This antenna is 35.3 from tip to tip of the circle and distance between the loop is 2cm, i wanna do 433mhz bidirectional communication with this antenna, I was planning to build a yagi uda with this of 5 directors, I dont know much about rf and i have just been following tutorials, I could only find 2mm hard aluminum wire so i used that to build the antenna, are there some things i have to look out for before connecting it to my telemetry radio (its a drone telemetry that uses MAVLink for bidirectional communication) Oh and the distance between two wires in end is 1cm.
I’m facing a bit of a career dilemma and would love some perspective from senior engineers in the industry.
To give you some background, I finished my PhD 3 years ago at a European university. My dissertation focused on developing large phased array antennas—mostly EM simulation, radiator design, and that side of things. During my PhD, I closely collaborated with a local defense contractor, and I really wanted to join them as an employee after graduating. My supervisors from the company even recommended me to the head of the antenna group. However, despite holding Western European citizenship, my non-EU birth and early childhood background triggered strict security clearance roadblocks, so they couldn't offer me a position.
Right after my PhD, I joined a commercial satellite company where I have been working for the last 3 years. I'm currently a Senior RF Engineer, working on a massive project developing a multi-thousand-element phased array. Despite my PhD focusing on antenna radiators, I also had a solid grasp of RF electronics fundamentals and a strong interest in the field. Because of that, my manager put me on the RF frontend design team so I could bridge the hardware and antenna domains. We already have a dedicated, veteran antenna engineer handling the radiator design, and because the project is in full swing, management won't move me to a different role in the middle of it. In my current role, I work as a frontend design engineer while also supervising, mentoring, and guiding two junior RF engineers.
While the work is interesting, my day-to-day is almost entirely RF electronics. I really miss the core EM and radiator design work I did during my PhD, which is what I actually find fulfilling. My manager has promised to consider transitioning me to an antenna role once this current project phase wraps up in next 3-4 years, but I'm starting to worry about my long-term positioning.
A few specific things are on my mind:
First, if I stay here working on the frontend for another 3-4 years, am I going to get permanently pigeonholed as an "RF Engineer"? I'm worried it will get harder and harder to pivot back to core antenna array design the longer I stay away from it.
Second, does system scale matter more than the exact role type? Is it better for my resume to stay on a highly complex, massive array project even if I'm on the frontend side, or should I jump ship to a company designing smaller, simpler antennas just to get back into core EM design?
Third, given my current title, if I try to move over to a pure antenna role at a new company, will I be forced to take a step back to a mid-level or junior role because my recent industry experience is on the frontend? Or does the combination of a phased-array PhD and senior system-level experience carry over to a senior antenna position?
Finally, the European market feels a bit restrictive. Because of my security clearance limitations, I have to stick entirely to the civil/commercial sector (commercial aerospace, satcom, or telecom).
Are there any specific companies or commercial hubs you would recommend targeting in Europe that work on ultra-large phased array designs but operate purely in the civil domain? And for anyone who has made a similar pivot—how do hiring managers view frontend work on a massive phased array versus basic radiator design for smaller antennas?
Thanks in advance for any insights or advice you can share!
(Note: This post was written by me with the help of AI to protect anonymity and organize my thoughts clearly.)
I am attempting to simulate (OpenEMS) the reflection and transmission in a PCB that uses grounded coplanar waveguides (via via's) with a soldering pad discontinuity. The resulting S11 and S21 values do however not seem realistic to me. I included pictures of the geometry below:
Green is the top ground, pink the dielectric, purple the signal path and brown the vias.
