[TenTec] Value of RX Only Antennas

[Bob McGraw - K4TAX]

There is also the Front to Back ratio that is often overlooked in favor of 
forward gain numbers.  Increased F/B ratio will reduce noise and QRM, even 
if the antenna has a lower gain than one touting higher gain.

All of my VHF & UHF antennas and associated arrays are designed for optimum 
front to back ratio with good side lobe suppression in favor of forward gain 
performance. Sacrificing 2 or 3 dB forward gain for increased 10 dB F/B 
ratio is certainly desired.    I also look carefully at E plane and H plane 
patterns as well.  This should be no different for HF antennas although they 
are physically larger.

73
Bob, K4TAX




----- Original Message ----- 
From: "Rick - DJ0IP / NJ0IP" <Rick at DJ0IP.de>
To: <k9yc at arrl.net>; "'Discussion of Ten-Tec Equipment'" 
<tentec at contesting.com>
Sent: Tuesday, October 01, 2013 2:29 PM
Subject: Re: [TenTec] Value of RX Only Antennas


> Jim,
>
> You are correct on the forward gain measurements but there is yet another
> aspect to it.
> But that's only half of the story.
> A multi-element yagi will have a lower angle of radiation than a simple
> dipole at the same height.
> This lower angle of radiation can result in significantly stronger signals
> at certain times of the day; much more than the 3 to 5dB the beam brings 
> in
> near-field measurements.  Sometimes it's a couple of S-units.
>
> In addition, the reduction of noise off of the back and sides often 
> results
> in a better signal to noise ratio; of course not if your beam is pointing 
> in
> the direction of the noise (hi).
>
> 73
> Rick, Dj0IP
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Jim Brown
> Sent: Tuesday, October 01, 2013 8:49 PM
> To: tentec at contesting.com
> Subject: Re: [TenTec] Value of RX Only Antennas
>
> On 10/1/2013 7:51 AM, Richards wrote:
>> These receive only antennas are nice to have, but I figure it is
>> better to improve one's transmit antennas if possible - especially if
>> one can can replace them with antennas with more gain.
>
> RX-only antennas are most useful on bands where it is impractical or
> expensive to get directivity from your TX antenna  -- 160, 80, 60, 40, and
> 30.
>
> Another VERY important point. Contrary to manufacturers' claims,  it is 
> VERY
> difficult to get much more than about 5 dB gain over a dipole with a
> collection of aluminum on a boom. That was the clear result of extensive
> measurements by N0AX and K7LXC of a dozen or so of a broad selection of
> tri-banders.  An M-squared C3 was the best of the small ones, with an
> average gain of 3.4 dB across the three bands. A Mosley
> TA33 was only 1.6 dB (loss in the traps made the difference).  An 
> M-squared
> C-31XR (31 ft boom) was the best of the big ones with 5.3 dB over a 
> dipole,
> a Cushcraft X9 was 5dB, a Bencher Skyhawk was 4.4 dB, the rest were less
> than 4 dB, and several big Mosley antennas had negative gain!
>
> 73, Jim K9YC
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