Questions tagged [antenna]
Questions about the design, selection, building, testing, mounting, or properties of antennas. See also specific tags: [antenna-theory], [antenna-construction], [dipole], etc.
10
questions with no upvoted or accepted answers
4
votes
0answers
132 views
Dipole loading coil winding directions?
A single inductive loading coil in a vertical or a pair of loading coils in a dipole are commonly used to match a given total antenna length parameter to a given frequency wavelength (where the ratio ...
2
votes
0answers
97 views
What is happening in a gutter “antenna”?
can you explain me what is happening with RF in a iron gutter?
I've tried to simulate with nec2, but I'm just a beginner and doesn't really know all the parameters to come close to reality. This is ...
1
vote
1answer
15 views
How to calculate of shielded loop antenna correction factor without extra antenna measurements
A lot of article about 60 cm shielded loop antennas and how to measure antenna factor using antennas with already known antenna factor.
But for example if I have one shielded loop antenna (...
1
vote
1answer
50 views
The HPBW of a helical antenna
can someone tell me what are the formulas of HPBW for a helical antenna?
I've searched a lot and I saw that there are two different formulas of HPBW for the helical antenna,
this one,
$$ \mathbf{(HPBW)...
1
vote
0answers
27 views
How to cut phasing/transformer coax in a right way?
I'm building RHCP crossed dipole for 137 MHz satellites reception (I'm using 137.5 as a central frequency). My calcs are:
frequency is 137.5 MHz
λ is 2.18 m
one dipole leg length equals to the λ/4 so ...
1
vote
0answers
82 views
How do I Construct a Simple FM Antenna?
I recently bought a cheap stereo amplifier with built in FM receiver from Amazon at the first link below. Testing it out today I found the FM reception to be sub-par. All of my local stations that I ...
1
vote
0answers
251 views
What will be antenna impedance of a dipole antenna when it is kept lambda/2 away from the transmitter
I understand that half-wave dipole antenna, which is in far-field, impedance is around 73 ohms. If I keep same antenna in near-fied at distnace lambda/2 from the 1.25 lambda length tranmiter?
0
votes
0answers
13 views
Bidirectional motor control using MFJ-4116 with RCS-4
I have the RCS-4 with two MFJ-4116.
Prior to installing my motorized HF antenna system topside, I bench-tested the core of the assembly in my shack.
The MFJ-4116 near my transceiver was injected with ...
0
votes
0answers
48 views
Center-loaded vertical, high SWR at lower frequencies
I built a center-ish loaded coil-shortened vertical.
The lower radiator is 3 meters, then the coil, then 5M more radiator, like this (Early prototype with shorter radiators and no covers for the coil ...
-1
votes
1answer
123 views
How would I calculate aperture efficiency for an antenna?
How to calculate aperture efficiency for an antenna with the following parameters:
Big reflector diameter= 24 mm
Gain= 9.265 dbi
Frequency= 11.60 GHz
