ANALYTICAL TOOLS

As a company engaged in leading-edge antenna technology, Seavey Engineering develops many innovative antennas each year. We excel in solving antenna problems.

To start our design process, we ask you, our customer, for pertinent electrical, mechanical and environmental requirements. The form on Page 2 of this catalog may assist you in identifying your needs.

Using our very large product database consisting of more than 2,500 different antenna designs, we select a preferred approach in concert with you. This process can be done rapidly. We are proud of our fast reaction to your antenna inquiries.

Many customers desire short technical proposals, outline drawings and copies of test data of similar products. We deliver this information rapidly, often on the same day as the inquiry. AUTOCAD drawings, digitized radiation patterns and graphical information can be E-mailed to you.

In many instances, a new antenna design requires analysis to predict performance, verify the design approach and establish tolerance limits.

Seavey Engineering has many analytical tools and skilled antenna engineers and designers to accomplish this work.

Some tools are Reflector Modeling Geometric and Diffraction Models Paraboloidal, ellipsoidal, hyperboloidal Dual-reflector combinations Offset, rectangular-aperture or elliptical-aperture rim shapes Shaped and Dual-shaped antennas Gregorian and Cassegrain geometries Surface tolerance, feed misalignment, spar, plate, feed blockage simulations All feed variations; difference mode, off-axis and defocussed geometries Reflector interactions and coupling with wire antennas Reflector interactions and scattering from metal plates or solids Wire and Plate Antenna Finite-Element Modeling Any wire antenna Wires joined to plates Plates forming complex horn geometries Slots, corner reflectors, etc. formed from plates Any arrangement of dielectric materials

Array Design General planar array program Printed-circuit arrays Traveling-wave arrays Broadside slot arrays Any aperture distribution Excellent presentation graphics Microstrip Antennas Any patch element shape Impedance, patterns, losses, currents and nearfields Any dielectric material substrate or superstrate Mutual coupling Horn Antennas Pyramidal, conical, corrugated, rectangular horns Any mode excitation Dual-ridged design Quad-ridged, septum, dielectric-loaded and other complex designs Far- and Near-field analysis Phase center determination Any polarization component

Following an analysis of the proposed antenna, experimental model validation may be used to confirm some results. In many cases, such as wire-plate finite-element modeling, this has proven to be unnecessary due to the analytical power of modern computers.

In other cases with very complex geometry and many variables, an experimental model can be more cost- and time-effective. At the end of the 20th century, complex antenna design still requires ingenuity, insight into fundamental electromagnetic behavior and a deep familiarity with the possibilities of the state of the current antenna art. It is unlikely that such complex antennas will be reduced to cookbook formulas in the near future.

After a design has been determined, prototypes or deliverable units are fabricated using our in-house model shop. This can be done rapidly, often in a few days for simpler designs. Our microwave technicians, many with decades of antenna experience, quickly test and report on the performance. Adjustments are then made to the manufacturing drawings if necessary and a final test report is delivered with a formal outline drawing.

We manufacture many antennas using a CAD/CAM technique in which Autocad design information directly drives very large 3-axis CNC milling machines with the final product’s measurements validated by a 3-axis CMM machine.This procedure is especially useful for complex antenna arrays. All of this contributes to fast turn-around of antenna projects, thus benefiting your project schedule.

Model 9373-800 - High-directivity PCS Base-station Antenna 835 - 896 MHz. Folded pillbox design. Provides 10° azimuth beamwidth and 46° elevation beamwidth. 8-ft aperture. 18 inches high, 55 inches deep. Conforms to a highly-suppressed azimuth sidelobe mask (-30 dB at 45°). The photo below shows the scale model of the antenna. This antenna design was chosen because it has a non-blocked aperture and a compact, folded shape. The usable bandwidth exceeds 51%, thus making it useful for a wide range of applications requiring asymmetrical beamwidths. Beamwidth asymmetry up to 10:1 is entirely possible.

Very high power trihedral corner reflector antenna for a portable EMC flightline test set. Although optimized in the 870 - 960 MHz band, it operates well over an octave bandwidth from 725 - 1480 MHz. It has been tested at 325 KW peak power with 3.25 KW average power. Dimensions are 21.25 inches wide, 15.25 inches high and 14 inches deep. The RF port is a 1 5/8 inch 50 ohm EIA coaxial flange and is pressurized to 15 psig. Gains range from 11.2 to 12.5 dBi with the beam peak tilted about 25° from the mounting surface. This antenna mounts to a portable tripod. This antenna was entirely designed using a finite-element modeling program.

For some Cable Television applications, microwave point-to-multipoint distribution of (MMDS) signals can be more economical than coaxial cable. Regulations permit this in the 2 GHz and the 30 GHz frequency bands. In the lower frequency band, low-cost Yagi-type antennas are in wide use. However, for 30 GHz, a small parabolic reflector and a feed system integrated with a receiver is necessary. For this design problem, Seavey Engineering created a simple die-castable feed and a low-cost molded plastic reflector. The project required one month for design and testing and one month to fabricate several demonstration units. A transmit antenna (8814-800) was also developed.

Model 9373-800 Cellular Base Station Folded Pillbox Antenna (Scale Model)

Model 8814-810 Low-cost 30 GHz MMDS Antenna