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Base Antenna
- Thread starter Rabbid Possum
- Start date
Hey Greg T, been looking at Siro 2008 and maybe getting one as a replacement for my antron 99 , would I notice any difference and is it easy to put together,etc?? Just wondering..........
They are extremely easy to assemble because they use couplers between the sections. I also put a layer of electrical tape over the couplers, and then used heat shrink tube on top of that to make sure of a good seal. Depending on your location and elevation I believe you're going to find a major increase in your ears.
Thank you, I see on ebay that they are going for $199+free 4 day shipping,might have to pick me up one and put it in storage until the Spring when I can climb on the roof safely to install!!
Don't remember where I got mine. I do believe it was 179 shipped. I put together the Hub and the radiator
first and got it up on the tower, and then climbed up there and screwed the ground radials in afterwards. Much easier than trying to get the full size antenna on the roof
Per Tom Rouch, W8JI
This is the link to the 5/8th wave article we were all discussing.
As I recall, the disputed statements in the article were:
1.) Gain of a 5/8th wave over a quarter waves is not 4dB.
Without an infinite flat ground plane at antenna base height, like a sheet, a 5/8th wave has gain loss at low angles.
Assuming good matching system designs, gain with a perfect flat infinite sheet at base height is about 1 dB over a half wave (or 1/4 wave with down sloped radials, or something below 2.8dB over a 1/4 wave in the same ground plane situation.
Without that infinite sheet it has loss at low angles. This is why we no longer see them in professional antenna at VHF and lower, and why they disappeared from new AM BC service around the 1930's.
The ground plane has to extend out until the image is formed, that is a geometry problem caused by the radiation angles.
2.) The matching coil makes it behave as a 3/4 wave electrically.
The matching coil does not make it behave as a 3/4 wave. The series coil just corrects feed point reactance.
I think we should avoid thinking compact loading coils, small radius spirals, or lumped inductors as "adding antenna length". The antenna length, generally, is just the spatial linear length of the antenna. It is the spatial in-line ampere feet for simple small antennas.
The thought packing more wire length into a compact linear space makes a larger antenna is the root of many hoax or ill conceived antennas.
The possible gain of a 5/8th only occurs because Fresnel region reflections from an infinite flat ground plane forms an imaginary image antenna that appears exactly in phase with the real antenna. We have, in effect, a vertical extended double Zepp. The article gets that right, up at the very start, but neglects the important fact this occurs from the image and so the antenna needs a large flat infinite ground plane, at least a wavelength or more out radially to be really clean pattern. There has to be an image formed.
https://www.electronics-notes.com/a...antennas/five-eighths-wavelength-vertical.php
This is the link to the 5/8th wave article we were all discussing.
As I recall, the disputed statements in the article were:
1.) Gain of a 5/8th wave over a quarter waves is not 4dB.
Without an infinite flat ground plane at antenna base height, like a sheet, a 5/8th wave has gain loss at low angles.
Assuming good matching system designs, gain with a perfect flat infinite sheet at base height is about 1 dB over a half wave (or 1/4 wave with down sloped radials, or something below 2.8dB over a 1/4 wave in the same ground plane situation.
Without that infinite sheet it has loss at low angles. This is why we no longer see them in professional antenna at VHF and lower, and why they disappeared from new AM BC service around the 1930's.
The ground plane has to extend out until the image is formed, that is a geometry problem caused by the radiation angles.
2.) The matching coil makes it behave as a 3/4 wave electrically.
The matching coil does not make it behave as a 3/4 wave. The series coil just corrects feed point reactance.
I think we should avoid thinking compact loading coils, small radius spirals, or lumped inductors as "adding antenna length". The antenna length, generally, is just the spatial linear length of the antenna. It is the spatial in-line ampere feet for simple small antennas.
The thought packing more wire length into a compact linear space makes a larger antenna is the root of many hoax or ill conceived antennas.
The possible gain of a 5/8th only occurs because Fresnel region reflections from an infinite flat ground plane forms an imaginary image antenna that appears exactly in phase with the real antenna. We have, in effect, a vertical extended double Zepp. The article gets that right, up at the very start, but neglects the important fact this occurs from the image and so the antenna needs a large flat infinite ground plane, at least a wavelength or more out radially to be really clean pattern. There has to be an image formed.
https://www.electronics-notes.com/a...antennas/five-eighths-wavelength-vertical.php
This is absolutely true. When someone gives numbers of one vertical antenna over another, it is almost always with both of them over a flat, perfectly conducting, infinite plane, which doesn't actually exist in this world... In the real world, you see far less of a difference than even this.
Yes and no. The loading coil's purpose is not to shorten the antenna, but to change the phase of that part of the antenna, essentially bypassing or removing some of the out of phase currents, which keeps the pattern from going way up. It is one of the three ways to make a collinear antenna design. Personally, I think they would be better off using a 1/2 wavelength element and a coil above the 1/4 wavelength element. In the end, while I haven't modeled it, I think this design is more useful for conveniently matching the antenna and raising the antennas peak current point more than increasing gain from the collinear effect that is also happening, but as usual, the marketing department seems to be blowing said collinear effect out of proportion...
I have modeled antennas similar to this in the past, and I do intend to model this antenna as well, I just don't have the time at the moment.
The DB
As for which antenna is better, it's like girlfriends, the current one is always the best.
In most, if not all antenna setups it has much more to do with the installation than the particular antenna itself.
In most, if not all antenna setups it has much more to do with the installation than the particular antenna itself.
AE,
The Sirio Store (in California) has them for $145.
https://www.sirio.store/index.php?main_page=product_info&cPath=2_18&products_id=21
I have a Colossal 10K attached to a 35' ROHN Galvanized Telescopic Mast and it has been a great antenna for the past two years. Adjusting the external "sleeve" to get a good SWR is easy.
DXman
Yes, that's 3100 degrees F. Nine yrs of hard work.
Anything that is horizontal will be the best for you for good dxing. Forget the vertical GP's, a 3 element Yagi will work good on the 40' mast or even a 2 element V quad can get the job done.
Even a small Moxon can work dx very well also.
Even a small Moxon can work dx very well also.
Still learning antennas, but a yagi is a beam correct? Wouldn't that require a rotator?