back of the control box. [07/04] Click here for technical info on this discontinued model.
Thicker wire provides better reception and is more suitable for transmitting if you have a license but it is heavier. The antenna I’ve demonstrated at recent events uses 1mm thick wire. Smaller insulators are better as they are lighter and less expensive. You may want to buy more than one balun, for example, a 4: Make sure it is waterproof, has hooks for attaching a string or rope and an SO socket.
The cable must be 50 ohm. There are even lighter and cheaper alternatives if you only need to receive. A spare USB mobile phone charge plug may be suitable. A ligher and cheaper string is better for portable use while a stronger and weather-resistent rope is better for a fixed installation. For example, for a centre frequency of Add an extra 24 cm extra 12 cm on each end for folding the wire through the hooks on the balun.
AM Loop Antenna
Hence after having a good Receiver and a Transmitter or Transceiver , the next important item one should have to set up a ham radio station is a good antenna. The radio frequency power that is generated in the transmitter should be radiated in the form of electro magnetic waves. It is the job of the antenna to convert the RF power into radio waves and radiate them into the desired direction for effective communication. For this purpose, the antenna should be located well above the ground and it should be kept away from any tall buildings, trees, electrical power conductors, telephone and telegraph wires and other metal objects that will absorb the energy.
The antenna should be erected as high as possible for the best results. Antennas has reciprocity in that a good transmitting antenna will also work as a good receiving antenna.
Nov 13, · To hook up a TV antenna, start by determining if you need an indoor antenna, or a more powerful outdoor antenna by visiting a site like Once you have the right antenna, turn off and unplug your TV before connecting the antenna cable to the back of the : 1M.
The circuit is rather simple, uses only one transistor and few passive components and performs well in terms of frequency stability, almost zero drifting after about 4 hours of continuous operation. With 12 volt DC it will deliver 1 watt RF power. The most important parts of the oscillator are the transistor Q1 and the tuned circuit, which comprises the inductor Ll and the variable capacitor CV1. When the battery is first connected, a brief surge of current flows from the collector to the emitter of Q1, causing an oscillating i.
An oscillating voltage therefore appears at the junction of Ll and CV1. The frequency of the oscillation depends on the values of Ll and CV1, so that varying the value of CV1 tunes the oscillations to the exact frequency required. In order to achieve a high output level, you will need a well tuned antenna, and a large heatsink to dissipate the heat from T2 transistor. Transmitter was mounted in metal enclosure and works extremely well. Frequency adjustment is accomplished with MV varactor diode and R7 10K potentiometer.
The amplifier chip is an integrated circuit containing multiple transistor stages and all other parts conveniently within a single small package.
Crane Company One of the most useful and fun toys in my antenna arsenal is the C. Crane Twin Coil Ferrite antenna. I have used it with many radios from portables to large table tops and it has worked equally well with almost all of them. It can also make many radios far more convenient to use because of its immense adjustability and flexibility as you will see.
Kids’ Resource Center – Fun, educational projects to inspire young minds, and articles on education This is the circuit diagram of the AM radio: The antenna coil is 40 turns of thin, plastic covered hookup wire in a spiral construction used in radios of old. Short wave radio with tuned loop antenna. The short wave radio looks more like.
In the first couple hours of having it up I was able to hear stations I could not hear before. The skywire loop is an excellent antenna – they can be a bit of work to get up in the air if you have a lot of obstacles trees, xyl, etc. What’s the right length? Anything shorter becomes a challenge to match on the upper bands and increases the chances of the feedline becoming the radiator and a source of RFI. The length of a loop best suited for operation on meters is too short for use on the higher bands.
The optimal choice is to cut the loop for resonance on the highest band you plan to use, however it becomes difficult to use a giant meter loop on 10 meters – your feedline length must not be a fractional wavelength of the band you want to use or else you’ll wind up using your feedline as the radiator! I recommend a different loop for use on meters if those are your favorite bands, mostly because it’s easier to put up 71 feet of wire 14MHz with only 18 feet per side.
It’s also easier to make a 23′ diameter loop for 20 meters more circular instead of square shaped. Remember, the ideal loop is a perfect circle – it’s not too hard to make an 8-sided loop for 20 meters using PVC pipe and some dacron rope to hold it rigid. Formula for length of full wave loop The formula for a calculating the length of a full wave loop antenna is: Not an optimal length.
ANTENNAS FOR HAM TRANSMITTERS
In addition to the fact that the new antenna adds longwave capability the biggest step forward is usability…ease of use has been slightly improved, primarily because the tuning is now a little broader and therefore less critical. With the older antennas, the tuning control was SO pinpoint critical that many people mistakenly thought their units were dead because it was easy to skip right over the tuning spot without hearing even a blip…it was necessary to S-L-O-W-L-Y nudge the tuning thumbwheel until the signal suddenly jumped, then fine tuning was more of a matter of applying pressure to that thumbwheel rather than actually turning it noticeably.
