rf antenna

437 links - and 1 categories

40m loaded dipole - This is an short dipole for 7 MHz. Total length of this dipole is just 10 meters, 33 feet. Missing lenght is balanced by a coil made of 49 turns of a 40mm diameter pvc pipe. The use of a choke balun is recommended, as always, to adapt the unbalanced coax cable to the balanced antenna, and to prevent RF feed back along the coax shield.
[ Hits: 194 | Votes: 4 | Rating: 8.75 ]

A very efficient half size 40 meter Vertical Antenna - A vertical antenna project for the 7MHz made with some spare parts. Based on a broken 20 foot fishing pole, it is based on a good ground system made with radials and a capacitive hat done to increase the global radiation resistance of the antenna. A custom loading coil is also included in this project to perfectly tune the antenna to the CW portion of the 40 meters band.
[ Hits: 736 | Votes: 4 | Rating: 8.5 ]

80m Shortened Dipole Antenna - This antenna just requires about 24m of free space instead of 41m that a normal half wave 80m antenna needs to hang up. The so called loaded dipole uses a coil in every dipole arm to electrically lengthen the mechanical too short dipole arms. Every coil has an inductivity of 120 microHenry.
[ Hits: 154 | Votes: 0 | Rating: 0 ]

Baluns and common mode chokes - Voltage baluns versus Current baluns. When to use them, differences, and typical usage in feeding antennas, or in resolving radio frequency interferences.
[ Hits: 402 | Votes: 1 | Rating: 10 ]
Build your own HF balun - A balun is a MUST for dipoles or similar antennas when they are feed with coaxial cable. From the RF point of view, the shield can be modeled as two conductors, the internal shield (the real shield, this is, ground) and the external shield, who is really far to be ground. In this way, your dipole has 3 arms, the two from the dipole and the coaxial cable shield (external face)
[ Hits: 248 | Votes: 1 | Rating: 10 ]

A Reversible Beverage at ZL3IX - How do two-wire reversible direction Beverages work, an excellent document that explains fundamentals of beverage antennas. This article details the design and performance of a reversible beverage antenna. Leveraging orthogonality between common mode and differential mode currents on a 2-wire line, this antenna facilitates independent reception from both ends. While common mode signals arrive and are summed on a transformer's secondary for common mode reception, differential mode signals induce anti-phase currents, providing individual reception. Various measurements explore impedance, transmission loss, and F/B ratio, highlighting the antenna's effectiveness and areas for improvement. Notably, increasing the antenna's height significantly improved performance.
[ Hits: 520 | Votes: 0 | Rating: 0 ]
The Single Wire Beverage Antenna - This simple beverage ntenna is easy to make, easy to setup, and it offers great RX performance.
[ Hits: 448 | Votes: 5 | Rating: 7.4 ]

Modeling an 80/40/20M Fan Dipole for DX - An interesting presentation of a real multiband Fan Dipole antenna, optimized for better DX operation performances, considering the terrain, position, DX destination path and other influencing factors
[ Hits: 540 | Votes: 2 | Rating: 5.5 ]

High Performance common-mode chokes - May 2015 Radcom Article on common-mode chokes that can be used for control cables, phone lines, but mostly on typical HF antenna systems. This article explain what common mode chokes does, why you meay need one, properties common mode chokes should have, how to build and measure performances.
[ Hits: 687 | Votes: 1 | Rating: 10 ]

History of the Hexbeam Antennas - The original HEXBEAM was developed by Mike Traffic, N1HXA, in the early nineties. It is true that an M over W configured yagi antenna that resembled a butterfly was earlier tried successfully. But the advanced electrical design, the characteristic nesting concept and central terminal post that enable the multi band functionality along with the basic hardware design were all developed by Mike Traffie.
[ Hits: 130 | Votes: 2 | Rating: 7.5 ]

Portable NVIS Loop for 80m to 40m - A portable (15.5 foot diameter) NVIS loop for 3.5 to 7.3 MHz. Performs well at high and low takeoff angles, and has smaller footprint than most NVIS antennas.
[ Hits: 366 | Votes: 0 | Rating: 0 ]

The Off-Center-Fed Dipole Antenna - The OCFD Off-Center-Fed Dipole Antenna is an excellent multiband antenna that is relatively simple to construct, yet gets quite decent performance.
[ Hits: 328 | Votes: 2 | Rating: 9 ]

160 Meters 4 Square Receive Antenna - A four square array receiving antena for the top band, performance is extremely directional and space requirements are really hard to fulfill.
[ Hits: 181 | Votes: 1 | Rating: 10 ]

Understanding Antenna Polarization - What is antenna polarization, and why does it matter. Horizontal versus Vertical versus Circular polarization. Undestanding how antennas perform better with different polarizations.
[ Hits: 169 | Votes: 1 | Rating: 2 ]

Tuning Antenna Traps - The problem with making your own trapped HF antennas is usually getting the coaxial traps tuned to frequency. This article explains a method using a RF signal generator at +10dBm output into the coaxial trap.
[ Hits: 276 | Votes: 2 | Rating: 6.5 ]

Modifications to the Diamond V2000 and similar antennas - This kind of antenna has grown in popularity over the last years because it gives you a decent performance and triband capabilities. But its 50 MHz design is far from optimal. Here you can learn how to improve its 50 MHz performance in a very easy way.
[ Hits: 631 | Votes: 2 | Rating: 9.5 ]

Ham Goodies - Amateur Radio goodies for not only the Shack, but also a range of outdoor/portable kit. Ferrite toroids, RTL SDR, Un-uns and Baluns for antennas and RF Filters. Based in the UK.
[ Hits: 145 | Votes: 0 | Rating: 0 ]

Hamtech - HAM-made engineering products supplies and produces coaxial relays, antenna switches, sequencers, roller inductors, variable capacitors, low noise preamplifiers, RF power rotary switches and coil bodies.
[ Hits: 192 | Votes: 0 | Rating: 0 ]

Wuxi Venus Information Technology - Wuxi Venus Information Technology is an amateur radio devices dealer in China, source for high end, high performance RF products,Control products,APRS products and Commercial products. It provides a variety of solutions to the antennas systems, APRS,electronics kits and electronics components
[ Hits: 178 | Votes: 0 | Rating: 0 ]

How to Ground an Antenna: aerial earthing - The antenna ground or earth system can be key to its operation whilst also being a key safety feature. This article is about grounding systems for antennas, covering different aspects of grounds made for antenna safety, or expressly for lightning or just to improve antenna performance, being ground an antenna component.
[ Hits: 232 | Votes: 1 | Rating: 4 ]