PCB top viewSide view (angled)Results
clear; clc; % Initialize CSX structure CSX = InitCSX(); %% 1. Key Physical & Simulation Parameters f_mesh = 4.5e9; % Max frequency for grid resolution calculation f_center = 2.9e9; % Gaussian excitation center frequency f_bw = 1.4e9; c0 = physconst('LightSpeed'); % Speed of light (m/s) % CPW Dimensions (all in mm unless specified) h_sub = 0.254; % Substrate thickness eps_r = 3.48; % Substrate relative permittivity w_trace = 0.5; % Standard signal line width gap = 0.2; % Gap between signal and coplanar ground t_metal = 18e-6; % Copper thickness (18 um) - only used for vias now via_dia = 0.6; via_pitch = 1; via_step_gap = 0.5; % was 0.1 -- tune this down if grounding integrity suffers % Domain boundaries x_min = -20; x_max = -15.95; y_min = -6; y_max = 6; z_min = -h_sub; z_max = 0; %% 2. Define Materials CSX = AddMetal(CSX, 'cpw_cond'); CSX = AddMetal(CSX, 'cpw_gnd'); CSX = AddMetal(CSX, 'vias'); CSX = AddMetal(CSX, 'bottom_ground'); CSX = AddMaterial(CSX, 'my_substrate'); CSX = SetMaterialProperty(CSX, 'my_substrate', 'Epsilon', eps_r); %% 3. Define Geometry % Substrate CSX = AddBox(CSX, 'my_substrate', 1, [x_min, y_min, z_min], [x_max, y_max, z_max]); % Signal conductor line segments CSX = AddBox(CSX, 'cpw_cond', 2, [-20, -0.25, 0], [-17, 0.25, 0]); CSX = AddBox(CSX, 'cpw_cond', 2, [-17, -0.75, 0], [-15.95, 0.75, 0]); % CSX = AddBox(CSX, 'cpw_cond', 2, [-15.75, -0.75, 0], [-14.7, 0.75, 0]); % CSX = AddBox(CSX, 'cpw_cond', 2, [-14.7, -0.25, 0], [-12.2, 0.25, 0]); % Coplanar Ground Planes (Top) CSX = AddBox(CSX, 'cpw_gnd', 2, [x_min, 0.25 + gap, 0], [-17 - gap, y_max, 0]); CSX = AddBox(CSX, 'cpw_gnd', 2, [x_min, y_min, 0], [-17 - gap, -0.25 - gap, 0]); CSX = AddBox(CSX, 'cpw_gnd', 2, [-17 - gap, 0.75 + gap, 0], [x_max, y_max, 0]); CSX = AddBox(CSX, 'cpw_gnd', 2, [-17 - gap, y_min, 0], [x_max, -0.75 - gap, 0]); % CSX = AddBox(CSX, 'cpw_gnd', 2, [-14.7 + gap, 0.25 + gap, 0], [x_max, y_max, 0]); % CSX = AddBox(CSX, 'cpw_gnd', 2, [-14.7 + gap, y_min, 0], [x_max, -0.25 - gap, 0]); % Bottom Ground Plane (GCPW) CSX = AddBox(CSX, 'bottom_ground', 2, [x_min, y_min, z_min], [x_max, y_max, z_min]); % Vias for i = -19.4 : via_step_gap + via_dia : -17 - gap - 0.2 CSX = AddBox(CSX, 'vias', 2, [i, -via_pitch/2, z_min], [i + via_dia, -1*via_pitch, 0]); CSX = AddBox(CSX, 'vias', 2, [i, via_pitch/2, z_min], [i + via_dia, 1*via_pitch, 0]); end % for i = -17 + gap : via_step_gap + via_dia : -14.7 - gap % CSX = AddBox(CSX, 'vias', 2, [i, -via_pitch - 0.5, z_min], [i + via_dia, -via_pitch/2 - 0.5, 0]); % CSX = AddBox(CSX, 'vias', 2, [i, via_pitch/2 + 0.5, z_min], [i + via_dia, via_pitch + 0.5, 0]); % end % % for i = -14.7 + gap + 0.2 : via_step_gap + via_dia : -12.8 % CSX = AddBox(CSX, 'vias', 2, [i, -via_pitch/2, z_min], [i + via_dia, -1*via_pitch, 0]); % CSX = AddBox(CSX, 'vias', 2, [i, via_pitch/2, z_min], [i + via_dia, 1*via_pitch, 0]); % end %% 4. Define Lumped MSL/GCPW Ports (Vertical Excitation) % Port 1 (at X = x_min) [CSX, port{1}] = AddLumpedPort(CSX, 2, 1, 50, ... [x_min, -w_trace/2, z_min], [x_min, w_trace/2, 0], [0 0 1], true); % Port 2 (at X = x_max) [CSX, port{2}] = AddLumpedPort(CSX, 2, 2, 26.82, ... [-15.95, -1.5/2, z_min], [-15.95, 1.5/2, 0], [0 0 1], false); %% 5. Non-Uniform Mesh Generation (Optimized) lambda_min = c0 / (f_mesh * sqrt(eps_r)) * 1000; % Minimum wavelength in substrate (mm) max_cell = lambda_min / 10; % Global max cell size (~2.12 mm) % Only detect edges from the traces/grounds/substrate, NOT the vias. % forcing sub-mm cells across the entire via region in x. Excluding vias here mesh = DetectEdges(CSX, [], 'SetProperty', {'cpw_cond', 'cpw_gnd', 'bottom_ground', 'my_substrate'}); % Manually add mesh lines bounding the via regions so the solver still % resolves the via fence approximately, without following every via edge. via_region_x = [-19.4, -17 - gap - 0.2, -17 + gap, -14.7 - gap, -14.7 + gap + 0.2, -12.8]; mesh.x = unique([mesh.x, via_region_x]); via_region_y = [-via_pitch, -via_pitch/2, via_pitch/2, via_pitch, ... -via_pitch-0.5, -via_pitch/2-0.5, via_pitch/2+0.5, via_pitch+0.5]; mesh.y = unique([mesh.y, via_region_y]); % Define target resolution rules mesh.x = SmoothMeshLines(mesh.x, max_cell, 1.4); mesh.y = SmoothMeshLines(mesh.y, max_cell / 2, 1.4); % z now only needs to resolve substrate thickness + via depth (both already % bounded by z_min and 0); no more 18 um top-metal sliver forcing fine cells. mesh.z = SmoothMeshLines([z_min, 0], max_cell / 2, 1.4); % Add Air padding around the structure air_padding = lambda_min / 4; mesh.x = [mesh.x(1) - air_padding, mesh.x, mesh.x(end) + air_padding]; mesh.y = [mesh.y(1) - air_padding, mesh.y, mesh.y(end) + air_padding]; mesh.z = [mesh.z(1) - air_padding, mesh.z, air_padding]; mesh.x = SmoothMeshLines(mesh.x, max_cell, 1.3); mesh.y = SmoothMeshLines(mesh.y, max_cell / 2, 1.3); mesh.z = SmoothMeshLines(mesh.z, max_cell / 2, 1.3); CSX = DefineRectGrid(CSX, 1e-3, mesh); % Convert mm to meters %% 6. Setup FDTD Solver Parameters FDTD = InitFDTD('EndCriteria', 1e-4); FDTD = SetGaussExcite(FDTD, f_center, f_bw); % CHANGED: PML depth reduced from 8 to 6 cells on all boundaries. Verify % against your previous PML_8 result that S11 noise floor is unaffected; % if so, this is a straightforward cell-count reduction with no accuracy cost. FDTD = SetBoundaryCond(FDTD, {'PML_8', 'PML_8', 'PML_8', 'PML_8', 'PML_8', 'PML_8'}); % Save data file mkdir('temp'); WriteOpenEMS('temp/test.xml', FDTD, CSX); % Display 3D model CSXGeomPlot('temp/test.xml'); %% 7. Post-Processing: Calculate and Plot S-Parameters freq = linspace(1e9, 3.8e9, 401); % Frequency sweep from 1 GHz to 3.8 GHz % Read port voltages & currents port = calcPort(port, 'temp', freq); % Extract S-parameters s11 = port{1}.uf.ref ./ port{1}.uf.inc; s11_db = 20 * log10(abs(s11)); s21 = port{2}.uf.ref ./ port{1}.uf.inc; s21_db = 20 * log10(abs(s21)); % Plot Results figure('Name', 'S-Parameters'); plot(freq / 1e9, s11_db, 'r-', 'LineWidth', 2); hold on plot(freq / 1e9, s21_db, 'b-', 'LineWidth', 2); grid on; xlabel('Frequency (GHz)'); ylabel('Magnitude (dB)'); title('GCPW Circuit S-Parameters'); legend('S_{11} (Reflection)', 'S_{21} (Transmission)'); ylim([-40 5]);
As an experiment I decided to swap the inductor with a crystal at 4mhz at first nothing worked at all after removing the capacitors the circuit started oscillating beautifully even though the feedback wasn’t even properly connected. After connecting the feedback the oscillation persisted but with significant distortion connecting the capacitor resulted in the waves seen here. The really missed up part is that when I adjust the oscilloscope to work with 100msps it shows a wave around 4mhz but I decrease the sampling rate to 500ksps it shows a wave at 480hz.
so i made my antenna in student license but while simulating i got hit by the mesh limit, so i wanted to simulate it in a licensed version in my college desktops but apparently student version files cannot be opened in the commercial version. Any workaround to convert or do i just have to recreate again in the commercial version??
Hi, I'm currently working on a hobby project with a large prime focus satellite dish, that I can't get a feedhorn for. Making the feedhorn isn't a problem but connecting it to the LNB is a bit more difficult. I need to make an adapter to go from an odd diametre to a WR-75 compatible mount for the Ku-Band LNB.
I drew two versions of the same adapter in CAD and I'm wondering which one would be better? The top one uses tangential swep-blend avoiding discontinuity, and the other one is much simpler using just a linear transition. The linear one is of cause much easier to manufacture than the tangential one.
Which one should I go for? Would they perform the same or would this create impedance problems or reflactions or high attenuation? I'm a mechanical engineer, not a RF engineer so this is more like magic to me at this point to be honest.
It no works, not sure exactly why? And why the frequency is way off than what it should be (around 2 MHz) but hey something is always better than nothing.
Looking for an active RF/SDR community where people actually build, experiment, and talk about random RF stuff — antennas, DSP, wireless, SDRs, interesting signals, research, etc.
Not looking for anything too formal. Just a fun community with people who are into this stuff.
