Table of Contents
Do you need to ground J-pole antenna?
J-Pole antennas are half wave antennas by design. But instead of an RF ground, the antenna should have an electrical ground to protect it in case of a lightning strike. An electrical ground doesn’t enhance the RF radiation of the antenna, but it is an important safety feature on any installation.
Are J-Pole antennas directional?
The J-pole antenna, more properly known as the J antenna, is a vertical omnidirectional transmitting antenna used in the shortwave frequency bands.
How does a Slim Jim antenna work?
SLIM JIM ANTENNA PROJECT. The Slim Jim is a vertically polarized omnidirectional end-fed antenna having considerable “gain” and this is concentrated almost parallel to ground toward the horizon rather than skyward making it more efficient than a ground plane type antenna by about 50 percent better.
What is a Zepp antenna?
The MFJ-1748 End Fed Zepp is an end-fed wire antenna that, when properly erected and fed with balanced feedline through an antenna tuner, will be usable on all amateur bands from 80 to 10 Meters. This antenna will handle 1500 watts of RF power (with a suitable antenna tuner). Its total length is approximately 135 feet.
What is 300 ohm wire?
300 ohm twin lead is widely used to connect FM radios to their antennas, and was previously used to connect television antennas to televisions until it was replaced by coaxial cable.
How do you ground a Jpole?
hammer the top of the rod with a 5 pound hammer or small sledge hammer. As the rod is driven down, you may need to descend the ladder for the best angle to drive it. Once the rod is within a few inches of the ground, you can stop.
How does a folded dipole antenna work?
Folded dipole antenna basics The folded dipole antenna consists of a basic dipole, but with an added conductor connecting the two ends together. This makes a ‘loop’ of wire that is a short circuit to DC. As the ends appear to be folded back, the antenna is called a folded dipole antenna.
What is a Yagi type antenna?
A Yagi–Uda antenna or simply Yagi antenna, is a directional antenna consisting of two or more parallel resonant antenna elements in an end-fire array; these elements are most often metal rods acting as half-wave dipoles.
How good is a Slim Jim antenna?
The Slim Jim is probably one of the cheapest and easiest antennas to make, and it’s a very handy one too. You can typically make one of these for under £10, they roll up easily for storage and travel, and are great for use at home, or when travelling, for accessing local repeaters.
Is AJ pole a good antenna?
The myth is that j-poles have lots of gain and are better than anything else. A j-pole is just a 1/2 wave end fed antenna fed with a 1/4 wave transmission line matching section. If constructed and tuned properly, they only have as much gain (0 dBd) as a dipole.
What is a doublet antenna?
The doublet antenna is a form of dipole that uses a balanced feeder, often open wire feeder and an antenna tuning unit. As open wire feeder is able to operate with levels of standing waves and effectively becomes part of the antenna, it is able to operate over a wide band of frequencies.
Who is W8JI?
Tom Rauch, W8JI, is one of the most renowned antenna authorities of our times. He has an outstanding web site where he shares his knowledge with all of us who are willing to take the time and read it, AND he was the chief architect of the portfolio of Balun products sold by DX-Engineering in the states.
How long is a Slim Jim antenna?
Amateur Radio 2 Meter Slim Jim J-Pole Antenna The Slim Jim Antenna is an end-fed folded dipole antenna that has a gain of 6 dbi and a nice low RF take off angle.Product information. Package Dimensions 39.37 x 39.37 x 19.69 inches ASIN B07RBSY66H Date First Available April 30, 2019.
Can you use coax cable for antenna?
There are three types of cable in general use for FM antennas. One is the flat 300-ohm twin- lead cable that has been in use for decades. The second and more popular type is RG59/U 75- ohm coaxial cable. The typical line loss of RG59/U is about 3dB per 100ft at 100MHz.
Is coax better than ladder?
The advantage of ladder line over coaxial cable is its relative lack of loss. As you increase in frequency, say on the HF band (10m) or at VHF, ladder line will not experience as much power loss as coax. Ladder line actually has several disadvantages, which is why coax is more often used.
Are 2 ground rods required?
Suppose you drive the first ground rod for a system. If it has a ground resistance of 25 ohms or more, 250.56 of the 2005 NEC requires you to drive a second rod. Ground rods spaced less than two rod-lengths apart will interfere with each other because their effective resistance areas will overlap (Fig.
How far apart do ground rods need to be?
The NEC requires all driven rods to be a minimum eight feet in the earth and for multiple connected rods a minimum spacing of six feet between rods. The width of the rod has little effect on reducing impedance to earth, however, the depth of the rod and spacing for multiple rods have a significant effect.
What is the minimum depth for a ground rod?
The only legal ground rod must be installed a minimum of 8-foot in the ground.
Does a folded dipole need a balun?
Also in some antennas a balun is needed for impedance matching such as folded dipoles or off center fed dipoles. Some of the receiving antennas does not use balun . Usually these antennas are used in cheap receivers so having or not having balun does not make any serious difference.
