Receive Antenna for Small Space

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by NA4DX, Feb 15, 2020 at 12:29 AM.

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  1. NA4DX

    NA4DX XML Subscriber QRZ Page

    My current operating conditions limit my ability to install a beverage or long wire of any significant length. My lot size is less than 1/4 acre (about 120' x 75') and no trees. I do have some good attic space and have tried a 20m Moxon, an endfed dipole (10-40m) and a 10-40m Carolina Windom. My main operating antenna is a 43' ground-mounted vertical (6m-160m) with 16 buried radials (don't have space to bury any more). The vertical is a very good transmitting antenna but I need to do better on reception. There's too many stations that I either cannot hear well enough to complete a QSO or do not hear at all. I have several HF rigs (Flex 5000a, Yaesu FTdx3000, Kenwood TS-2000 and Kenwood TS-850S). I love the Flex and all its operating amenities, including the ability to connect a receive only antenna.

    I am looking for suggestions for the best receiving antenna (cost effective) that provides low noise and is broadbanded. I have an MFJ-998 full legal limit autotuner so matching this antenna to my radio is not an issue. What are your experiences with a high sensitivity, low-noise receiving antenna that would work for my situation? Thanks in advance, Larry, NA4DX
     
  2. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    Low noise and broadbanded are two mutually exclusive factors. Now if you really want low noise, it's hard to beat a multiturn tuned loop....very small and selective.
     
    N0TZU and NH7RO like this.
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    If you can use a separate RX antenna and NEVER transmit into it, a small loop with a broadband preamplifier (MFJ and lots of people offer these) is an excellent addition.

    Be aware that these are directional, so it's way better to install one on a rotator (a small, cheap rotator is fine, these things take almost no torque to turn) so you can use it to not only peak desired signals but also null undesired signals.

    Using a small loop (STL) to also transmit is much more challenging and unless you get into the big bux range it's hard to build or buy one that will handle much power.

    If with your vertical you believe you're getting out better than you're receiving (very possible) the problem is likely local noise. Even hams out in the country can experience this, if the noise is generated in their own house! And it often is.
     
    WB5YUZ likes this.
  4. KE0EYJ

    KE0EYJ XML Subscriber QRZ Page

    Magnetic loops are easy and cheap to build -- especially if they are just receiving antennas.
     
    KK4NSF likes this.
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    They are...but these can be -40 dB gain antennas, so can need a very good preamp to really work. And if using a preamp, it needs to be a really good one: Not "low noise," that doesn't matter. Needs to be "large dynamic range" to prevent overload or damage from nearby transmitters, including your own.:p
     
  6. KE0EYJ

    KE0EYJ XML Subscriber QRZ Page

    Work well here, but I'm using a cap (not wide-banded). Haven't needed any preamp past what's in my radio. My problem has been rotation. I finally have a radio with a RX input, but haven't had time to dicker with a dedicated RX loop on 40m. I have experimented with them, though.

    When Costa Rica was booming into Seoul a few years ago, I had my loop on it. Was pretty amazing how clear it was. This was in the small garden behind my office building in the center of the city. Lots of QRM here, actually. The loop did quite well. I had somewhere between 5 and 7kc bandwidth on this loop, if memory serves. Made quite a difference on 40m, but needed a lot of tuning.
     
    KK4NSF likes this.
  7. NH7RO

    NH7RO Ham Member QRZ Page

    LOG; kk5jy.net for details
     
  8. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    K3LR Tim Duffy did a talk about this at Hamcation last week.
    These are very good products to use in small places.

    Screenshot_20200212-093052_Chrome.jpg
     
  9. NA4DX

    NA4DX XML Subscriber QRZ Page

    As I stated my main rig is a Flex 5000a which allows for a dedicated receiving antenna. Has anyone had any experience with a Broadband Butterfly Terminated Dipole such as is described in the following youtube video?

    Is there any other wire type antenna that can be arrayed in an attic or along a roofline of a house that would serve as a good receiving antenna?
     
  10. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    Also in some situations small receiving Loops are highly effective for reducing the noise in certain directions
     
    N0TZU likes this.

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