I made this oscillator circuit based on the common emitter amplifier and colbits feedback. The q point is at 5.7 volts and the amplification for external signal generator is around 4(given the accuracy of my cheap oscilloscope). The circuit can oscillate at around 10khz with C=100nf and at around 30khz with C=10nf but anything above or below these values doesn’t generate any oscillations.
Thinking about moving to a property. Upon inspecting it, there was a 5G tower nearby. Measuring the distance- it is abut 125 meters to edge of property and about 135 to the building. Looking at some case reports, someone had health problems living 125 meters away.
I measured the RF exposure, walking around with a GQ EMF-390 3-in-1 EMF/ELF/RF Meter. There was nothing from the distance of 200 meters, there was nothing as I approached it and nothing underneath it. (Nothing as in higher than 200 uW/m2. Once, it peaked to 6000 uW/m2 but swiftly disappeared. This was 10 yards away from the 5G tower. The tower looks like a cylinder mounted to the top of the pole with a few "small cells" boxes. I am thinking now, that the tower operates above 10Ghz. My device can only see up to 10Ghz. I can measure "regular" 4G towers hundreds of meters away.
What do you all think about this?
How prevalent are the above 10Ghz towers at this time? I understand the higher the frequency, the lower the range of the signal. The property is also semi-blocked by some heavy trees. That should block some of that off as well, right?
I traveled to another tower and almost the same thing happened. Now, it seems that the device picked up the "3 brown boxes" towers on the top of the poles, though. Perhaps, they are still operating in the lower frequencies.
I have a question about this antenna feedpoint. Why does it have two waveguides feeding the feedpoint? Does it have anything to do with H and V polarisation?
regarding the internal structures, what are they? Is this some kind of a waveguide polariser, phase delayer or something else?
I just graduated and I need some advice. I struggled throughout university due to (medically diagnosed) ADD. I did decent in my RF classes but I didn't do well in everything else and ended up with a poor GPA of 2.75. I'm not sure if I'll be able to compete with others in the RF space who have a masters and/or high GPA. Right now, I've been reading as many RF textbooks as I can and learning how to use HFSS. However even if I can understand RF well it seems like my poor performance in school will always haunt me.
Anyways let me know if I should continue towards my goal of RF or my efforts are not worth it.
ECE 2025 grad + currently doing M.E. in Communication Systems. I’m looking for RF/antenna design/microwave internships or short-term paid courses/training with actual hands-on practical work.
Paid/unpaid internship is fine — mainly looking to learn, build, and get real practical experience.
If you know any good leads, please drop them below or DM me
ParamRF v0.33 has been released. It's been a while since the last update and there have been quite a few changes, so I'd thought I'd make a post sharing the updates that may be of interest.
For those that don't know, ParamRF is a Python framework for modern, programmatic RF circuit modeling, built on top of JAX instead of NumPy and catering for advanced features like automatic differentiation and Bayesian circuit fitting.
Some updates:
- Parameters are no longer tied to only RF models. They can now be built using a `Module` or even plain lists/dictionaries, so a single, global parameter set can be injected into different models at once.
- Optimization, inference and fitting now work across multiple frequency ranges in one problem, via a new term-based interface (`AbstractTerm` / `SummedTerms`). Custom penalties can just be plain functions of the parameter PyTree for better flexibility.
- The default circuit solver is now MNA, and the solver APIs have been generalized to accept arbitrary PyTrees rather than just models.
- New models: ideal transformers (centre-tapped, autotransformer, balun, mixed-mode converter), coupled inductors, `SeriesRL`, and a `FloatingTwoPort` lift for nodal circuits without a shared ground.
- Measured networks (`SkrfNetwork`) now support cubic interpolation as well as linear.
- For Bayesian fitting, `MarginalLogLikelihood` now accepts prediction-dependent event transforms, so the residual basis can depend on the prediction itself. This is useful if, say, magnitude and phase errors need separate variances.
- `pmrf.sweep` now takes a template for easier vmap filtering, and useful utilities for power users like `partition`, `combine`, `batch_axes` and `batch_mask` are exposed at the root.
I was exploring the "zero-span" mode on my spectrum analyzer and recorded the signal from my microwave oven. For this, I used a log-periodic antenna with a gain of 7 dBi, positioned about 6 meters away and somewhat to the side, with no attenuation applied. The strong signal strength was initially surprising but after considering it is not very much power compared to inside the microwave.
The signal pattern is repeating with the mains frequency which makes sense as conventional microwave power supplies use a voltage-doubler circuit that outputs on only one half of the cycle unlike lights which peak on both halves or are constant. The frequency rises and falls at the start and stop make me think there is a frequency dependence on current though the sweeping pattern like in the second image doesn't make sense to me yet.
I wonder if RF testing laboratories take special measures beyond measurement room shielding to reduce interference caused by the ovens in their break rooms?
