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I have a transceiver operating at 150MHz using a 1/4 wave vertical whip and horizontal ground plane at 90 degrees.

My end user doesn't like the antenna sticking up in the air (trip hazard) so I'm looking at a lower profile solution.

Is there any technical reason why something like this dipole couldn't be scaled up to suit 150MHz?

I have run some rudimentary tests with lengths of wires and a simple dipole seems to work but I'm not sure if a pcb trace would perform as well as a wire.

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    $\begingroup$ What is the orientation of the antenna you are trying to receive the signal with? Changing the orientation changes the orientation of the propagated signal. If the receiving antenna isn't at a similar orientation, my experience and understanding is that it will significantly reduce the quality of the received signal. $\endgroup$
    – David Hoelzer
    Commented Aug 7, 2022 at 12:05
  • $\begingroup$ It’s been a while since I done dipole calculations but if my calculations are not far off each element will be around 47cm making the overall length just shy of 1mtr or 97cm. This may actually be longer than the 1/4 wave your using. $\endgroup$
    – Dan K
    Commented Aug 11, 2022 at 16:27
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    $\begingroup$ Also keep in mind directionality. That's one advantage of 1/4 wave+ground plane, it's omni-directional (very helpful for mobile.) A horizontal dipole is not. $\endgroup$
    – Duston
    Commented Aug 16, 2022 at 13:48
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    $\begingroup$ where is this antenna placed such that it is a trip hazard? If it cannot be moved, this information will help us suggest an appropriate antenna geometry. $\endgroup$
    – webmarc
    Commented Mar 30, 2023 at 12:51

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The question is, what is your system's impedance? Because with your current configuration, your feed point impedance is likely 37 Ohms, and a dipole may be 73 Ohms, or higher, or lower depending on nearby objects around the antenna that either load or reflect; so depending on what your transmitter's output impedance is, if it is a poor match for your antenna, you can severely limit your power output, and if you have a poor impedance match, you will want to limit your transmit time so you don't damage your finals.

Ideally you have a VSWR meter, so you can first determine resonance of your antenna by plotting your VSWR over a range of frequencies, and if your lowest VSWR is at a frequency lower than your desired frequency, cut equal amounts off each element, if the best VSWR is above your desired frequency, add more equally to each element. Once you've gotten your resonant frequency to be where you want it, adjust the angle between the antenna elements for lowest VSWR at your desired frequency.

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The product you are looking at is a center-fed half-wavelength dipole. Note the length in the spec: 166 mm is right around a half-wavelength at 915 MHz.

Yes it will be lower profile and should work fine from an RF performance perspective, but it will be 2 m wide. You will also need a stiffer material. Is that acceptable?

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