Another enhancement is the addition of a gain control thumbwheel which offers better flexibility. With it you can reduce the gain if you suffer overload from excessive signals. All it is is a plastic stand that holds the ferrite sender and allows a small or medium size radio to lean against it at a convenient angle. While it certainly cannot begin to compete with much more expensive antennas such as a Wellbrook, Quantum Loop or C.
A loop antenna, as the name implies consists of a loop or number of loops made of copper wire wound on a nonconductive frame. The frame is generally made by joining two pieces of wood together to form an X .
Inverted U antenna for meters An Inverter U for the top band Do you find it hard to get on top band because of the antenna? This is a simple wire antenna that may be just what you need. It installs easily, needs no elaborate ground system, yet performs very well. A small ingenuity solves two connundrums at once — getting the current high in the air, and lowering the current in a very simple ground system.
Common problems — antenna too large One way to meet the size problem is by wrapping a loop antenna around the house, tuned to resonance with a capacitor. But a resonant meter vertical is more than feet high. Shorter whips need to be tuned to resonance with coils, and these are lossy. Therefore, most of the power goes into heating the coil and the ground system. Loaded vertical antennas have a current maximum at the ground. Every ohm of ground resistance is critical, as the I-squared R loss in the ground is lost power.
In standard AM broadcast antennas, low ground resistance is accomplished by using a minimum of radials spaced at 3 degree intervals. For amateur work, this is again a formidable undertaking. A bit of ingenuity If a meter whip were made more than feet high, the point of maximum current would no longer be at the ground; its feed impedance would be greater than the quarter-wave 38 ohm value, and would be inductive, not capacitive.
A series capacitor would be needed to bring it to resonance.
400 Bad Request
There is also a wealth of technical information on active loop antennas on his pages. His amplifier kit is an excellent value and has worked out very well for me. I have followed the loop construction guidance on the site. In fact, mine measures at 1. It is mounted on a 2 M mast and sits on a TV rotator allowing remote control from inside the shack. Why a new antenna?
Option number two: Winding your own RF matching/isolation transformers for broadband loop antennas is super easy, especially if a binocular ferrite core is used. Wire is threaded through one hole and then back through the other hole of the binocular core to complete one turn of a transformer winding.
AM radio with spiral-wound coil and home-made tuning capacitor The radios described here are a regenerative design utilizing a single JFET and cheap audio amplifier integrated circuit. These radios therefore are designed to work well with no external antenna. Another design problem was the tuning capacitors. In the end I found a way to make them out of blank copper clad printed circuit board material.
It ended up more educational anyway, since you can see exactly what it is, compared to the small plastic ones that were common in transistor radios. NOTE 19 Mar The antenna coil is 40 turns of thin, plastic covered hookup wire in a spiral construction used in radios of old. The reasons why I chose that were: I was surprised at how well it worked.
There were many stations in Mainland China to be heard at night.
Sony STR-DB925 Operating Instructions Manual
FM Transmitters This simple mW transmitter broadcasts audio on With good dipole antenna transmission range up to 4km is possible. Frequency is selected by adjusting R1 potentiometer. Transmitter should be powered by regulated V power supply with at least mA current rating. I must really confess that I also favor this broadcast band, mainly because it is so easy to find signals on the workshop radio. Everyone has an FM radio, and it is fun to play with.
For normal triangles, one can hang it from a cup hook or other hook on the ceiling, and bring the wires down to a horizontal stick, pvc, fishing pole, etc. The feedpoint is in .
The new design allows for a simply-wound ferrite loopstick antenna with a single coil winding, connecting to the radio’s circuit board on just two soldered pads. No more complicated coil with a secondary local oscillator winding or multiple coil taps. The radio’s chip tunes the single coil inductance for longwave through the top of the mediumwave band.
Replacing the ferrite antenna with something else is now easily possible. The common mod to these radios has been to remove the internal ferrite loopstick and replace it with a longer one, often mounted outside the radio on top. This new ferrite loop is then tuned by the circuitry of the radio just as the old loop was. The longer or beefier ferrite gives the radio much greater sensitivity. What about an air core loop?
Early on in reviewing the Si x chip’s documentation, I noticed the manufacturer showed an option of using an external, air core loop antenna as a substitution for the internal ferrite loop. Their suggestion was for a loop of minimal turns connected to the circuit board’s antenna terminals through a 1: It was apparent that using a full inductance loop was also possible.