In article ,
John Doty wrote: On 14 Nov 2004 06:42:51 -0800, (RHF) wrote: So my 'focus' is on a "Low Noise' Inverted "L" Antenna that is 100 Feet long. Placing the Ferrite Rod at the "Top" of the Vertical Leg where the Antenna Wire Element transitions from Vertical to Horizontal. Rig the Antenna Wire Element with 33 Feet Up to the Ferrite Rod AM/MW Ferrite Coil and then have 67 Feet Out to the Far-End. Would this possibly work any better then having the Ferrite Rod and Coil at the Far-End ? and Why ? Generally, adding non-radiating reactance to an antenna decreases broadband efficiency, although it may increase efficiency over narrow bands. Good point. -- Telamon Ventura, California |
"Roy Lewallen" wrote
Once you have enough signal and noise to overcome your receiver's internal noise, there's no advantage of any further increase, since there's no improvement in the signal to noise ratio. __________________ Pardon the thread drift, but making the receive antenna directional can improve system SNR by reducing the total noise voltage delivered to the receiver input, as a ratio of the desired signal. RF |
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Thank You One and All for your Replies.
Well I have the two Inverted "L" Antennas and the proof would be in the Doing by de-rigging one and wrapping the Antenna Wire around a Ferrite Core; so that the Coil will be at the Top of Vertical Up-Leg. Then doing some Side-by-Side Testing of the two Antennas. NOTE: Taking a second look at the RF Systems "EMF" Antenna. The more I get the impression that it is susposed to be Rigged as a Vertical using the Coax Cable as a Counterpoise or may be as an Inverted "L" with the Coax Cable as the Vertical Up-Leg and the Antenna as the Horizontal Out-Arm. once again thank you very much one and all ~ RHF .. .. = = = Conan Ford wrote in message = = = .159... (RHF) wrote in om: FO&A, Here is my Question: Is there any sense in putting a Ferrite Rod at the Far-End of a Random Wire Antenna with the Wire from the End of the Wire Antenna Element 'wrapped' around it in a "Tuned Coil" to improve the AM/MW Band Reception ? * Any 'theory' behind why this Idea might Work ? * Does this Idea actually Work ? * Or is this Idea just so much Antenna 'hype' and Sales Marketing I am Asking these Questions is because of what I have read about the RF Systems "EMF" Electro-Magnetic-Field Passive Wire Antenna http://www.universal-radio.com/catalog/sw_ant/0743.html In "John Wagner's Shortwave Tips & Tricks" he writes: http://www.dxing.com/tips.htm "The EMF antenna has two 35mm film canister looking objects connected to it. The canister on the Far-End is actually an excellent "Tuned Ferrite Rod" designed for MW (Medium Wave) and really helps any receiver without a built in MW Antenna Rod. Canister two (in middle) is a Balun that helps SW reception very much." i want to know ~ RHF . . I have a 20 foot straight wire in my garage, that works better for MW DXing than the ferrite rods in any radio I have, due to the fact that it is much further from any noise sources in the house. I imagine the 16 foot wire being sold there would pick up some MW, but I doubt that adding the ferrite bar at the end helps one bit. |
Yes. My response was intentionally simplified. Making a directional
antenna is often not a viable option for an SWL, because they typically operate over a wide frequency range, and want to receive signals from many directions. This pretty much limits them to something like a rotatable log periodic antenna. Wire antennas can be made directional, but typically only in fixed or a small number of directions, and with directional patterns that change with frequency. Within the range of discussion, then, I don't believe it's realistic to attempt a directional antenna. The advertised antenna certainly doesn't produce any advantage in this regard. Roy Lewallen, W7EL Richard Fry wrote: "Roy Lewallen" wrote Once you have enough signal and noise to overcome your receiver's internal noise, there's no advantage of any further increase, since there's no improvement in the signal to noise ratio. __________________ Pardon the thread drift, but making the receive antenna directional can improve system SNR by reducing the total noise voltage delivered to the receiver input, as a ratio of the desired signal. RF |
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